Khoisan triarthrus Meregalli & Borovec, 2025

Meregalli, Massimo & Borovec, Roman, 2025, Khoisan, a new genus of Cyclominae from South Africa, with nine new species (Coleoptera: Curculionidae), Zootaxa 5646 (1), pp. 1-37 : 10-14

Khoisan triarthrus Meregalli & Borovec sp. nov.

urn:lsid:zoobank.org:act:7AC9B499-F3E4-40DD-AC76-FA4D48F7A12F

Figures 4 , 5

Type locality: South Africa, Northern Cape, S of Soebatsfontein

Material examined: Holotype: ♂, RSA, Northern Cape, Namaqua , S of Soebatsfontein, 280 m, 30°11.754'S, 17°33.275'E [-30.195923° 17.554583°], 13.ix.2013, R. Borovec, M. Meregalli lgt. ( TMSA) . Paratypes: 2 ex., same data as the holotype, ( MMTI, RBSC) ; 1 ♂, RSA, Northern Cape, Namaqua NP, Ca 20 km S Soebatsfontein, 234 m, 30°12.084'S, 17°33.389'E [-30.20140° 17.55649°], 13.xi.2016, sifting of detritus, dead leaves and branches below shrubby Euphorbia, R. Borovec lgt. ( RBSC) ; 3 ex., RSA, Northern Cape, 881 m, Rd from R 382 to Kosies, -29.1167° 17.566871°, 15.xi.2016, Meregalli legit ( RBSC, MMTI) ; 1 ex., RSA, N. Cape, Namaqua , SE of Soebatsfontein, 270 m, -30.16985° 17.61602°, 19.xi.2013 Meregalli lgt. ( MMTI) ; 20 ex., RSA, Northern Cape, Namaqua rd to Hondeklipbaai, nr. Kameelboom , 144 m, 30°28.236'S, 17°41.907'E [-30.4706° 17.69845°], 13.ix.2013, sifting of detritus, dead leaves and branches below shrubby Euphorbia, R. Borovec, M. Meregalli lgt. ( ANIC, NHMUK, MMTI, NMPC, RBSC, SANC) ; 3 ex. RSA, Northern Cape, NE Wallekraal, rd to Kamieskroon , 230 m, 30°20.153'S, 17°36.702'E [-30.33589° 17.61169°] 13.xi.2016, sifting of detritus, dead leaves and branches below shrubby Euphorbia, R. Borovec, M. Meregalli lgt. ( MMTI, RBSC) ; 2 ex. RSA, Northern Cape, 607m, 20 km N Garies , dir. Spoegrivier, -30.340119° 17.798443°, 13.xi.2016, Meregalli legit ( MMTI) ; 2 ex., RSA, Northern Cape, rd. Kliprand- Garies , pass E Rondefonteinsberg, 420 m, 30°44.210'S, 18°14.299'E [-30.73683° 18.23831°], 11.ix.2013, sifting of detritus, dead leaves and branches below shrubby Euphorbia, R. Borovec, M. Meregalli lgt. ( RBSC) ; 1 ex., RSA, Western Cape, R 358 NE Bitterfontein, 397 m, 30°53.921'S, 18°19.809'E [-30.89868° 18.33015°], 21.xi.2016, sifting of detritus, dead leaves and branches below shrubby Euphorbia, R. Borovec, M. Meregalli lgt. ( RBSC) ; 7 ex., RSA, Western Cape, SW Nuwerus, 356 m, 31°11.266'S, 18°20.286'E [-31.18777° 18.33810°], 12.xi.2016, sifting Euphorbia, R. Borovec lgt. ( MMTI, RBSC) ; 5 ex., RSA, Western Cape, 1 km SE Vanrhynsdorp , 117 m, 31°37.234'S, 18°43.681'E [-31.62057° 18.72802°], 10.ix.2013, sifting of detritus, dead leaves and branches below shrubby Euphorbia, R. Borovec, M. Meregalli lgt. ( RBSC, MMTI) ; 7 ex. RSA, Western Cape, 240 m, Rd N 7 N Vanrhynsdorp to Flamintvlakte, 10.ix.2013, -31.21229° 18.55899°, sifting karoo, Meregalli lgt. ( MMTI, RBSC) ; 1 ex., RSA, Western Cape, Ca 35 km S Vanrhynsdorp, 3 km S Trawal rd N7, 65 m, 31°54.881'S, 18°31.658'E [-31.91469° 18.52762°], 9.xi.2013, sifting of detritus, dead leaves and branches below shrubby Euphorbia, R. Borovec, M. Meregalli lgt. ( RBSC) .

Description. Body length 1.72–2.53 mm, holotype 2.23 mm. Body dark brownish to black; antennae and tarsi yellowish red; apical half of rostrum pale reddish brown, in females usually darker. Scales of various colours, ochre, brown to black and white, on smooth part of integument broad, often apically bifid, scarcely erect, on tubercles longer, concave, C-shaped, some pedunculate, usually black or dark brown on dorsum of pronotum and elytra, white on sides and declivity, on sides irregularly disposed, not aligned along interstriae, rather regularly spaced, tubercles on dorsum of pronotum and elytra with ochre or black scales, on sides with white to translucent scales, usually pedunculate; setae brown, slender, spatulate, inserted on top of tubercles, few on rostrum and few on legs.

Rostrum in males 2.9–3.2× as long as wide at base, in females 3–3.4× as long as wide; in lateral view in males 0.9–1.2× as long as pronotum, in females 1–1.2× as long as pronotum. Basal half of rostrum in dorsal view in males irregularly tapered apicad with slightly curved sides, in females evenly tapered apicad with straight sides; apical half of rostrum in both sexes with slightly concave sides; rostrum in both sexes at base 1.48–1.65× as wide as at apex. Antennal insertions between middle and apical third of rostrum.

