Khoisan 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 : 3-10

publication ID	https://doi.org/10.11646/zootaxa.5646.1.1
publication LSID	lsid:zoobank.org:pub:3699C7A0-AFCA-4F24-B676-F5F2E9C90B20
DOI	https://doi.org/10.5281/zenodo.15850560
persistent identifier	https://treatment.plazi.org/id/057E87A4-FFC5-FF5B-FF6D-F89684694C32
treatment provided by	Plazi
scientific name	Khoisan Meregalli & Borovec
status	gen. nov.

Treatment

Khoisan Meregalli & Borovec , gen. n.

urn:lsid:zoobank.org:act:278BA3B3-B1DF-45A6-8326-64F52C25F3EA

Figure 1 View FIGURE 1

Type species, by present designation: Khoisan triarthrus Meregalli & Borovec sp. nov.

Gender: masculine.

Diagnosis. Small Cyclominae , less than 2.8 mm long; head bent downwards from longitudinal line of body ( Fig. 1g View FIGURE 1 ), rostrum narrow and long, in dorsal view with basal half densely scaled, scales forming lateral strip extended out of lateral margins before antennal insertion, apical half glabrous ( Fig 1h View FIGURE 1 ), in ventral view glabrous along entire length, excepting basal lateral strip of scales ( Fig. 1d View FIGURE 1 ); underside with a transverse row of spaced small setae ( Fig. 1o View FIGURE 1 ); antennae inserted at midlength or between midlength and anterior third of rostrum; rostrum in lateral view moderately curved, usually more curved at midlength ( Fig. 1l View FIGURE 1 ); scrobes very short, directed towards underside; funicle with 3–5 segments, club with basal segment longer than 2 apical segments combined ( Fig. 1f View FIGURE 1 ); pronotum and elytra tuberculate ( Fig. 1b View FIGURE 1 ); pronotum anteriorly prominent above head ( Fig. 1p View FIGURE 1 ); prosternum deeply excavate to receive rostrum in repose ( Fig. 1c View FIGURE 1 ); tibiae short, without distinct mucro, with a row of subapical spines and 2 spurs ( Fig. 1m View FIGURE 1 ); tarsi with small moniliform segments, segment 3 similar to 2, not lobed ( Fig. 1i View FIGURE 1 ); gonocoxites apically membranous, lacking styli, with fine sparsely scattered setae ( Fig. 1n View FIGURE 1 ); sternite VIII of female with umbrella-shaped plate, translucent, with sclerotized strip along apical margin ( Fig. 1j View FIGURE 1 ). Body incrusted, possibly covered by exudate to which soil particles adhere ( Fig. 1a View FIGURE 1 ).

