Fun with eucraniines!

During my February/March 2015 visit to Argentina, I had the opportunity to travel to west-central provinces of San Juan and San Luis with Federico Ocampo for a weekend of insect collecting. Up to that point most of my collecting in Argentina had been limited to the northeastern provinces (Chaco, Corrientes, and Misiones), so I was excited for the chance to explore a radically different biome. West-central Argentina represents a transition zone from the flat, wet, treeless plains of the Humid Pampas in east-central Argentina (Buenos Aires, Santa Fe, and Córdoba Provinces) to the massive Andes Mountains running along the western edge of South America. This area is home to the Monte, a desert biome characterized by volcanic sediments, piedmont plains, large mountain blocks and dry salt lakes. Conditions in the Monte are generally more hospitable than in the neighboring Atacama and Patagonian Deserts lying north and south of the Monte, respectively. As a result, the flora and fauna in the Monte is relatively rich and characterized by a diversity of shrubs, grasses, and cacti.

Dunas de Encón

Encón Dunes, San Luis Province, Argentina

Of the several sites we visited in the area, the most remarkable was “Las Dunas de Encón” (the Encón Sand Dunes) in San Luis Province. Belonging to a larger system covering some 250,000 hectares—the largest in South America (and, thus, sometimes called the “Argentinian Sahara”)—the dunes are thought to have formed some 100–200K years ago as a result of dry conditions brought on by Quaternary glaciations. I find sand dune systems endlessly fascinating due to their unique and often endemic plants and animals and have visited many systems in North America (Bruneau, Coral PinkGlamisGreat, Medora, St. Anthony, and others), but this was the first sand dune system I’ve had the opportunity to see outside of the U.S. Federico, a scarab specialist, shares that fascination and has, in fact, described a number of species in the scarabaeine tribe Eucraniini—endemic to South America—that utilize these very sand dunes (Ocampo 2005, 2007, 2010). He was hoping one or more of them might be out and about; I was hoping to see anything, really.

Host for Lampetis spp.

Parkinsonia praecox? – adult host plant for Lampetis baeri and L. corinthia.

One of the first plants that caught my attention was a woody, fabaceous shrub that looked very much like what I would have previously called Cercidium, now Parkinsonia, and which after a bit of digging I conclude is likely Parkinsonia praecox. Woody, fabaceous shrubs in desert habitats are a sure bet to host jewel beetles, so I began paying special attention to each shrub as I wandered by. It wasn’t long before I saw a large, brilliant metallic green jewel beetle sitting on an outer branch of one of the shrubs—it was one of the most beautiful jewel beetles I have ever seen out in the field with my own eyes! I managed to catch it, and over the next few hours I collected not only several more of this species but also several individuals of an even larger, more somber-colored species. I was able to identify them as Lampetis baeri (Kerremans, 1910) and L. corinthia (Fairmaire, 1864), respectively, when I compared them to material in the collections at Fundacion Miguel Lillo, Instituto de Entomologia, Tucuman, Argentina [IFML]) during my visit there the following week (see photos below).

Lampetis baeri (Kerremans, 1910)

Lampetis baeri (Kerremans, 1910) [IFML]

Lampetis corinthia (Fairmaire, 1864)

Lampetis corinthia (Fairmaire, 1864) [IFML]

As a jewel beetle enthusiast, you would think that was the highlight of my day. In fact, the fun had only started. For a time after our arrival, Federico pointed out burrows likely made by eucraniine adults, but we didn’t see any evidence of activity at first. It wasn’t long, however, before we found the first adult—a fine Eucranium beleni Ocampo, 2010, the largest of the three species occurring at this site (about the size of our North American Deltochilum). One of the more obvious features of eucraniines is their enormously enlarged forelegs and pronotum to hold the musculature required to carry—that’s right, carry!—provisions to the larval burrow (in contrast with the more commonly seen habit among members of the subfamily of using the hind legs to push provisions to the burrow). This unusual morphology gives these beetles not only an amusing, shuffling gait but also a rather comical method for turning themselves upright (as seen in this video narrated by Federico). There are other dung beetles that pull, rather than push, larval provisions (e.g., Sisyphus spp., which stand on highly elongate hind legs and walk backwards while pulling the dungball), but eucraniines seem to be the only ones that actually lift provisions off the ground to carry them. In the case of E. beleni, this involves carrying pieces of dung with the forelegs held out in front of the head while walking forward on the middle and hind legs (Ocampo 2010). I didn’t get to see that behavior with E. beleni, but I did see it with one of another of the eucraniines we found that day (see below). In the E. beleni photo below, note the brushy middle and hind tarsi—an adaptation for walking on loose sand.

Eucranium belenae

Eucranium belenae Ocampo, 2010 walks on its middle/hind legs while holding its forelegs aloft.

Eucranium belenae burrow

Eucranium belenae burrow plugged with a piece of dung.

