Escarabajos (Coleoptera) de Peru: Un muestreo de las familias. Pythidae Solier, 1834.
The Peruvian fauna of Pythidae is reviewed as part of the Caroline Chaboo 'Beetles of Peru project' (2010-present). The relatively few members of this family were widely dispersed among several other families of Tenebrionoidea (e.g. Melandryidae, Salpingidae) until relatively recently (Pollock & Lawrence 1995). The family has temperate northern (5 genera, 14 species) and southern (1 genus, 2 species) hemisphere constituent taxa, with one genus, Ischyomius Chevrolat, represented in the Neotropics by 8 species (Pollock 1998, 2007, 2009). Contrary to the major differences in the adults of the various genera of Pythidae, the larval stages show more structural similarities to one another, particularly in the structure of the urogomphal plate (Pollock 2010). Though the genus was revised by Pollock (1998), additional undescribed species continue to accumulate and it seems very likely that additional species of Ischyomius will be added to the Peruvian fauna of Pythidae. Relevant literature, habitats, biology (including association with Zingiberales), and collecting methods are summarized to aid future field collections.
Recognition.--This small family of 7 genera and ~25 species worldwide (Pollock 2010) is difficult to characterize, as there is considerable structural diversity among the constituent genera. Despite the major structural differences between pythid genera, species within genera show a high degree of similarity. All known species of Ischyomius exhibit the same general facies: body elongate (length 5.9-13.4 mm; ratio of length: maximum width = 3.5-4.3), slightly flattened to relatively convex dorsally; eyes large, protruding; pronotum wide, at least indistinctly explanate laterally; elytra widest anteriorly, distinctly tapered posteriorly, in most species with apices produced into spines (Pollock 1998, Fig. 1; Pollock 2010, Fig. 11.23.1.D). The larval stage of Ischyomius is known (author's collection and material borrowed from Jim McClarin) but is yet undescribed; it exhibits the following general features: body elongate, parallel-sided, only slightly flattened dorsoventrally; head with 5 stemmata (3 anterior and 2 posterior); urogomphal plate with dorsal tubercles and multiple inner teeth on urogomphi; sternite 9 with transverse row of asperities. These larval characters are very similar to those exhibited by Pytho larvae (Pollock 1991), offering even more evidence that Ischyomius properly belongs in Pythidae.
The two species currently known from Peru are keyed in Pollock (1998) and differ greatly from one another; I. bicolor differs from all other described species of Ischyomius in that it possesses short, subserrated antennomeres, very wide pronotum, and rounded (not spiniform) elytral apices. Also, almost all specimens examined exhibit a dark-colored pronotum, contrasting against the relatively more lightly-colored elytra (hence, the specific epithet "bicolor").
Material and methods
Biology, Habitat, and Collecting Methods.--The biology of this family is relatively well known (yet still with some significant gaps), compared to some other families ofTenebrionoidea. Larvae of all species of Pytho Latreille and the monotypic Priognathus monilicornis (Randall) are associated with dead and rotting conifer trees (Pollock 1991, 2010; Young 1991). Larvae of Anaplopus tuberculatus Blackburn and Sphalma quadricollis Horn were collected under dead tree bark (Pollock and Lawrence 1995; Young 1976). There is some limited information published on the adults of these taxa, but since larvae are usually in specific habitats, the most meaningful natural history information for Pythidae is derived from the larval stages.
Pollock (1998) summarized what little was known about the biology and habits of species of Ischyomius. Based on label data of examined specimens, adults of two species, I. chevrolati Champion and I. singularis Chevrolat, seem to be associated with wilted foliage of several species of Musaceae: Musa sapientum L. (banana), M. paradisiaca L. (plantain), and M. textilis Nee. Adult specimens of I. nevermanni Pollock were taken from foliage of Cryosophila (= Acanthorrhiza) warscewiczii (H. Wendt.) Bartlett and Iriartea sp. (Palmae). All type specimens of I. escalonai Pollock were collected in association with withered leaves of "Bird of Paradise" plants (Strelitzia sp., Strelitzaceae). As stated by Pollock (2009), Strelitzia was introduced to the Neotropics from its native South Africa; Strelitzaceae and Musaceae are related families within the monocot angiosperm Order Zingiberales (Kress & Hawn 1997). Samples of two species of Ischyomius larvae and adults received recently from J. McClarin were collected in/ on banana and Heliconia (Heliconiaceae), the latter also in the Zingiberales. In summary, the known information regarding larval hosts of Ischyomius points to a fairly restricted group of plant taxa within the Monocots, specifically in Zingiberales and possibly Palmae.
Adult pythids are relatively rarely collected, except when found in the same habitats as the larvae. For example, Pollock (1991) collected many adult Pytho from within pupal cells under the same dead bark where larvae were previously feeding. For Ischyomius, since larvae seem to be restricted to particular groups of plants, adults are most likely to be encountered and collected in forest areas with these same plants. Malaise and flight-intercept traps are likely to collect flying specimens, but it seems that the best way to collect adults (based on label data) is beating dead vegetation of trees of Musaceae and Palmae, or hand-collecting through examination of vegetation in which larvae occur. For example, recent samples sent to me by Jim McClarin represented both larvae and adults. A description of these newly acquired larval specimens is currently underway (Pollock, in prep.).
