Brachysomus (Hippomias)

Yunakov, Nikolai, 2022, A review of the genus Brachysomus Schoenherr (Coleoptera: Curculionidae: Entiminae), Zootaxa 5193 (1), pp. 1-165 : 20-21

Hippomias : B. kubanensis group

1. Male 5th ventrite emarginate at posterior margin, distinctly depressed in posterior third. Medial margin of hind tibiae straight, in male sharp. Sides of median lobe heavily sclerotized, ventral wall partly membranous. Ventral membranes of aedeagus elongate, moderately sclerotized; endophallus with distinctly U-shaped sclerite, sometimes sclerite divided longitudinally in two halves.......................................................................... B. kubanensis (Reitter)

- Male 5th ventrite with posterior margin not emarginate, posterior third weakly depressed or flat. Medial margin of of hind tibiae moderately sinuate, obtuse. Sides of median lobe weakly sclerotized, ventral wall entirely membranous. Ventral membranes of aedeagus as long as wide, membranous; endophallus without U-shaped sclerite.................................... 2

2. Elytra in male broad-ovate (EL/EW = 1.17–1.32). Erect setae on elytra long (as long as 1/2 interstrial width), narrow, parallelsided, obtuse, arranged in one straight row. Eyes large, strongly convex. Apodemes almost 2x longer than median lobe........................................................................................... B. kovali Yunakov

- Elytra in male ovate or oblong-ovate (EL/EW = 1.36–1.38). Erect setae on elytra short (as long as 1/3 interstrial width), spatulate, apically rounded, arranged in 1–2 confused rows. Eyes small, weakly convex. Apodemes as long as median lobe..................................................................................... B. ellipticus Yunakov

Taxonomy

Genus Brachysomus Schoenherr, 1823

Schoenherr, 1823: 1144. Type species: Curculio hirsutulus Fabricius, 1792 = Curculio echinatus Bonsdorff, 1785

= Pavrosomus Fischer de Waldheim, 1829: 94 .

= Platytarsus Schoenherr, 1840: 919 .

= Thricolepoides O’Brien, 1979: 71 .

Diagnosis. Body length 1.5–4.3 mm, width 1.5–1.7 mm. Vestiture and colour. Body sparsely or densely covered with scales, or almost glabrous. Scales with or without obliterate metallic shine, normally grey to brown. Integument brown to dark-brown; legs and antennae brown, light-brown or yellow. Head: including the eyes not wider than the pronotum at its anterior margin, and without a constriction behind the eyes. Eyes well developed, with 10 or more ommatidia along ELD. Rostrum on average as long as wide. Pterygia only slightly projecting from outline of rostrum. Antennal scrobes lateral, slightly/not visible in dorsal aspect, directed obliquely ventrally, either with well pronounced and parallel dorsal and ventral margins, or with dorsal margin obliterate. Epifrons not separated by transverse sulcus from vertex. Vertex flat, without fovea. Antennae: Scape extending behind posterior margin of eye, does not reach anterior margin of pronotum. 2nd funicular antennomere not longer than 1st. Club compact, antennomeres appearing fused. Legs: Femora edentate. Metatibial apex simple, without proximal fringe and flange ( Thompson 1992). Ventroterminal lobes of 3rd tarsomere not or weakly separated, with well developed bridge between lobes. Claws connate in basal half, divergent in distal half. Thorax: Prothorax with straight anterior margin in lateral view, without prosternal excision and postocular lobes and vibrissae. Hindwings absent. Elytra (longto broad-) ovate to globose, without prominent humeral nor posterior tubercles; elytra with abrupt basal margin. Scutellar shield small, not projecting beyond basal margin of elytra. Abdomen: Posterior margin of ventrite 1 deeply emarginate, that of ventrite 2 straight. Male genitalia: Apex of median lobe acutely or widely rounded, without lateral prominences. Base of endophallus with paired ventral membranes, which are moderately sclerotized, oblong or round or triangular; mesal endopallite absent.

Remarks on systematics. Brachysomus is similar to Foucartia , Amicromias , Eurosphalmus , and Nanomias in general appearance (see Table 1 for a more complete comparison of characters). Eurosphalmus differs from Brachysomus in the shape of the pterygia which are moderately projecting from their lateral contour andin the structure of the aedeagus (ventral membranes large, projecting from preputial field, apical part of median lobe with lateral prominences including the armature of endophallus). Amicromias differs from Brachysomus by the constriction of the head behind the eyes and a depression on the epistome of the rostrum, and by dorsally fully opened and visible antennal scrobes. Foucartia differs from Brachysomus by the body, legs including tarsi, and antennae being more slender, and the antennae relatively longer, by the complete scutellar shield, and by a less steep basal declivity of the elytra. Nanomias differs from Brachysomus by the rostrum significantly shorter than wide, tarsal claws diverging from midlength onward, ventroterminal lobes of 3rd tarsomere separated down to base, antennal scrobes clearly visible in dorsal aspect, posterior margin of abdominal ventrite 1 slightly or not emarginate, that of ventrite 2 rounded.