The second species in the group that we encountered was Anomiopsoides cavifrons (Burmeister, 1861). This species is much smaller than E. beleni (about the size of a large Onthophagus), and unlike E. beleni—and, in fact, most other dung beetles—the larvae of A. cavifrons develop on plant matter rather than dung. Both males and females provision the larval burrows with pieces of plant debris that they pick up with their front legs and carry back to the burrow while walking on their other four legs. This rather amusing video shows a male bringing a piece of debris back to his burrow, then exiting to find and retrieve another piece of debris to bring back to the burrow. The molar region of their mandibles is heavily sclerotized for masticating the plant fibers in preparation for the larvae. There are a couple of other species in the tribe that opportunistically include plant matter in their diet, but A. cavifons seems to be the only one known to utilize dry plant matter in desert habitats almost exclusively (Ocampo 2005). Anomiopsoides cavifrons was far more abundant in the dunes than E. beleni, and by early to mid-afternoon they were encountered with such regularity that I stopped even looking at them.

Anomiopsoides cavifrons male at burrow

Anomiopsoides cavifrons (Burmeister, 1861) male at burrow entrance.

We also were fortunate to see a few individuals of the third species known from these dunes, Anomiopsoides fedemariai Ocampo, 2007. This species is intermediate in size between the extremes represented by E. beleni and A. cavifrons and utilizes pellets of the plains viscacha (Lagostomus maximus), a species of rodent in the family Chinchillidae, for food (Ocampo 2007).

REFERENCE:

Ocampo, F. C. 2005. Revision of the southern South American endemic genus Anomiopsoides Blackwelder, 1944 (Coleoptera: Scarabaeidae: Scarabaeinae: Eucraniini) and description of its food relocation behavior. Journal of Natural History 39(27):2537–2557 [pdf via DigitalCommons].

Ocampo, F. C. 2007. The Argentinean dung beetle genus Anomiopsoides (Scarabaeidae: Scarabaeinae: Eucraniini): description of a new species, and new synonymies for A. heteroclytaRevista Sociedad Entomología Argentina 66(3–4):159–168 [pdf via SciELO Argentina].

Ocampo, F. C. 2010. A revision of the Argentinean endemic genus Eucranium Brullé (Coleoptera: Scarabaeidae: Scarabaeinae) with description of one new species and new synonymies. Journal of Insect Science 10:205, available online: insectscience.org/10.205 [pdf via DigitalCommons].

© Ted C. MacRae 2016

The best species name ever!

Entomoderes satanicus

Entomoderes satanicus | Ruta Nacional 20 @ km 367, San Luis Province, Argentina

This past February while traveling to see research plots in Argentina, I had the pleasure of accompanying colleague and scarab expert Federico Ocampo to San Juan Province in west-central Argentina to see some of the endemic scarabs that live in the sand dunes that dot the region. Along the way we made a quick stop at a sandy spot along Ruta Nacional 20 in San Luis Province to see what was out and about. Several interesting insects were seen, but one of the most impressive was this marvelously armoured darkling beetle (family Tenebrionidae) belonging to the genus Entomoderes—also endemic with nine species ranging from southern Bolivia to central Argentina (Flores & Roig-Juñent 1997).

Entomoderes satanicus

Stout spines and a heavily sclerotized body surely provide effective anti-predation defense…

The stout, backwards-directed lateral spines on the pronotum are as evil as any I’ve ever seen, perhaps being the the reason behind the most awesome species epithet I have ever encountered—satanicus! Actually, there was some question about whether it represented this species or another in the genus with an almost equally awesome name—draco! I wasn’t able to access the more recent, paywall-protected revision by Flores & Roig-Juñent (1997); however, a relatively recent prior work (Peña 1990) seems to confirm its identity as the former by the presence of distinct raised costae on each elytron between the lateral keel and sutural margin confirm.

Entomoderes satanicus

…but not from tiny enemies (note parasitic mite on the venter behind the right procoxa).

Surely the sharp, stout spines and heavily sclerotized, ridged body provide effective protection from vertebrate predators and perhaps also help to minimize loss of water, since all of the species are found strictly in arid habitats (Peña 1990). I did not collect the specimen, but many such heavily sclerotized darkling beetles can be difficult to nearly impossible to pin by normal means (I have actually used a hammer to help in the case of one species I collected in South Africa. Seriously!), and I’m sure this one would have been no different. For all its armoured protection, however, there still remain chinks—note the tiny, bright red, parasitic mite on the ventor behind the right procoxa in the last photo.

REFERENCE:

Flores, G. E. & S. Roig-Juñent. 1997. Systematic revision of the Neotropical genus Entomoderes Solier (Coleoptera: Tenebrionidae). Insect Systematics & Evolution 28(2):141–162 [abstract].

Peña, L. E. 1990. El género Entomoderes Solier (Coleoptera: Tenebrionidae). Boletin del Museo Nacional de Historia Natural Textos sobre patrimonio natural de Chile 37:253–259 [ISSUU].

© Ted C. MacRae 2015

Buprestidae type specimens at Fundación Miguel Lillo, Argentina

During my most recent visit to Argentina this past February and March, I had the chance to go behind the scenes and visit the entomology collection at Fundación Miguel Lillo, Instituto de Entomología, Tucumán. It’s always a treat to visit any entomology collection—public or private—at any location. When the collection has holdings of Buprestidae, so much the better. Much to my delight, however, this collection not only had holdings of Buprestidae (not surprisingly representing primarily Argentine species), but also a small collection of type specimens designated by Antonio Cobos Sanchez (1922–1998). Cobos was one of the 20th century’s most prolific students of Buprestidae, with publications in the family spanning the period from 1949–1990 (coincidentally, 1990 being the year of my very first buprestid publication!). I was graciously allowed to photograph these specimens, some of which present interesting nomenclatural situations that are worthy of comment. These are presented below with my notes.

