Kostalius Borovec, 2025

Kostalius Borovec , gen. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act:EA0DC52A-B9FB-4A3E-BA3D-2144F09D4983

Figs (8–12, 44–57)

Type species. Kostalius rotundisetis Borovec , sp. nov. by present designation. Gender masculine.

Diagnosis. Small, edaphic, wingless Oosomini , body length 1.9–3.3 mm. Sparse, perpendicularly erect piliform setae on dorsal part of body isolated, not covering integument; rostrum distinctly wider than long; epifrons wide, at base as wide as distance between inner margins of eyes; frons very short, glabrous; mandibles trisetose; scrobes in lateral view directed towards eye; eyes small, placed in middle of head; subgena in middle glabrous; scapes abruptly enlarged, at apex distinctly wider than clubs; pronotum with transverse incision in the entire width; procoxal cavities narrowly separated; mesoventral process as wide as a half of mesocoxa diameter; abdominal ventrite 1 as long as ventrites 2–4 combined, all sutures straight; protibiae apically fringed with setae; meso- and metatibiae with glabrous apical surface and unobtrusive mucro; metatibiae lacking corbels; claws free; female sternite VIII with long and slender apodeme terminating at base of small plate; gonocoxites slender with apical styli.

Description. Body length 1.9–3.3 mm. Integument of body ( Figs 8–12 View FIGURES 5–8 View FIGURES 9–12 ), antennae and legs brown reddish with sometimes funicles with clubs and tarsi paler, yellowish, or clubs blackish. Dorsal part of body in clean specimens sparsely covered by perpendicularly erect short piliform setae, apically shortly curved, not covering integument, 3 across width of one interstria. Elytral interstriae 1, 3, 5 and 7 with sparse row of subspatulate to rounded erect scales; pronotum with identical scales as those on elytra, forming transverse rows; head with rostrum with rows of smaller semi-erect setae mainly on epifrons margins. Antennal scapes with short, piliform appressed setae and row of erect, subspatulate to rounded scales on inner sides; funicles with short, semi-erect, pale, inconspicuous setae; clubs finely densely setose in apical half. Femora with semi-appressed, narrow setae; tibiae with short, fine, piliform setae and row of erect subspatulate to rounded scales on outer margin; tarsi sparsely setose. The entire ventral part of body including coxae densely covered with small, oval, appressed scales; gena glabrous; subgena laterally densely squamose with oval appressed scales, in middle from base to apex glabrous.

Rostrum ( Figs 44–47 View FIGURES 44–57 ) short and wide, 1.4–1.6× as wide as long, subparallel-sided to widened apicad; in lateral view with dorsal margin distinctly vaulted, ventral margin slightly shorter than thickness of rostrum at its base. Epifrons wide, occupying majority of rostral width, widest at base and here as wide as distance between inner margins of eyes, distinctly tapering apicad with straight sides, posteriorly separated from head by shallow transverse furrow with ill-defined margins, before or behind eyes. Frons very short, forming short glabrous stripe around epistome, with 5 pairs of long fine setae. Epistome short, arched, posteriorly carinated. Mandibles small, glabrous, trisetose. Antennal scrobes in dorsal view visible only at place of antennal insertions or as narrow furrows; in lateral view short or slender, furrow-shaped, directed towards eye, reaching it or separated from it by slender squamose stripe. Eyes small, laterally placed, invisible or slightly visible in dorsal view; in lateral view subcircular, placed in middle of head or slightly below. Vertex wide, regularly domed, with small fovea in middle, hidden by vestiture; head short, distinctly enlarging posteriad; head and rostrum under vestiture and encrustation smooth with sparse, fine punctures.

Antennae ( Figs 9–12 View FIGURES 9–12 ) with short and robust scape and slender funicle; scape at basal quarter very slender, then abruptly enlarged, in apical three quarters wide, almost parallel-sided, here 3–4× as wide as at base, slightly curved and 1.4–1.7× wider than clubs, reaching behind posterior margin of eyes in repose; funicle with 6 or 7 articles, articles 1 and 2 long, conical, the others short, isodiametric to wider than long; clubs short, article 1 largest, comprising half of club length, sparsely setose.