Description. Body length 1.7–2.75 mm. Body integument pale to dark brownish or blackish, antennae black or funicles with club reddish or yellowish brown; tarsi pale reddish, brown or black. Vestiture consisting of scales of various shape, appressed to integument or suberect or erect, white, yellow, ochreous, brown or black, spatulate, or longitudinally concave, C-shaped in section, often with deep indentation, longer scales often long pedunculate, present on dorsal and ventral part of body, protruding outwards on sides of rostrum, usually reciprocally isolated and not touching one another on unsculptured parts of integument, seldom partially imbricate, thickened or very compact on rostrum, tubercles and humps, apex of elytral tubercles in some species with a tuft of fan-shaped scales; apical and ventral part of rostrum, ventral head capsule, antennal funicles and clubs and tarsi lacking scales; scapes with inconspicuous small appressed scales on anterior side ( Figs. 1t –w View FIGURE 1 ). Dorsal and ventral part of body and legs with sparse narrow long erect setae, mostly inserted on top of tubercles or granules on tibiae, usually dark-coloured; apical glabrous part of rostrum with sparse, short, semi-erect hair-like setae, dorsally, laterally as well as ventrally prominent; antennae and legs with sparse, unevenly scattered, short, hair-like semi-erect setae. Entire body usually incrusted with soil, obscuring scales and details of sculpture ( Fig. 1a View FIGURE 1 ). Integument sculpture when cleaned from soil rugose or smooth, pronotum and elytra with large raised tubercles ( Fig. 1b View FIGURE 1 ). Rostrum long, narrow, almost circular in cross section, almost of same width from base to apex if basal strip of scales protruding outside of lateral margin is excluded from measurement, in males 2.4–3× as long as wide, in female 2.7–3.2× as long as wide (width at base measured including lateral strip of scales); in dorsal view widest at base, here, including external strip of scales, 1.3–1.8× as wide as at apex, in basal half often slightly tapered apicad, with straight or slightly curved sides; rostrum in apical half narrower, usually feebly enlarged apicad, with slightly concave sides, beyond antennal insertions glabrous, unpunctate, smooth to finely shagreened; in middle in some species at place of antennal insertions with slightly curved sides, before and behind slightly constricted. Rostrum in ventral view subparallel-sided along entire length, glabrous, smooth, with raised keel from antennal insertions to underside of head, in basal half distinctly laterally framed by protruding scales; in lateral view in males 0.8–1.1×, in females 1–1.3× as long as pronotum, slightly curved, widest at base, in basal half slightly evenly tapered apicad, in apical half subparallel-sided or tapered. Rostrum posteriorly not dorsally separated from head. Frons and epistome indistinct. Mandibles very small, lacking scales, without mandibular scars.Antennae inserted between middle and apical third; antennal insertions not visible in dorsal view, placed on side of rostrum ( Fig. 1h View FIGURE 1 ), scrobes very short, directed towards underside, in lateral view visible only shortly behind insertion ( Fig. 1l View FIGURE 1 ). Head round, short and broad, insertion curved downwards from longitudinal line of body, underside with transverse row of narrow setae below eyes and through entire underside from side to side, in lateral view flat or distinctly concave. Eyes small, in dorsal view almost flat, in lateral view placed in middle of head.

Antennae short; scapes in repose not reaching eyes, 3.7–6.4× as long as wide at apex, 1.5–2× as long as funicle, in short basal part slightly curved, then straight, slightly evenly enlarged apically, at apex 0.6–1× as wide as club. Funicles with 3, 4 or 5 segments, segment 1 longest. Antennal clubs oval to long spindle-shaped, basal segment at least half as long as club length, in species with 3-segmented funicles with incomplete rows of setae in places of previous sutures after fusion of terminal funicle segments.

Pronotum broadly subquadrate to subtrapezoidal, distinctly narrower than elytra, 0.90–1.20× as long as wide, widest before midlength, seldom at midlength, more or less tapered posteriorly with straight sides, distinctly constricted at about anterior third ( Fig. 1p View FIGURE 1 ). Disc indistinctly flatly granulate or sparsely punctate, with two–four tubercles on dorsum, two at middle and two near base, sides with tubercle before anterior constriction, often another tubercle behind, towards base, and smaller one in lower part, in intermediate position between others; anterior margin in dorsal view swollen, anteriorly hood-shaped, extended above head, in some species with two–four small tubercles prominent anteriorly; base straight to slightly arched, in lateral view with well-developed postocular lobe, lacking vibrissae in dorsal portion. Procoxal cavities contiguous, round; procoxae subglobular, placed at base of prosternum, very distant from anterior margin; anterior margin ventrally deeply arched. Prosternum deeply excavate to receive rostrum in repose. Scutellar shield indistinct.

Elytra shortly oval, 1.0–1.2× as long as wide, 10-striate, integument smooth or slightly rough, striae very small, or with round deeply impressed punctures, as wide as or wider than width of interstriae, usually curved around tubercles; interstriae 2 with tubercle at beginning of declivity, interstriae 3 with two–three tubercles, often with one at base, and in some species with small apical tubercle, interstriae 5 with two-three tubercles, interstriae 7 usually with four, equally spaced prominent tubercles; shoulders obliquely subtruncate posteriorly ( Figs 1b,g View FIGURE 1 ). Apices of elytra visible in dorsal view. Metathoracic wings absent. Mesocoxal cavities circular, narrowly separate, mesoventral process narrow. Metacoxae slightly transverse, laterally not reaching elytral margins, separated by about their width ( Fig. 1c View FIGURE 1 ). Legs short and robust. Femora unarmed, inflated at middle. Tibiae short and robust, straight, with straight internal side, occasionally external side expanded outwards near apex, with granule, apices not expanded mesally or laterally, broadly transversely truncate, with several sparse, short, unobtrusive black bristles or few dark subapical spines and two tiny spurs; mucro indistinct; protibiae 2.3–3.5× as long as wide at apex. Tarsi with first three segments bead-shaped, subequal in length and width, segment 3 not bilobed, onychium longer than segments 2 + 3 together, evenly enlarged apically, at apex slightly wider than others; in some species protarsi shorter than meso- and metatarsi. Claws free, moderately long, distinctly divergent ( Fig. 1i View FIGURE 1 ).