Jose xx & Ted MacRae

Looking at the insect collection at Fundación Miguel Lillo, Argentina.


Sufamily POLYCESTINAE

Tribe TYNDARINI

Tylauchenia golbachi Cobos, 1993 (currently placed in Oocypetes)

Tylauchenia golbachi Cobos, 1993. The species was moved to the genus Ocypetes.

Lapsus calami or mislabeled type specimen? Cobos (1973) described Tylauchenia golbachi from Argentina (now placed in the genus Ocypetes), stating the type locality as “6 kms. N. de Belén, 1.240 m. alt., Catamarca, Argentina (Willink, Terán y Stange coll., con trampa de Malaise, 1-15-I-1970…)”. The specimen above bears the holotype label, but the locality label clearly shows that it was collected in Tucumán rather than Catamarca and that the collector’s name is Guanuco rather than the above stated names. Interestingly, in the same publication Cobos gives the allotype female collection data as “San Pedro de Colalao, Tucumán, Argentina (Coll. Guanuco, 9-III-1949)”. At first I thought this might actually be the allotype rather than the holotype; however, 1) the specimen clearly bears a holotype label, and 2) it is also clearly a male based on the dissected genitalia preserved on the label below the specimen. There are two possible explanations, both of which make it difficult to determine what is the true type locality: 1) the holotype and allotype specimens are correctly labeled, but Cobos simply transposed their label data in his publication describing the species, making Tucumán the true type locality, or 2) the holotype and allotype locality labels were switched at some point and the true type locality is Catamarca, as stated in the publication in which the species is described. This latter possibility is more serious, as in addition to the doubts it generates regarding the type locality it also raises concern about the integrity of the holotype specimen. The latter explanation, however, seems less likely, as it is more difficult to imagine a scenario where only the locality label but not the others was switched than to imagine a transposition of label data in the publication. Sadly, at this point, there seems no easy way to determine which of the two explanations is correct.

Subfamily CHRYSOCHROINAE

Tribe DICERCINI

Lampetis tucumana monrosi Cobos (nomen nudum?)

Lampetis tucumana “monrosi” Cobos (ms name?)

A manuscript name? Cobos never actually proposed a subspecies “monrosi” for Lampetis tucumana (Guérin-Méneville & Percheron, 1835) (the name on the separate box label is misspelled). He did use the name for two other buprestid taxa: Tetragonoschema monrosi Cobos, 1949—now regarded as a synonym of T. argentiniense (Obenberger, 1915), and Anthaxia monrosi Cobos, 1972—now placed in the genus Agrilaxia. The holotype label on the specimen clearly states “Lampetis tucumana monrosi” in Cobos’ handwriting, so one can only presume that Cobos had identified this specimen as representing a distinct subspecies but never followed through and actually described it.

Ectinogonia (Pseudolampetis) fasciata metallica Cobos, 1969

Psiloptera (Pseudolampetis) fasciata metallica Cobos, 1969. Pseudolampetis was later considered a subgenus of Ectinogonia but is now regarded as a full genus.

Oh, what a tangled web we weave! Cobos (1969) originally described this taxon as a subspecies of Psiloptera (Pseudolampetisfasciata Kerremans, 1919. Moore (1986) moved Pseudolampetis to a subgenus of Ectinogonia, which resulted in two taxa in the latter genus bearing the name “metallica“—Ectinogonia (Pseudolampetisfasciata metallica (Cobos, 1969) and Ectinogonia metallica Fairmaire, 1856—the latter now considered a synonym of E. speciosa (Germain, 1856). In taxonomic nomenclature, two taxa in the same genus cannot bear the same name—a situation known as homonymy. In such cases, the older name has priority and the younger name, in this case Cobos’, must be replaced. This was done by Bellamy (2006), who proposed the new name moorei for this subspecies, resulting in the name Ectinogonia (Pseudolampetis) fasciata moorei Bellamy, 2006. To bring some level of absurdity to the situation, the subgenus Pseudolampetis was subsequently raised to full genus rank, being listed as such in the recent world catalogue (Bellamy 2008), and since Cobos’ name was not originally proposed within the genus Ectinogonia it no longer competes with Germain’s name in that genus. As a result, there is no homonymy and Cobos’ original name must once again stand as Pseudolampetis fasciata metallica (Cobos, 1969), while Bellamy’s replacement name must be regarded as unnecessary. This fact seems to have been overlooked when Pseudolampetis was raised to genus rank, as Cobos’ taxon is still listed in the world catalogue as “Pseudolampetis fasciata moorei (Bellamy, 2006)”! This situation is a perfect example of just how complicated these situations can be to identify, track, and update. The type locality for the unique female is given as “Chagual, 1.200 metros de altitud, Rio Marañón, en el Perú, VIII-1953 (B. Fernández leg.)”.

Subfamily BUPRESTINAE

Tribe STIGMODERINI

Conognatha rufiventris weyrauchi Cobos, 1969

Conognatha rufiventris weyrauchi Cobos, 1969. The taxon is now considered a synonym of Conognatha abdominalis Waterhouse, 1912.

