Theognete Champion 1902

Anderson, Robert S., 2010, A taxonomic monograph of the Middle American leaf-litter inhabiting weevil genus Theognete Champion (Coleoptera: Curculionidae; Molytinae; Lymantini) 2458, Zootaxa 2458 (1), pp. 1-127 : 9-11

Theognete Champion 1902

Theognete Champion, 1902:97 ; Dalla Torre et al. 1932:86 (checklist); Blackwelder 1947:823 (checklist); O'Brien & Wibmer 1982:85 (checklist); Alonso-Zarazaga & Lyal 1999:205 (catalog).

Type species: Theognete laevis Champion 1902:97 , by monotypy. Gender feminine.

Diagnosis. Easily distinguishable among Lymantini by generally oval form of body; black, often shining cuticle with vestiture varying from sparse and recumbent to dense and erect, concentrated in some species into distinct patches or tufts; individual scales simple to plumose; middle and hind coxae widely to very widely separated, metasternum (and mesosternum in some species) markedly and variously excavate medially, excavation(s) within with various extent of fine pilose vestiture; females with sternite VIII broadly U-shaped, lacking basal apodeme.

Description. Length, 2.3–6.0 mm. Width, 1.2–3.6 mm. Cuticle black to rufous in some species (brown in teneral specimens), matte or shiny and polished, with or without prominent microsculpture. Vestiture present, of various form and length; simple to deeply plumose, erect to recumbent; variously distributed, concentrated in some species into distinct patches or tufts. Rostrum separated immediately behind eyes from head by deep transverse impression; dorsally and laterally shallowly punctate; punctures slightly smaller towards apex, variously elongate-oval and coalescent above scrobe in front of eye, obscured in males of some species by fine, dense pilosity, ventrally variously punctate anteriorly; punctures with recumbent, small, fine seta, between eyes in some species with larger recumbent to suberect plumose scales; sexually dimorphic: in lateral view in males more or less straight to very slightly arcuate from base to point of antennal insertion, then variously deflexed and flattened to apex, in females more or less evenly arcuate throughout or slightly deflexed at point of antennal insertion; in dorsal view in males with scrobes broadly visible, expanded at point of antennal insertion to apex, in females with scrobes not or very narrowly visible, of more or less uniform width throughout to very slightly wider at apex; point of antennal insertion in male at more or less apical one-third to onequarter, in female at slightly beyond midlength to apical one-third. Scrobes deep, lateral, descended posteriorly immediately in front of eye, narrowly separated by posterior extension of gular area. Eyes present, moderately convex; situated dorsolaterally on rostrum at base; coarsely facetted, each eye with less than 30 facets; variously separated dorsally, not contiguous. Head round, globular; lacking punctation or vestiture. Antennae with funicle composed of seven articles (six in one species); articles 1–6 short, robust, slightly longer than wide (basally) to slightly wider than long (apically), successively wider towards apex; 1 and 2 lacking vestiture and shining; 7 closely appressed to club and distinctly wider than 6. Club with basal article shiny, glabrous, apical article densely setose, subequal in length. Pronotum robust; variously and irregularly punctate; each puncture bearing scale or seta, scales of various size and form; in dorsal view with shape various; tubulate, constricted laterally and dorsally (less so in many species) at subapex to various extent; variously constricted and impressed also in basolateral region; widest at from midlength to apical one-third, more or less half width of elytra. Elytra fused, elongate-oval to broadly oval in dorsal view; stria generally not impressed (but striae 1–3 to various extent in some species), demarcated by line of fine, small, recumbent setae in various species or by variously impressed, large punctures in others; interstrial regions with vestiture of various form, size and extent (sparse or lacking in a few species), tuberculate (markedly so) in some species; punctation various, lacking or very sparse and shallow in most species; variously impressed and/or coarsely and deeply punctate laterally at subapex (adjacent to base of ventrite V) in species with otherwise impunctate elytra. Wings absent. Scutellum absent. Legs moderately long and narrow, not robust. Coxae with various extent of dense, fine pilosity and sparse, longer, coarser, suberect, recurved scales; each coxa with or without single, long, erect, fine seta; front coxae very narrowly to very widely separated, middle and especially hind coxae very widely so. Femora simple, widest at approximately apical one-third, not markedly clavate; punctation and vestiture various, denser towards apex. Tibiae more or less straight to slightly bowed inwardly (hind tibiae markely so in males of some species), not distinctly spatulate; punctation and vestiture various, fine pilosity present, dense throughout in most species; uncus moderately large, moderately curved inwardly; apex of inner margin with variously developed small tooth; apical comb short, of fine brownish spines. Tarsi fine, small, four-segmented; segments 1–3 subequal in length and width; 3 shallowly bilobed; 4 slightly longer than 3; claws simple, minute; ventral tarsal pilosity variously developed. Prosternum immediately anteriorly of front coxae variously elevated, tumescent or shelf-like; meso- and metasternum markedly modified, very short, the latter (and mesosternum in some species) markedly and variously excavate medially; excavation(s) within with various extent of fine pilose vestiture, metasternum laterally, anteriorly of hind coxae, variously swollen, impunctate and glabrous; mesepisternum and mesepimeron impunctate, glabrous; metepisternum and metepimeron absent. Abdomen with five visible ventrites; 1 and 2 fused, the others free; 1 with broad anterior projection between hind coxae, flat to anteriorly declivious, medially longer than 2 but laterally subequal in length, variously punctate and with various appressed vestiture; 3 and 4 very short, subequal in length, impunctate; 5 more or less twice as long as 3 and 4 combined, variously punctate, sexually dimorphic, variously swollen and impressed, punctures large and deep. Genitalia of female with sternite VIII broadly Ushaped, lacking basal apodeme, tergite VIII broadly triangular in shape, apical margin simple, emarginated or variously cleft medially, not serrate or toothed, pygidium with apical margin simple, very shallowly emarginate at most, coxites lacking styli, spermatheca small and compact. Genitalia of male with aedeagus long and slender to short and robust, basal arms (struts) long, generally longer than aedeagal body, apex various from broadly truncate to acuminate, in lateral view more or less straight (except at apex where deflexed) to slightly uniformly arcuate ventrally; internal sac long, extended to mid length (or beyond) of basal arms, generally with some to extensive sclerotization.