Scapes 2.1–2.3× as long as funicle, at apex 0.8–0.9× as wide as club; funicles 3-segmented, segment 1 globose to conical to cylindrical, 1.4–2.6× as long as wide and 1.5–2.2× as long as segment 2, this 1.4–1.5× as long as wide; segment 3 as long as wide to slightly transverse; clubs elongate, 2.1–2.3× as long as wide.

Pronotum 0.92–1.05× as long as wide, in anterior quarter sharply compressed, dorsum with four tubercles, two in median part, two placed towards base, anterior margin slightly curved, lacking prominent humps; sides with two tubercles, one at anterior third, one at midlength, sides sublinearly convergent towards base, or slightly curved; base slightly curved.

Elytra short, in males 1.05–1.2× as long as wide, in females 1.15–1.25× as long as wide; striae with very narrow, barely distinct punctures, narrower than width of interstriae; interstriae 2 with tubercle before declivity; interstriae 3 with oblong tubercle at base, a conical tubercle before declivity and another one on declivity, interstriae 5 with two tubercles, interstriae 7 with four high conical tubercles; females usually with basal tubercle on interstriae 7 strongly prominent, and elytra subtriangular, with maximum width behind humeri.

Legs short, protibiae robust, 3.8× as long as wide, not broadened apicad, with narrow granule before midlength and before apex.

Penis in dorsal view 2.3–2.5× as long as wide, widest at basal half, in apical half evenly tapered apicad with rounded sides, tip slightly extended anteriorly; in lateral view regularly curved, evenly tapered apicad. Endophallus with two short parallel sclerites.

Spermatheca with cornu slender and regularly curved; corpus rounded; ramus almost indistinct, extremely short, hump-shaped; collum tube-shaped, distinctly curved, directed forward.

Bionomics. All specimens were collected by sifting litter under large Euphorbia shrubs and found together with different genera and species of entimines and various other genera of Cyclominae ( Fig. 6 ).

Variation. This species shows strong morphological variation, partly between the sexes, partly within a population and partly between locations. Females often have slightly longer elytra and higher tubercles. The greatest variation regards the shape of the elytra, which may be more rounded or subglobose, the height of the tubercles and the colour and shape of the scales, which may be oval, C-shaped, ochre-coloured, non-pedunculate even on the tubercles, or brownish to black, pedunculate even on the flat parts of the elytra. The specimens from the northernmost locality, near Kosies ( Figs 3a, b ), are rather similar to those from south of Soebatsfontein, with relatively low tubercles and ochreous scales on tubercles, whereas those from Kameelboom ( Figs 3a,b ) have darker scales, the erect pedunculate scales more frequent and ochreous scales absent, the tubercles taller, particularly the subhumeral ones, which are rather prominent outwards, and the elytra subtriangular in shape; these are the specimens most different from those from south of Soebatsfontein. Those from Nuwerus and Bitterfontein ( Figs 3g,h ) are relatively similar, but the tubercles are shorter, whereas those from Kliprand ( Figs 3e,f ) are similar to those from south of Soebatsfontein. The specimens from the vicinity of Flamintvlakte ( Figs 3k,l ) have long, ochreous, raised pedunculate scales and smaller tubercles; those from the outskirts of Vanrhynsdorp are similar, but the scales are shorter and the scales on the sides smaller, almost appressed to the integument. The southernmost population, near Trawal ( Figs 3i,j ), does not show any particular difference from those further north. The penis does not show any differences between the populations.

Derivation of the name. The name, meaning with three segments, refers to the 3-segmented antennal funicles of this species, a condition only occurring in this genus among the known Cyclominae . The name is to be treated as a noun in apposition.

Distribution. This species has a relatively wide range, stretching from north of Steinkopf in the Northern Cape to south of Vanrhynsdorp in the northern part of Western Cape, along a narrow strip a short distance from the coast. The northernmost locality, near Kosies, is more than 100 km from the next one to the south, but this gap is probably due to a lack of data from intermediate localities ( Figure 8 ).

Remarks. Khoisan triarthrus shares the character of the 3-segmented funicles with K. albogibbosus , which differs in having the rostrum black, the elytral striae with round large punctures (wider than the interstriae), the dorsal pronotal and elytral tubercles round, with short white scales appressed to integument on their upper part, and the tibiae with thick scales.

Figures

FIGURE 3. Bayesian Inference consensus tree, all branches are shown. Branch post probability support is indicated on the branches, in percentage. Scale bar unit: expected substitutions per site.

FIGURE 4. Khoisan triarthrus. Body, dorsum (a), side (d); head with rostrum, dorsal view (h), lateral view (j); antenna (i); pronotum, dorsal view (f), lateral view (e); elytra, dorsolateral view (b), dorsal view (g); protibia (c); ventrites (k); penis, ventral view (1), profile (m). Scale bar 1 mm; figures not to scale.

FIGURE 5. Body, dorsal and lateral view of Khoisan triarthrus: Kosies (a, b); Kameelboom (c, d); Kliprand (e,f); Bitterfontein (g, h); Trawal (i,j); Flamintvlakte (k, 1).

FIGURE 6. Habitat of Khoisan triarthrus, Namaqua National Park, south of Soebatsfontein.

FIGURE 8. Distribution map. Symbols with a black dot indicate the locality of the holotype. Map generated from https://www. openstreetmap.org.