Insufficient grounds. Cobos (1969) regarded this specimen from Peru as subspecifically distinct from Conognatha rufiventris Waterhouse, 1912 from Brazil based on a suite of subtle character differences and named the taxon Conognatha rufiventris weyrauchi in honor of Prof. W. Weyrauch, who made made the holotype specimen available to him for study. Moore & Lander (2010) considered that the taxon did not represent C. rufiventris, but rather was a uniquely colored specimen of Conognatha abdominalis Waterhouse, 1912. The holotype is a male with the type locality given as “del Valle de Chatichamayo, a 1.200 m., en Peru (J. Schuiike leg.)”.

Conognatha amphititres Cobos, 1958 (syn. of Buprestis amoena Kirby, 1818; currently placed in Conognatha)

Conognatha amoena amphititres Cobos, 1958. The taxon is now considered a synonym of C. amoena (Kirby, 1818).

Insufficient grounds—part II. Cobos (1958) regarded this specimen from Brazil as subspecifically distinct from C. amoena (Kirby, 1818—originally described in the genus Buprestis) based on subtle characters and gave it the name Conognatha amoena amphititres (no etymology was given for the subspecies name). Moore & Lander (2006) regarded these differences as insufficient for subspecies status and placed the taxon as a synonym of the parent species. The holotype is thought to be a female with the type locality given as “Rio de Janeiro (Brasil)”.

Tribe CHRYSOBOTHRINI

Colobogaster weyrauchi Cobos, 1966

Colobogaster weyrauchi Cobos, 1966

Cobos (1966) described Colobogaster weyrauchi from Peru and named it after the collector, relating it to the widespread Colobogaster cyanitarsis Gory & Laporte, 1837. The type locality was given as “Pucallpá, 200 m. alt., Perú (W. Weyrauch coll. I-1948)”.

Subfamily AGRILINAE

Tribe CORAEBINI

Dismorpha grandis Cobos, 1990

Dismorpha grandis Cobos, 1990

Cobos (1990) described Dismorpha grandis from Argentina in his very last buprestid publication, stating that the species had the appearance of an enormous D. irrorata (Gory & Laporte, 1839) (thus, the name “grandis“). The holotype is a male with the type locality given as “Bemberg, Misiones, Argentina (Exp. Hayward-Willink-Golbach: 12-29-I-1945)”.

Tribe AGRILINI

Diadorina golbachi Cobos, 1974 (monotypic)

Diadorina golbachi Cobos, 1974 (monotypic)

Cobos (1974) described Diadorina golbachi from Argentina as the only member (and thus the type species) of the new genus Diadorina (the genus is still regarded as monotypic), naming it in honor of the collector. The holotype specimen is a female with the type locality given as “La Tigres, Santiago del Estero, Argentina (R. Golbaeh coll. 11-16-1-1970)”.

Tribe TRACHEINI

Pachyshelus huallaga Cobos 1969 (correct spelling is huallagus)

Pachyshelus huallaga Cobos, 1969

Cobos (1969) described and named this species after the river at the type locality in Peru. He related it to Pachyschelus atratus Kerremans, 1896 from Brazil and northern Argentina, stating that it differed by its distinct and less brilliant coloration and other features. Since the genus name is considered masculine, the correct species name is “Pachyschelus huallagus Cobos, 1969″. The unique holotype is a female with the type locality given as “Tingo María, Rio Huallaga, 700 metros de altitud, Peru, X-1946 (W. Weyrauch leg.)”.

Pachyschelus weyrauchi Cobos, 1959

Pachyschelus weyrauchi Cobos, 1969

Cobos (1969) described Pachyschelus weyrauchi from Ecuador and named it in honor of its collector. He related the unique male to Pachyschelus aeneicollis (Kirsch, 1873) from Peru and Bolivia, citing differences in coloration, body shape, and surface sculpture. The type locality was given as “El Puyo, 900 metros de altitud, Ecuador, 10-IV-1958 (W. Weyrauch leg.)”.

There are two additional Buprestidae type specimens in the collection (Colobogaster pizarroi Cobos, 1966 and Hylaeogena cognathoides Cobos, 1969), but they are in another drawer that we did not find immediately and, thus, I did not have a chance to photograph them. My apologies!

REFERENCES:

Bellamy, C. L. 2006. Nomenclatural notes and corrections in Buprestidae (Coleoptera). The Pan-Pacific Entomologist 81(3/4):145–158 [pdf].

Bellamy, C. L. 2008. A World Catalogue and Bibliography of the Jewel Beetles (Coleoptera: Buprestoidea). Volume 2: Chrysochroinae: Sphenopterini through Buprestinae: Stigmoderini. Pensoft Series Faunistica No. 77, pp. 626–1260, Pensoft Publishers, Sofia-Moscow [details & links].

Cobos, A. 1966. Notas sobre Bupréstidos neotropicales. XV: Tres especies nuevas de Colobogaster Sol. (Coleoptera). EOS, Revista Española de Entomología 41(2-3):205–214 [pdf].

Cobos, A. 1969. Notas sobre Bupréstidos neotropicales XVII. Especies y subespecies nuevas (Coleoptera). EOS, Revista Española de Entomología 44(1968):19–43 [pdf].