The following checklist is derived from a revision of the genus Ischyomius Chevrolat by Pollock (1998); the geographic distributions in Peru listed below were derived from 14 specimens deposited in the following collections:
--CAS--California Academy of Sciences, San Francisco, CA, USA (David Kavanaugh).
--CMNH--Carnegie Museum of Natural History, Pittsburgh, PA, USA (Robert Davidson).
--FMNH--Field Museum of Natural History, Chicago, IL, USA (Alfred Newton).
--MNHN--Museum National d'Histoire Naturelle, Paris, France (Nicole Berti).
--NMNH--National Musem of Natural History, Smithsonian Institution, Washington, D.C., USA (G. House).
Checklist of Pythidae of Peru
PYTHIDAE SOLIER, 1834 ISCHYOMIUS Chevrolat, 1878
Ischyomius singularis Chevrolat, 1878
(Bolivia, Colombia, Ecuador, Peru)
Ischyomius bicolor Champion, 1916
(Brazil, Colombia, Ecuador, Peru) Ischyomius singularis
Huanuco: Yurac, 67 mi E. of Tingo Maria, 11.xii.1954, E. I. Schlinger & E. S. Ross (CAS, 1).
Lima: Callanga, no other data (FMNH, 8), (NMNH, 2).
Illustration of adult in Pollock (1998), Fig. 1A
Loreto: Iquitos, M. de Mathan (MNHN, 2).
Madre de Dios: Tambopata Wildlife Res, 30 km SW Pto. Maldonado, 12[degrees]50'S, 69[degrees]20'W; 290 m, 9.xi.1982, J. J. Anderson (CMNH, 1).
Illustration of adult in Pollock (1998), Fig. 1E
I thank Jim McClarin for sending larval and adult Ischyomius spp. collected in Ecuador, and the curators of the many collections from which specimens were borrowed during taxonomic studies on Ischyomius.
Kress, W.J. & W.J. Hahn. 1997. Zingiberanae. The bananas, gingers, and relatives. Version 01 January 1997 (under construction). http://tolweb.org/Zingiberanae/21339/1997.01.01 in The Tree of Life Web Project, http://tolweb.org.
Pollock, D.A. 1991. Natural history, classification, reconstructed phylogeny, and geographic history of Pytho Latreille (Coleoptera: Heteromera: Pythidae). Memoirs of the Entomological Society of Canada 154:1-104. doi: https://doi.org/10.4039/ entm123154fV
Pollock, D.A. 1998. Revision of the Neotropical genus Ischyomius with a discussion on its systematic position (Insecta: Coleoptera: Tenebrionoidea: Pythidae). Annals of Carnegie Museum 67(3):245-264.
Pollock, D.A. 2007. A new species of Ischyomius Chevrolat (Coleoptera: Pythidae) from Costa Rica. Coleopterists Bulletin 61(2):277-280. doi: https://doi.org/10.1649/0010-065X( 2007)61[277:ANS0IC]2.0.C0;2
Pollock, D.A. 2009. A new species of Ischyomius from Venezuela (Coleoptera, Tenebrionoidea, Pythidae) with a revised key to world species. ZooKeys 6:69-74. doi: https://doi. org/10.3897/zookeys.6.81
Pollock, D.A. 2010. Pythidae Solier, 1834, In: Leschen, R.A.B, R.G. Beutel, & J.F. Lawrence (Eds.), Coleoptera, Beetles Vol 2: Morphology and Systematics (Elateroidea, Bostrichiformia, Cucujiformia partim). De Gruyter, Berlin, pp. 708-715.
Pollock, D.A. & J.F. Lawrence. 1995. Review ofAnaplopus Blackburn (Coleoptera: Pythidae), with comments on constituents and systematics of Pythidae, In: Pakaluk, J. & S.A. Slipinski (Eds.), Biology, Phylogeny, and Classification of Coleoptera: Papers Celebrating the 80th Birthday of Roy A. Crowson. Muzeum i Instytut Zoologii PAN, Warszawa, pp. 449-472.
Young, D.K. 1976. The systematic position of Sphalma quadricollis Horn (Coleoptera: Salpingidae: Pythini) as clarified by discovery of its larva. Coleopterists Bulletin 30:227-232. http://www.jstor.org/stable/3999691
Young, D.K. 1991. Pythidae (Tenebrionoidea). Pp. 539-541, In Stehr, F.W. (Ed.), Immature Insects. Vol. 2. Kendall/Hunt Publishing Co., Dubuque, Iowa.
Darren A. Pollock
Eastern New Mexico University, Department of Biology, 1500 S. Avenue K, Portales, NM, USA, 88130.
Publicado online: 25/09/2018
Informacion sobre los autores:
The author states that there are no conflicts of interest.
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|Title Annotation:||NOTA CIENTIFICA|
|Author:||Pollock, Darren A.|
|Publication:||Revista peruana de biologia|
|Date:||Aug 1, 2018|
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