Pronotum ( Figs 9–12 View FIGURES 9–12 ) 1.5–1.7× as wide as long, widest at midlength, in anterior half narrower than in posterior half, behind anterior margin constricted with anterior margin distinctly narrower than posterior margin; base straight; disc distinctly domed with irregular small tufts of setae or small bumps; disc in anterior third with distinct transverse incision in the entire width, often hidden under vestiture and encrustation, in very clean specimens disc smooth with very sparse and fine punctures; anterolateral margin straight, directed distinctly obliquely ventrad to procoxae, without vibrissae or ocular lobes. Procoxal cavities ( Fig. 8 View FIGURES 5–8 ) round, located in middle of very short ventral part, equally very near to anterior as well as posterior margin, narrowly separated, space between them about a quarter to fifth of procoxal diameter; procoxae subglobular; anterior margin in ventral part distinctly arched. Scutellar shield not visible.

Elytra ( Figs 9–12 View FIGURES 9–12 ) globular to oval, 1.1–1.2× as long as wide, with regularly rounded sides, apically broadly rounded, lacking laterally prominent humeral calli or subhumeral bumps; 10-striate; base straight, as wide as base of pronotum. In very clean specimens the integument is smooth, striae distinctly punctured, as wide as interstriae. Elytra with posterior declivity overhanging apex, this is thus not visible dorsally. Mesocoxae globular; mesoventral process moderately wide, about as wide as a half of mesocoxa diameter. Metacoxae round, metaventral process narrow ( Fig. 8 View FIGURES 5–8 ). Mesanepisterna large, densely squamose; mesepimera small, narrow, subtriangular, hardly visible; metanepisterna lacking. Wingless.

Abdominal ventrites ( Fig. 49 View FIGURES 44–57 ) 1.1–1.2× as long as wide, subtriangular, moderately small, because lateral margins of elytra reaching far inside in ventral side of body; ventrite 1 at middle slightly shorter than ventrites 2–4 combined, behind metacoxa somewhat longer than ventrite 2; ventrite 2 slightly shorter than ventrites 3 and 4 combined; ventrite 5 subtrapezoidal, slightly longer in females than in males. All sutures straight; suture between ventrites 1 and 2 fine and narrow, the others wide and rough. Metaventral process narrow, slightly narrower than transverse diameter of metacoxa. Ventrites densely squamose.

Femora medially inflated, unarmed; tibiae moderately slender; protibiae ( Fig. 48 View FIGURES 44–57 ) with mesal and lateral margin straight, apically obliquely subtruncated, fringed by fine, dense, brownish or blackish setae, with unobtrusive brown mucro. Meso- and metatibiae with apical surface glabrous and brown unobtrusive mucro. Tarsi short; tarsomere 1 shorter than 2 and 3 combined; tarsomere 2 very short; tarsomere 3 distinctly wider than the others; onychium slightly shorter than tarsomere 3. Claws free, divaricate.

Male terminalia. Penis ( Figs 50, 51 View FIGURES 44–57 ) slender and moderately long, temones almost twice longer than body of penis; endophallus inside with irregularly shaped 1–2 sclerites. Tegmen ( Fig. 52 View FIGURES 44–57 ) with slender, complete ring, in one species with short translucent parameres, in second lacking parameres; manubrium about twice as long as diameter of ring. Sternite IX with spiculum gastrale moderately long, anteriorly curved, in one species forming plate, posteriorly with fused basal arms.

Female genitalia. Sternite VIII ( Figs 55, 56 View FIGURES 44–57 ) with long, slender apodeme, 3.3–4.6× as long as plate, terminating as short basal margins of plate; plate small, subtriangular or oval, with slender apical margin fringed by short, fine setae. Gonocoxites ( Fig. 57 View FIGURES 44–57 ) very slender, tube-shaped or narrowly subtriangular, with long and slender apical styli with fine setae. Spermatheca ( Figs 53, 54 View FIGURES 44–57 ) with short cornu; ramus and collum developed, differing between the species.

Sexual dimorphism. The sexes are externally indistinguishable except for slight differences in the shape of ventrite 5.

Derivation of name. The newly described genus is dedicated to my age-long friend and colleague, with whom we started to study weevils as students, Dr. Michael Košťál (Šoporňa, Slovakia), an eminent specialist in several different groups of Curculionidae . He is also a collector of both Kostalius species.