Cobos, A. 1958. Tercera nota sobre Bupréstidos (Ins. Coleoptera) neotropicales descripciónes y rectificaciónes diversas. Acta Zoologica Lilloana 15:83–102 [pdf].

Cobos, A. 1973. Revisión del género Tylauchenia Burm., y afines (Coleoptera, Buprestidae). Archivos del Instituto de Aclimatacion 18:147–173 [pdf].

Cobos, A. 1974. Notas sobre Bupréstidos neotropicales, XIX. El género Amorphosternus H. Deyrolle y afines. Archivos de Instituto de Aclimatación 19:65–81 [pdf].

Cobos, A. 1990. Revisión del género Dismorpha Gistel (Coleoptera, Buprestidae). Revista Brasileira de Entomología 34(3):539–559 [pdf].

Moore Rodriguez, T. 1986. Contribución al conocimiento de los Buprestidos neotropicales (Coleoptera: Buprestidae). Revista Chilena de Entomología 13:21–29 [BioStor].

Moore Rodriguez, T. & T. Lander. 2010. Revision du genre Conognatha. Edition Magellanes 24:1–172 [introduction and generic discussion in French and Spanish; keys to species in English, French and Spanish] [order information].

© Ted C. MacRae 2015

“Picudo negro” (black weevil) on soybean in Argentina

During my recent tour of soybean fields in Argentina, I traveled north to Tucumán Province and met with entomologists at the Estación Experimental Agroindustrial Obispo Columbre (“Obispo Columbre Agricultural Experiment Station”). This provincial station, established more than 100 years ago (1909), conducts research on agricultural and production technology for the Tucumán agricultural region. Focus crops include sugarcane, citrus, and grain—primarily soybean, corn, wheat, and dry beans, with research activities ranging from basic biological studies on emerging pests (such as Rhyssomatus subtilis, featured here) and Helicoverpa armigera (recently discovered in Brazil and now in northern Argentina) to resistance monitoring for transgenic crop target pests such as Spodoptera frugiperda, Helicoverpa zea, and Diatraea saccharalis.

Rhysommatus subtilis is a significant regional pest of soybean in Tucumán Province.

Figure 1. Rhysommatus subtilis is a significant regional pest of soybean in Tucumán Province.

In recent years the laboratory has had a dedicated effort to characterize the biology and economic impact of R. subtilis on soybean (Fig. 1). Although practically limited to soybean growing regions in Tucumán Province, this insect has increased greatly in importance within that area in recent years along with two other weevils: Sternechus subsignatus (picudo grande, or “big weevil”) and Promecops carinicollis (picudo chico, or “little weevil”) (Casmús et al. 2010). Of the three species, S. subsignatus is perhaps the most serious because of its stem boring habit that can result in stand loss, while P. carinicollis is the least because its feeding is largely limited to leaves. Rhyssomatus subtilis is intermediate in importance, primarily due to larval feeding within developing pods.

Adults feed by clipping leaf petioles. The impact is minor, but it is a characteristic sign of adult presence.

Figure 2. Adults feed by clipping leaf petioles. The impact is minor but signals adult presence.

I have not yet seen S. subsignatus in soybean fields in the area, but I saw P. carinicollis during last year’s tour (see this post) and encountered R. subtilis at several locations during this year’s tour. Rhyssomatus subtilis presence in soybean can be detected even before the adults are noticed by the occurrence of clipped leaflets (Fig. 2), which is caused by adults feeding on leaf petioles.

Adult females chew a small hole into the wall of the developing pod, not to feed but for oviposition

Figure 3. Adult females chew small holes into developing pods, not to feed but for oviposition.

Leaf feeding has little if any impact on the crop; however, as the crop enters pod development stages of growth adult females begin chewing small holes in the pod walls (Fig. 3), not for feeding but for oviposition. Eggs are laid singly in the pod (Fig. 4), with larvae (Fig. 5) feeding on the developing seeds within.

Eggs are laid singly inside the pod.

Figure 4. Eggs are laid singly inside the pod.

This manner of feeding by the larva not only directly impacts yield but also hampers efforts to control active infestations by preventing contact with foliar-applied insecticides. Eventually the larvae mature, exit the pod, and drop to the soil where they burrow, pupate, and emerge as adults during the next cropping season while plants are still in early to mid-vegetative stages of growth.

This neonate larva has just hatched and will feed within the pod on developing seeds.

Figure 5. This neonate larva has just hatched and will feed within the pod on developing seeds.

Management techniques include rotation with grass crops to reduce populations (the weevil is oligophagous on soybean and dry beans), use of insecticide seed treatments to control adults during early vegetative stages of growth, and subsequent use of foliar insecticide applications if adults remain after the effect of seed treatments begins to diminish.

REFERENCE:

Casmús, A., M. G. Socías, L. Cazado, G. Gastaminza, C. Prado, E. Escobar, A. Rovati, E. Willink, M. Devani & R. Avila. 2010. El picudo negro de la vaina de soja en el NOA. Estación Experimental Agroindustrial Obispo Columbre, Tucumán, Argentina, 8 pp.