Distribution. Theognete is most diverse in México (78 species), occurring throughout the Sierra Madre Oriental from Tamaulipas south to the eastern portion of the Transverse Volcanic Belt and into the Sierra Madre de Oaxaca, in the Sierra Madre del Sur and from the mountains of Chiapas into Guatemala (6 species), Honduras (10 species) and El Salvador (3 species). The species numbers in these countries and their regions are detailed in Table 1. Theognete is not known from the Sierra Madre Occidental in México nor from Central America south of Honduras, no specimens having been found in Costa Rica and Panama despite extensive collections there. The few collections made in Nicaragua so far also did not yield any specimens, but the genus is expected to be found with more extensive sampling in the mountains in the northern part of the country along the border with Honduras.

Derivation of generic name. Champion (1902) did not indicate the derivation of the name Theognete but it appears to be derived from the Greek theos, meaning god, and gnetos, meaning born. In Greek mythology ‘Theognete’ (“born of the god(s)”) was one of the possible mothers of Jason, the Argonaut.

Natural history. No details are available on the natural history of any Theognete species. Adults have been collected almost exclusively in berlese or winkler extractions of sifted leaf litter and other ground substrate debris. Specimens of T. hesmos have been collected under wood chips of recently cut oaks and on dead branches lying on the ground. Immature stages are unknown. Given what is known of the habits of related taxa, it is likely that the larvae mine in dead, decaying wood or other plant debris on the forest floor. A single specimen of T. howdenorum was collected in the stomach of Bufo valliceps Wiegmann at Choapan, Oaxaca (see Goldman 1951: 211).

Nearly all species are associated with a variety of montane mesic forest habitats, although at least three species occur in lower elevation evergreen forest habitat. Species have been collected at elevations ranging from almost sea level to 3000m.

Characters of taxonomic and potential phylogenetic significance. In subdividing the genus Theognete into recognizable, manageable and meaningful species groups, it has proven necessary to emphasize the taxonomic (and potential phylogenetic) value of certain characters. In the treatment of Theognete provided here, the structure of the thoracic sterna is considered of primary importance in resolving the placement of species into species groups. Other important characters include the extent, form and pattern of pronotal and elytral vestiture, sculpture and punctation; the impression in the posterolateral area of the elytra; the pattern and form of punctures on ventrite 5; and the structure of the male genitalia.