Pharaxonotha kirschii Reitter, 1875

Tang, William, Skelley, Paul E., Taylor B, Alberto S. & Salzman, Shayla, 2024, Review of Pharaxonotha Reitter (Coleoptera: Erotylidae: Pharaxonothinae) inhabiting cones of the cycad Zamia L. (Cycadales) in Panama, with descriptions of five new species, Insecta Mundi 2024 (43), pp. 1-40 : 34-36

Pharaxonotha kirschii Reitter

Figures 12A–L

Pharaxonotha kirschii Reitter 1875: 44 ~ Sharp 1900: 598; Chittenden 1911: 8–13; Hinton 1945: 189–192; Pakaluk 1988: 450; Skelley et al. 2022: 33–39.

Pharaxonotha kirschi ~ emendation of various authors.

Thallisella condradti Gorham 1898: 249 ~ Champion 1904: 36 [synonymy].

Diagnosis. A member of the kirschii group, this species is diagnosed by the uniformly dark coloration of both sexes. an enlarged antennomere XI compared to IX, the lateral pronotal marginal bead of many is weakly angulate near the middle, and the male abdominal ventrite apical tooth is more pronounced. Pharaxonotha kirschii is widespread from the southern US to Panama, is not associated with cycads. It is a known as the “Mexican grain beetle”, a pest in stored plant products which has been intercepted in many countries.

Description. [Reprinted with some modification from Skelley et al. (2022)]. Length 3.37–4.11 mm, width 1.22– 1.56 mm. General body color ( Fig. 12A–C ) dark brown to black. Dorsal surface glossy, with very short setae in puncture.

Head. Not broad, width = 0.62–0.67× pronotal width ( Fig. 12D–F ); in lateral view robust, clypeus to base of head dorsally convex; in dorsal view conical, gradually narrowed anteriorly, surface convex, coarsely punctured, average distance between closest punctures 2–3× width of puncture; head width 0.72–0.86 mm; dorsal interocular distance 0.51–0.60 mm, head width/dorsal interocular distance ratio 1.36–1.42, ventral interocular distance 0.41–0.51 mm, head width/ventral interocular distance ratio 1.68–1.79. Eye with large black facets, similar diameter of head punctures; head posterior of eye with a small tooth (temple) in dorsal profile. Antennal length slightly shorter than pronotal width, 1.4× head width; antennomere I (scape) fairly large, slightly elongate; antennomere II same length as III; IV circular; V–VII same length as IV, gradually becoming wider with VIII weakly transverse and flattened apically; club fairly large, IX and X similar in length; XI enlarged, 1.5× longer than X, globular with rounded apex. Clypeus weakly concave anteriorly, moderately punctate. Transverse occipital line [vertexal line] distinct nearly from eye to eye. Mentum and submentum coarsely punctured, 1/2–3/4× diameter of facet, distance between nearest punctures approximately 1× own diameter, each puncture with a short seta. Gular area smooth, without punctation or setae, border with submentum marked by change in punctation.

Thorax. With pronotum transversely rectangular in dorsal view, length/width ratio 0.69–0.80; with distinct marginal carina laterally and basally, anteriorly with fine marginal carina medially; dorsally flattened; anterior angles sharply rounded, projecting forward; posterior angles developed, with small denticle at angle; lateral margin weakly angulate in medial half, shallowly arcuate inward anteriorly and posteriorly; posterior margin slightly projecting medially, projection beginning approximately by pair of small, dark pores in margin located 1/4 width from posterior angles, each pore marks base of a distinct sulcus extending anteriorly onto disc 1/4 length of pronotum. Prosternum in ventral view convex, with few scattered punctures; anterior margin slightly emarginate, finely denticulate with row of long, anteriorly directed setae, longest setae approximately 1/3 length of eye; prosternal process flattened apically, expanded and truncate at apex. Hypomeron smooth, with few punctures. Scutellar shield distinctly transverse pentagonal, posterior margin weakly rounded. Elytra in dorsal view elongate, flattened dorsally; length/width 1.72–1.90, greatest width near midlength; with distinct marginal line basally; 10 complete striae of moderate puncture size; scutellary striole extending 1/5 elytral length, with 7–10 punctures; punctures of elytral striae 2× larger than pronotal punctures, striae weakly impressed; intervals of striae with fine, indistinct shallow punctures, 1/5 size of strial punctures; all punctures of elytral bearing a single very short seta; seta only visible in profile, extending slightly out of puncture. Mesoventrite with strong punctation, distance between nearest punctures approximately equal to diameter of punctures, puncture depth moderate. Metaventrite glossy, with strong lateral punctation separated by 1–2× own diameter; medial surface finely distinctly punctured, separated by 3–4× own diameter; surface medially flattened, metathoracic discrimen extending approximately 1/2 metaventrite length. Legs narrow, relatively similar in length and shape. Procoxa oval; mesocoxa globular; metacoxa transversely elongate-oval; trochanters obliquely truncate apically; femora narrowly oblong, compressed laterally; tibiae shorter than femora, weakly dilated to obliquely truncate apices; protibia with apical lateral tooth small, with complete apical fringe of very short stout spinules on straight ventral apical margin; meso- and metatibia with apical fringe of short stout spinules on anterior margin, finer setae on posterior margins.