Copyright © Ted C. MacRae 2014

Tortoise beetles on the job

Back in late February and early March I did my annual tour through the soybean growing regions of central and northern Argentina to look at insect efficacy trials (pretty amazing to me still when I think about it—I actually get paid to spend time in Argentina looking for insects!). Normally on such trips there is no shortage of soybean insects to occupy my attentions—of all the large-acre row crops, soybean probably has the greatest diversity of insect associates, and in South America it is rare for any soybean field to not experience pressure from at least one of them. Soybeans, however, are not the only plants that occur in soybean fields—there are also weeds, many of which also have their own suite of insect associates. Sometimes these weed-associated insects can be even more interesting than the soybean insects I’m look for.

Botanochara angulata?

Botanochara angulata? mating pair | Córdoba Prov., Argentina

On this particular day, as I walked through a soybean field in central Córdoba Province I noticed distinctive red and black tortoise beetles (family Chrysomelidae, subfamily Cassidinae) on some of the plants. I thought it odd that tortoise beetles would be on soybean, as I’m not aware of any soybean associates in the group. A closer look, however, quickly revealed that the beetles were not on the soybean plants themselves, but rather on vines that were weaving their way through the plants. The plant was akin to bindweed and obviously a member of the same plant family (Convolvulaceae), but none of my field mates knew which of the many weedy species of the family that occur in Argentina that this particular plant represented. Species of Convolvulaceae are, of course, fed upon by a great diversity of tortoise beetles—always a treat for this coleopterist to see, and it was all I could do to concentrate on the task at hand and finish doing what I needed to do so I could turn my attention to finding and photographing some of these beetles. Once I began photographing them I found them surprisingly uncooperative (not my normal experience with tortoise beetles), but I soon found a mating pair that was a little more cooperative (probably because they were mating), with the above photo being my favorite of the bunch.

Paraselenis tersa?

Paraselenis tersa? female guarding her eggs | Córdoba Prov., Argentina

As I was searching for beetles to photograph, I encountered some yellow tortoise beetles associated with the same plant but that I had not noticed earlier. Unlike the conspicuously red and black colored species (which seems to best match Botanochara angulata according to Cassidinae of the World), the yellow species (which I presume represents Paraselenis tersa, also ID’d using the same site) seemed almost cryptically colored. When I finished taking photographs of B. angulata, I began searching for a P. tersa to photograph and encountered the female in the above photograph guarding her eggs—score!

Undetermined cassidine larvae.

A single tortoise beetle larva was encountered.

Tortoise beetle larvae are always a delight to see as well—their dinosaurian armature and fecal adornments, both obviously designed to dissuade potential predators, form one of the most ironic defensive combinations one can find. If additional tactics become necessary, they are among the few insects that are known to actually “circle the wagons” (the technical term for this being “cycloalexy“). While I only found a single larvae (of which species I don’t know), its presence seems to further suggest that at least one of the species represented an actively developing population and that the adults I found were not just hangers-on putzing around until winter (such as it is in central Argentina) forced them to shut down for the season.

Undetermined cassidine larva.

Spiky spines and a pile of poop make formidable defenses.

My impression is that tortoise beetles are by-and-large noxious to predators, thus explaining why so many species in the group exhibit aposematic coloration. However, the apparent cryptic coloration of Paraselenis makes me wonder if this is not universally true. It seems especially odd for two species to feed on the exact same species of plant but only one of the species to be noxious, which leads me to even more questions about how two species feeding on the same plant at the same time avoid direct competition with each other. I wondered if perhaps one species was on the wax while the other was on the wane (late February is well along into the latter part of the season in central Argentina), but the fact that both species were involved in reproductive activities (mating in Botanochara and egg guarding in Paraselenis) suggests this was not the case.

Ted MacRae photographing tortoise beetles.

A candid photo of me photographing tortoise beetles (and revealing my technique for getting “blue sky” background photographs).

© Ted C. MacRae 2014

Tiger beetles in Argentina’s Chaco forest

The day after I photographed Brasiella argentata on the mud/san banks of the Rio Paraná in Corrientes, Argentina, I decided to drive westward into the heart of Chaco Province. The destination: Chaco National Park, where some of the best remaining examples of the original “Gran Chaco” remain. Once covering nearly a million square kilometers in northern Argentina, Paraguay and Bolivia, this distinctive ecoregion has been largely converted to a vast, hot sea of cotton fields and mesquite fence-rows. A unique plant community in the Gran Chaco is the quebracho forest that takes its name from quebracho colorado chaqueño (Schinopsis balansae)—a tall, massively-trunked tree (related to, of all things, poison ivy!) with beautiful red wood that has been logged relentlessly wherever it occurs. Chaco National Forest is unique for the largely intact example of this forest it preserves and the mature quebracho trees that it contains.