Subgenus Brachysomus s. str.

Diagnosis. Brachysomus s. str. differs from and Hippomias in presence of intero-basal tooth of mandibular process ( Fig. 10 ); epifrons parallel-sided and at the level of the antennal insertion almost as wide as the vertex between eyes; pterygia slightly project from the contour of the rostrum and in dorsal view are partly covered by the lateral margin of the epifrons ( Fig. 1 ); ventral and dorsal margins of antennal scrobe are both distinct and long ( Fig. 194F ); antennal scape finely punctate, does not extend beyond the anterior margin of the pronotum, generally only reaches the posterior margin of the eye.; tegmen and the dorsal and ventral walls of the aedeagal median lobe are all strongly sclerotised; median lobe anterior to base of endophallus with distinctly modified tip: spear- or stick-shaped protruding, generally acute; paramera distinctly developed; aedeagal apodemes as long as or 1.5x as long as median lobe.

Figures

FIGURE 194. Brachysomus hirtus: A: aedeagus, dorsal view; B: tegmen; C: spermatheca; D: body; E,F: head of male; G: fore tibia of male; H: hind tibia of male; I: fore tarsus; J: scales of elytra; K: setae of elytra.

FIGURES 1–11. Brachysomus. General morphology of the head. 1: B. echinatus, head dorsal view. 2: B. echinatus, head ventral view. 3: B. kubanensis, head ventral view (labium ablated). 4: B. echinatus, head lateral view. 5: B. echinatus, labium: pr—prementum, pm—postmentum. 6, B. echinatus, left mandible, anterior surface 7: B. echinatus, left mandible, posterior surface 8: subgenal angle. 9: B. mihoki, head dorsal view. 10: B. echinatus, left mandible with deciduous process, anterior surface. 10A: B. echinatus, right maxilla anterior surface. 11: B. echinatus, tentorium dorsal view. Abbreviations: af—antennal fossa, bc—buccal cavity, cd—cardo, cly—clypeus, cs—cervical suture, e—eye, ef—epifrons, eld—eye longitudinal diameter, ep—epistome, ga—galea, gat—galeal teeth, gs—gular suture, hls—hypostomal labial suture, hs—hypostoma, la—lacinia, lat—lacinial teeth, mpm1-3—maxillary palpomere 1–3, oco—occipital opening, pac—paracoila (maxillary fossa), paep— paraepistome, pg—palpiger, pm—postmentum, poep—postepistome, poc—postcoila, prc—precoila, ptp—posterior tentorial pits, ptr—prerygium, rl—rostral length, rw—rostrum width, st—stipes. vw—vertex width, php—pharyngeal process, te1— tendon of musculus abductor mandibulae, te2—tendon of musculus adductor mandibulae, tem—temple.

Tables

TABLE 1. Comparison of principal morphological characters between Brachysomus Schoenherr and similar genera. PWa—width of pronotum at anterior margin; HW—width of head including eyes; ibt—intero-basal tooth of mandibular process, N omm /ELD—number of ommatidia fitting in the longitudinal eye diameter.

Character	Rhinomias	Nanomias	Foucartia	Brachysomus	Hippomias	Eurosphalmus	Amicromias
Temple constriction	absent	absent	absent	absent	absent	absent	present
Epistomal carina	absent	absent	present	present	present	absent	absent
Epistome	flat	flat	flat	flat	flat	flat	depressed
HW/PWa	≤1	≤1	>1	≤1	≤1	≤1	≤1
Pterygia	strongly projecting	not projecting	not projecting	slightly projecting	slightly projecting	strongly projecting	slightly projecting
Antennal scrobes	vestigial	vestigial	distinct	distinct	vestigial	vestigial	distinct
N omm /ELD	≥10	≤7	≥10	≥10	≥10	≥10	≥10
Head striation	developed	absent	absent	absent	absent	absent	absent
ibt	absent	absent	absent	present	absent	absent	absent
ventral	not	not	not	not	not	protruding	not
membranes (ligulae)	protruding	protruding	protruding	protruding	protruding		protruding
apical lobes of aedeagus	absent	absent	absent	absent	absent	present	absent
paramera	well developed	vestigial	well developed	well developed	vestigial	vestigial	well developed
Scutellar shield	invisible	invisible	visible	invisible	invisible	invisible	invisible