Abdomen. Ventrite apical margin bearing short, sparse setae; all ventrites bearing moderate, shallow punctation evenly distributed across surface, distance to nearest puncture approximately 2× diameter of puncture, punctures bearing mostly reclining setae; ventrite V with setae length nearly uniformly approximately 2× diameter of puncture; I–IV each with 2 or more median pairs of longer, semi-erect sensory hairs (difficult to see in poor lighting, often abraded); male ventrite 5 with distinct denticle at apex. Male genitalia (n = 4) similar to all others in the genus with widened tegmen, elongate cylindrical median lobe, and long coiled flagellum ( Fig. 12G–J ).

Female. Similar to male. Female differs with narrow protibia and protarsus, male have weakly dilated protibia and basal protarsomeres. Female lacking apical denticle on terminal abdominal ventrite. Genital tube shortened, length past abdominal segment VIII = 1.5× width (n = 5); gonostylus set apically on gonocoxite, gonostylus length = 4–5× width ( Fig. 12K ). Spermatheca base asymmetrically rounded with curvature extending further on ventral side, basal third broadest at basal end, narrowing until unsclerotized arc at central third, apical third usually narrowing apically and usually curving abruptly near apex to a broadly rounded point ( Fig. 12L ).

Materials examined. The present location of the type (s) is unknown (not examined). The types of Thallisella condradti was collected in Vera Paz, Guatemala ( Gorham 1898), present location of type material is the NHMUK (examined) ( Skelley et al. 2022).

Additional materials examined (641). Data for all materials studied of P. kirschii are presented in Skelley et al. (2022). For Panama, we studied eight specimens here considered to be P. kirschii : PANAMA: Canal Zone, 12-V-1952, F. S. Blanton, at light (1 USNM); Chiriquí: Chiriquicito, 18-V-1996, R. Turnbow, mv + bl (1 RHTC); Coclé: 5.6 km. N. Pan Amer. Hwy, El Copé Rd, 08°37′N, 80°35′W, 7-VI-1995, J. Ashe, R. Brooks, #141 ex slash (2 SEMC); Panama: 11-15 km. N. El Llano, 13-V-1991, R. Turnbow (1 RHTC); Fort Kobbe, 27-V-1965 (1 USNM); same locality, 12-V-1985, A. J. Gilbert, P. H. Sullivan, and F. T. Hovore (1 FSCA); same locality, 23-V-1991, R. Turnbow, mv + bl (1 RHTC).

Remarks. Based on the volume of data for P. kirschii discussed in Skelley et al. (2022), it appears to be a more free-living species, occurring more commonly in leaf litter in the wild in many areas where there are no native or ornamental cycads. It is possible that cryptic species reside within the materials considered P. kirschii . We leave their analysis for future work when molecular grade materials are available for study.

Pharaxonotha kirschii was described from specimens collected in eastern Europe from Mexican plant products. Since then, it has been intercepted in many countries and mentioned many times in regional lists, regional reports, taxonomic catalogues, phylogenetic studies, keys to taxa, natural history accounts, etc., and now a growing number of websites. As the “Mexican grain beetle”, P. kirschii has been discussed in references including Chittenden (1895, 1911), Hinton (1945), Anderson (1987), Kingsolver (1987), Booth et al. (1990), and Lawrence (1991) and many others. For a further discussion of the natural and taxonomic history of this species and recently described, closely related species see Skelley et al. (2022).

Figures

Figure 12. Pharaxonotha kirschii from Costa Rica, Guanacaste Province (A–J: male). A–C) Dorsal, lateral and ventral habitus. D–F) Head, dorsal, lateral and ventral views.G) Terminal segment of male abdomen.H) Genital capsule.I) Tegmen attached to median lobe, (top to bottom) ventral and lateral views. J) Parameres of tegmen, (top to bottom) ventral and lateral views. K) Retracted ovipositor with spermatheca, ventral view. L) Spermatheca.