Biology. All type material was sifted in two different habitats: K. sylvaticus was sifted in indigenous forest from forest litter, and K. rotundisetis was sifted in an open landscape, from litter under Ericaceae bushes.

Distribution. Species of the genus are known only from six localities in South Africa, Eastern Cape.

Species included. The genus includes two here described species.

Taxonomic remarks. Although both species look slightly different, which is most likely caused by their different kind of life in different type of habitats, both species share many characters assumed to be important at the generic level: rostrum distinctly wider than long, very short glabrous frons, developed epistome, scrobes in lateral view directed towards middle of eye, eyes small, placed in middle of head height, mesoventral process as wide as half width of mesocoxa diameter, all tibiae with unobtrusive mucro, meso- and metatibiae with glabrous apical surface, abdominal ventrites squamose with narrow metaventral process, ventrite 1 as long as 2–4 combined, all sutures straight, claws free, female sternite VIII with long, slender apodeme, terminating as short basal margins of small plate. But the main synapomorphy of both species is a very short ventral part of the pronotum with narrowly separated procoxal cavities, which is a character not known to me among all Afrotropical entimines. To my knowledge, all other genera of Entimines in southern Africa (about 110 genera) have procoxal cavities contiguous. Separated procoxal cavities very easily differentiates this genus from all other genera of South African entimines.

The newly described genus belongs to the tribe Oosomini by having free claws, trisetose mandibles, dorsally placed scrobes, rostrum separated from the head by a shallow transverse sulcus, a lack of ocular lobes or vibrissae on pronotal lateral margins, a lack of protruding humeral calli, and a lack of metatibial corbels. In its small body size, short and robust extremities, and reduced eye size, it is similar to other genera with an edaphic way of life.

Kostalius can be distinguished from them by the following key:

1. All femora with tooth. Ventral margin of rostrum in lateral view as long as thickness of rostrum at its base. Slope of elytral declivity hardly overhanging apices of elytra in dorsal view. Female sternite VIII with apodeme subequal in length with large plate. Rostrum posteriorly continuous with head. Body size 2.3–3.0 mm. Lesotho............... Basothorhynchus Borovec View in CoL

- All femora edentate. Ventral margin of rostrum in lateral view shorter than thickness of rostrum at its base. Slope of elytral declivity distinctly overhanging apices of elytra in dorsal view. Female sternite VIII with apodeme distinctly longer than small plate. Rostrum posteriorly continuous with head or separated by transverse furrow.................................. 2

2. Eyes large, positioned subdorsally. Frons and apical part of epifrons glabrous. Rostrum distinctly tapering anteriad, posteriorly continuous with head. Epifrons at base reaching middle of anterior margin of eyes. Scrobes in lateral view distinctly enlarging posteriad with ventral margin directed deeply below ventral margin of eye. Abdominal ventrite 1 longer than ventrites 2–4 combined. Body size 1.3–1.8 mm. Eastern Cape ...................................... Dimorphophthalmus Borovec View in CoL

- Eyes small, laterally placed. Frons very short, glabrous, epifrons densely squamose. Rostrum parallel-sided or apically enlarged, posteriorly separated from head by shallow transverse furrow. Epifrons at base at most as wide as distance between inner margins of eyes. Scrobes in lateral view furrow-shaped with ventral margin directed towards ventral margin of eye. Abdominal ventrite 1 as long as ventrites 2–4 combined................................................................ 3

3. Epifrons at base narrower than space between anterior margins of eyes. Scapes evenly enlarging apicad, at apex slightly narrower than clubs. Procoxal cavities contiguous. Disc of pronotum lacking transverse incision. Female sternite VIII with apodeme terminating inside of umbrella-shaped plate with membranous basal margin. Appressed oval scales on elytra densely covering integument. Body size 1.8–3.2 mm. Western Cape ............................ Bulirschius Borovec , gen. nov.

- Epifrons at base as wide as distance between inner margins of eyes. Scapes abruptly enlarging apicad, at apex wider than clubs. Procoxal cavities narrowly separated. Disc of pronotum with transverse incision. Female sternite VIII with long apodeme terminating at base of oval to subtriangular plate with visible basal margin. Sparse piliform erect setae on elytra not covering integument. Body size 1.9–3.3 mm. Eastern Cape. …................................... Kostalius Borovec , gen. nov.