Yagder, Grebennikov & Anderson, 2021

Grebennikov, Vasily V. & Anderson, Robert S., 2021, Yagder serratus, a new eyeless weevil from Mexico and the non-monophyly of Brachycerinae, the evolutionary twilight zone of true weevils (Coleoptera: Curculionidae), Acta Entomologica Musei Nationalis Pragae 61 (2), pp. 363-374 : 370-372

Yagder gen. nov.

Type species. Yagder serratus sp. nov., here designated.

Diagnosis. This genus can be recognized among all weevils (Curculionoidea, including true weevils Curculionidae ) by the combination of the following characters: eye completely absent; body size larger, 3.8 mm in length (excluding rostrum and deeply inserted head), slender (ratio of length to maximal width 2.9) and parallel-sided in dorsal view; rostrum almost as long as pronotum, with deep median longitudinal furrow throughout greater portion of length both dorsally and ventrally; pronotum and elytra with large, deep round punctures, those on anterior portion of pronotum smaller, somewhat coalescent, forming striae; elytra with eight complete striae, five visible in dorsal view, strial punctures on elytra large basally, smaller towards elytral apex; tibial apices with short, stout spines, spines greatest in number and most closely spaced on front tibia; elytra with humeral angle sharp, produced anteriorly; female genitalia with gonocoxites flat, spade-like, lacking stylus, sternum 8 Y-shaped, with arms arcuate, apodeme short, broad, apically expanded.

Description. Body 3.8 mm in length (excluding rostrum and deeply inserted head), slender (ratio of length to maximal width 2.9) and parallel-sided in dorsal view; prothorax, elytra, meso- and metaventrites and two visible basal abdominal ventrites with deep round punctures, many of them accumulating fine soil particles; body and all appendages uniformly dark-brown; without dense pilosity; with short and sparse erect setae. Head capsule deeply retracted into pronotum, almost invisible in dorsal view; eye completely absent. Rostrum in lateral view about 0.9 times as long as pronotum in dorsal view; narrowest at mid-length; with deep longitudinal furrow along mid-line dorsally and ventrally; with antennae attached in apical third; with pterygia at points of antennal insertions exposed in dorsal view, scrobes shallow, not visible in dorsal view, directed posteriorly to middle of head. Antennae geniculate, with funicle and club consisting of seven and three antennomeres, respectively; scape about subequal in length to funicle. Prothorax without postocular lobes; procoxae subcontiguous; hypomeral lobes about 60% as long as procoxal cavities; pronotum evenly rounded in dorsal view, without delimited disk, in anterior third with 5–6 fine striae each accommodating 3–5 smaller punctures arranged in longitudinally oriented lines, in posterior half with much larger punctures forming an irregular cross-pattern. Meso- and metathorax with minute scutellum visible externally; hind wings (if present) not examined; mesocoxae separated by about one-third of their individual diameter; metacoxae separated by about their individual diameter. Elytra with humeral angles sharp, slightly produced anteriorly; with eight complete striae, five visible in dorsal view, strial punctures very large in basal one-half of elytral length, decreasing in size in apical portion of length, those on striae 8 very small, shallow throughout length. Abdomen with ventrites I and II subequal in length laterally, densely deeply punctate, III and IV much shorter, combined length shorter than length of ventrite II, impunctate, ventrite V impunctate, about as long as III and IV combined. Legs without femoral teeth; tibial apices with only rows of short, stout spines, spines greatest in number and most closely spaced on front tibia ( Figs. 2G–I ), without tooth-like process potentially homologous to mucro, pre-mucro or uncus; femora without groove in basal half to receive tibiae; tibiae without flat lobes with setal fringes; tarsomere IV present, small and hidden between lobes of tarsomere III ( Figs 2H, I ); claws simple, large, widely divergent. Female genitalia with spiculum ventrale (= internal apodeme of sternum 8) consisting of two weakly sclerotized arcuate basal arms and short, broad, apically expanded apodeme of nearly equilateral triangular shape ( Figs 2K, L ); each gonocoxite (= part of sternum 9, “coxite-stylus”) posteriorly rounded and setose, spade-like, well-sclerotized, lacking stylus

( Figs 2K, L ); sclerotized spermatheca not detected. Male genitalia unknown.

Species composition and distribution. The genus is monotypic and its known distribution is limited to the type locality of its only species (see below).

Etymology. The generic name is a meaningless combination of letters; its gender is masculine.

Note. Males will be expected to have a pedotectal type of genitalia that is typical for Brachycerinae .

Figures

Fig. 2. Yagder serratus gen. & sp. nov., details. A–C – rostral apex, dorsal (A), left lateral (B), ventral (C); D – head, left lateral; E–F – left antenna, lateral (E), distal part magnified (F); G–I – tarsi, left front leg (G–H), left middle leg (I); J – elytral apex; K–L – dissected female abdominal apex, ventral (K) and right latero-ventral (L).