Odontocheila chrysis | Chaco National Park, Argentina

Odontocheila chrysis (Fabricius, 1801) | Chaco National Park, Argentina

Insect life was not abundant as I walked the dark forest path. The lateness of the season (early April) and long-enduring drought occurring in the region had taken their toll, and I was content to see just about anything. At one point, a flash of movement caught my eye, and as I scanned the forest floor in the area where I had seen it, the familiar silhouette of a Golden Forest Tiger Beetle—Odontocheila chrysis (Fabricius, 1801)—became visible. I was already familiar with this species, having seen fairly good numbers of them at another location further east during my first visit to the area 12 years earlier. Long-legged and fast-flying, this tiger beetle occurs throughout much of South America, where it lives in more shaded areas of forest clear-cuts, secondary forests, savannas, and open scrublands (Erwin & Pearson 2008). The ground-dwelling adults are known to congregate along paths and at large openings on the forest floor, and indeed I had seen them in their greatest numbers on a shaded dirt road around the margins of a temporary mud puddle. When disturbed, the wary adults fly up from the forest floor to land in adjacent bare area of substrate or on the leaves of understory plants.

Superposition eyes are adapted to the dark forest environment in which this species lives.

Superposition eyes are an adaptation to the dark forest environment where this species lives.

I faced a bit of a quandary when I saw this individual—do I collect it as a voucher and studio photograph backup, or do I go ahead and try to get the much more desirable in situ photograph of an unconfined adult in its native habitat. Considering that I had already collected a sufficient number during my earlier trip, I opted for the latter. I am fortunate that I got these two quite acceptable photographs before the adult flashed away in the blink of an eye right after I took the second shot, because I never saw another one the rest of the day or even the trip.  

An interesting feature of O. chrysis is its superposition eyes. In such eyes, each rhabdom (light sensitive unit) in the compound eye receives light through many ommatidial facets. This is in contrast to apposition compound eyes, where each rhabdom receives light from only a single facet. Superposition eyes are designed to increase photon capture, which is an advantage in the dark forest habitats where this beetle prefers to live (Brännström 1999).

Brasiella argentata | Chaco National Park, Argentina

Brasiella argentata (Fabricius, 1801) | Chaco National Park, Argentina

Shortly after photographing O. chrysis, I came upon a small opening where the path was a little wider and sunnier and the soil a little sandier and drier. Immediately I saw the small, zippy flits of the same tiger beetle species I had photographed the previous day on the banks of the Rio Paraná—Brasiella argentata. I could not find in the literature whether this species has superposition or apposition compound eyes, but considering that the species occur in great numbers on sunny river banks and that the few individuals I saw in the forest were in a sunny opening, I’m betting it’s the latter.

I couldn’t help but make another attempt to photograph this species, considering the difficulty I’d had the previous day (and that I wasn’t completely satisfied with any of the photos that I had obtained). More good fortune, despite there being only a few individuals to work with, as I managed to get the above photograph, which I consider far better than any that I already had. These beetles, too, quickly disappeared, and I never saw them again, but knowing I had the photos that I wanted made that okay.

Habitat for Odontocheila chrysis and Brasiella argentata

Quebracho forest habitat for Odontocheila chrysis and Brasiella argentata.

REFERENCES:

Brännström, P. A. 1999. Visual ecology of insect superposition eyes. Unpublished Ph.D. Dissertation, Lund University, 142 pp. [abstract].

Erwin, T. L. & D. L. Pearson. 2008. A Treatise on the Western Hemisphere Caraboidea (Coleoptera). Their classification, distributions, and ways of life. Volume II (Carabidae-Nebriiformes 2-Cicindelitae). Pensoft Series Faunistica 84. Pensoft Publishers, Sofia, 400 pp. [Amazon descriptionbook review].

© Ted C. MacRae 2014

Stalking tigers in Argentina

Brasiella argentata

Brasiella argentata | banks of Rio Paraná, Corrrientes, Argentina

Most of you know that I have spent a lot of time in Argentina over the years, and while most of my time there has been for work I have had a fair bit of opportunity to collect insects as well. This includes tiger beetles, and in fact I recall one trip some years ago during which I spent the better part of a week chasing tigers in northeastern Argentina around Corrientes and west into Chaco Province. I think I collected maybe a dozen species or so—some in great numbers and others not, and with the help of tiger beetle expert David Brzoska I’ve managed to put names on most of the material. Despite this, however, I’ve never actually posted any photos of tiger beetles from Argentina here on BitB. I guess the main reason for this is that my efforts to photograph tiger beetles is still a relatively new pursuit (compared to the time that I’ve been going to Argentina), and most of my luck with tiger beetles in Argentina has preceded my time with a camera. The other reason for the delay is that, while I have managed to photograph a few tiger beetles in Argentina, I’ve only recently been able to determine their identity (and you all know how I dislike posting photos of unidentified insects). Well, time to change that, and for this post I am featuring the very first tiger beetle that I was able to photograph in Argentina—the aptly named Brasiella argentata.

Banks of Rio Paraná, habitat for Brasiella argentata.

Banks of Rio Paraná, habitat for Brasiella argentata.

The individuals in this post were photographed on 1 April 2011 during the early part of a week-long visit to Corrientes and neighboring Chaco Province in northern Argentina. Remember, this is the southern hemisphere, so early April is way late in the season and, in this part of Argentina, typically on the back end of a very long dry period. Still, it is far enough north to be borderline subtropical climate, and with the stifling heat it could, for all intents and purposes, have been the middle of summer. I knew tiger beetles could be found along the banks of the Rio Paraná, as I had collected them there during my trip some 10 years previous, so in late morning of my first day after arrival in the city I kitted up and walked down to the river. Sand and mud beaches are not plentiful along the mostly rocky shoreline, and I was perturbed to see the area where I had collected during my last visit had since been “developed.” Nevertheless, I found promising-looking habitat a short distance further north and walked to its moister edges (photo above). I saw nothing at first, but eventually I came to a small, moist drainage where the sand was mixed with more mud, and there they were! It took a little bit of looking, as this species is quite small—adults average only ~7 mm in length, and despite the impression you may get from these photos they are well camouflaged to match the color of the wet, muddy sand and, thus, difficult to see before they take flight and again after they land.

An individual sits long enough to allow a few close, lateral profile shots.

Brasiella argentata is one of the most widely distributed Neotropical species of tiger beetles, occurring from Panama and the West Indies south to Peru and Argentina (Cassola & Pearson 2001). Numerous subspecies have been described from throughout its range, but in truth it seems to actually be a “species swarm” comprised of multiple species, many of which can only be determined by examination of characters contained within the male aedeagus (Sumlin 1979). The genus Brasiella itself, like many others, was until recently considered to be a subgenus of Cicindela, but the distinctiveness of these mostly small (Pearson et al. 2007 refer to them as “Little Tiger Beetles”), cursorial (running) beetles has been recognized in most of the more recent comprehensive treatises (e.g., Cassola & Pearson 2001, Erwin & Pearson 2008). Unlike most of its related genera (subtribe Cicindelina), Brasiella is almost exclusively Neotropical in distribution—only one of its 45 species, B. wickhami, reaches the U.S. in southern Arizona (Pearson et al. 2007).

Brasiella argentata

The only photo I managed looking towards the front of an individual.

If their smallness must be recognized, so must their running abilities. This was one of the most difficult species I’ve ever attempted to photograph, and with those difficulties added to the heat of the day and its “perfect storm” habitat it’s a wonder I got any photographs at all. It was a good half hour before I even got the first photo (top), and another hour and a half of effort was required before I managed to get a selection of photos that included a good, close lateral profile shot (middle). As is often the case with very wary tiger beetles, frontal portraits were almost impossible due to their persistent efforts to flee, so I feel fortunate to have managed the last photo. It’s not as close as I typically like to get, but I am pleased with the composition and also the fact that it shows the species’ truncate labrum—a key character.

REFERENCES:

Cassola, F. & D. L. Pearson. 2001. Neotropical tiger beetles (Coleoptera: Cicindelidae): Checklist and biogeography. Biota Colombiana 2:3–24 [pdf].

Erwin, T. L. & D. L. Pearson. 2008. A Treatise on the Western Hemisphere Caraboidea (Coleoptera). Their classification, distributions, and ways of life. Volume II (Carabidae-Nebriiformes 2-Cicindelitae). Pensoft Series Faunistica 84. Pensoft Publishers, Sofia, 400 pp [Amazon description, book review].

Pearson, D. L., C. B. Knisley & C. J. Kazilek. 2006. A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press, New York, 227 pp. [Oxford description].

Sumlin, W. D., III 1979. A brief review of the genus Cicindela of Argentina (Coleoptera: Cicindelidae). Journal of the New York Entomological Society 87(2):98–117 [JSTOR].

Copyright Ted C. MacRae 2013

A belated Happy Birthday

It seems that November 24th came and went without me even realizing that BitB turned six years old that day! Six years—wow, has it really been that long? I guess forgetting birthdays officially puts me in the old-timer camp (both as a person and as a blogger). No fanfare or celebration. Instead, I blithely wrote my 778th post (Q: How do you photograph cactus beetles?) and carried on as usual.

I guess it’s too late now to make a big deal of it, but I will make the observation that November 2013, with its 15 posts, was one of my heaviest blogging months ever (the most since 18 posts in December 2012 and the overall high of 21 in April 2010). This may come as a surprise to those who have heard me grouse periodically about the decline of blogging, both of my blog in particular and as a platform in general. It’s a different world than it was when I started BitB—Twitter and Facebook have taken over much of the social interaction that used to take place on blogs, relegating the latter primarily to satisfying a small but persistent niche demand for long-content. Throughout the course of these changes, however, motivation to blog still comes to me consistently and often. Mostly it seems to be an internal need to express myself, but the occasional and very much appreciated feedback in the form of comments and emails also helps. So, with that, thank you for the past six years, and here’s looking at the next six!

Enough blather—here are a few colorful net-winged beetles in the genus Calopteron (family Lycidae) to help with the celebration. They were photographed in northern Argentina (Chaco Province) in April 2012 while visiting flowers of Chilean goldenrod (Solidago chilensis). I’m not sure if they represent more than one species, as the taxonomy of the genus in the Neotropics appears to be very poorly known at this time—if so it would seem there exists in this area a mimicry complex that is ripe for study.

Calopteron sp. on flowers of Solidago chilensis| Chaco Province, Argentina

Calopteron sp. on flowers of Solidago chilensis | Chaco Province, Argentina

Calopteron sp. on flowers of Solidago chilensis| Chaco Province, Argentina

Calopteron sp. on flowers of Solidago chilensis | Chaco Province, Argentina

Calopteron sp. on flowers of Solidago chilensis| Chaco Province, Argentina

Calopteron sp. on flowers of Solidago chilensis | Chaco Province, Argentina

Copyright © Ted C. MacRae 2013