Ventrites 1.1–1.3× as long as wide, smooth, ventrite 1 at midwidth 1.5× as long as 2 and about as long as ventrites 3 and 4 combined, ventrite 5 in males shorter, subtrapezoidal, in females longer, apically rounded. Suture between ventrites 1 and 2 straight or slightly sinuate at middle, fine, other sutures straight, rough. Metaventral process obtuse, about as wide as transverse diameter of metacoxa ( Fig. 1k View FIGURE 1 ).

Male terminalia. Penis moderately short, slightly shorter than or as long as temones, differing in shape between species; endophallus with sclerites short or small, stick-shaped or rounded ( Fig. 1q View FIGURE 1 ). Tegmen with manubrium about twice as long as diameter of slender ring, lacking parameres ( Fig. 1r View FIGURE 1 ). Sternite IX slightly curved, anteriorly enlarged to small, wide, rounded plate; basal arms fused posteriorly ( Fig. 1e View FIGURE 1 ).

Female terminalia. Gonocoxites simple, inconspicuous, weakly sclerotized, slender, elongate, slightly curved outside, evenly tapered apically; short apical portion membranous, narrowly rounded, lacking styli, with short and fine, sparsely scattered setae ( Fig. 1n View FIGURE 1 ). Sternite VIII with moderately long and slender apodeme, Y-shaped, terminating in apical portion of plate; plate umbrella-shaped, in middle portion membranous, translucent, about one quarter of apodeme length; apical margin in short median part interrupted, slender, bearing sparse short setae, with more sclerotized strip along entire length, gradually narrowed, exceptionally connected at middle or connected with Y- shaped termination of apodeme; basal margin membranous ( Fig. 1n View FIGURE 1 ). Spermatheca with regularly curved, slender tapered cornu, rounded corpus, very short, indistinct ramus and short, tube-shaped collum ( Fig. 1s View FIGURE 1 ).

Sexual dimorphism. The rostrum in some species is longer and thinner in females than in males. Ventrite 5 is longer and apically rounded in females, shorter and subtrapezoidal in males. In one species the apical half of the rostrum is reddish-brown in males and darker in females; in one species females have more prominent elytral tubercles, particularly the humeral one, so that the elytra are broader at the base and subtriangular, with the sides sublinearly narrowed apicad, whereas males have shorter tubercles and more regularly oval elytra.

Individual variation. Intraspecific variation mainly concerns size, height of the tubercles and density and colour of the scales. In one species, K. triarthrus sp. nov., the variation in the elytral sculpture and shape and in the form of the scales is conspicuous.

Derivation of the name. The genus name is derived from the indigenous people of southern Africa, living between the Cape region and Namibia, the same region where the new genus occurs. The name Khoisan , or Khoe-Sān, is a catch-all term for those people that do not speak one of the Bantu languages, combining the Khoekhoen (formerly “Hottentots”) and the Sān (formerly “Bushman”) ( Wikipedia 2025).

Distribution. South Africa, native to the Northern and Western Cape, southern and eastern part of the Eastern Cape, near the border with the Free State, where it may be present ( Figures 8 View FIGURE 8 , 18 View FIGURE 18 ).

Taxonomic placement

The placement of the new genus was not immediately apparent because of its strong peculiarities. The pedal-type of the aedeagus excludes Khoisan from the basal subfamilies of Curculionidae , such as Brachycerinae, but it was not easy to determine its proper classification, not the least because of the still incomplete definition of the typical characters of the curculionid subfamilies and their unclear delimitations, as evidenced also by several inconsistences between the traditional classification and the results of recent molecular studies (e.g., Haran et al. 2023b). At first, we were uncertain whether Khoisan could belong to Curculioninae, Molytinae or Cyclominae . The first subfamily, which might have been considered because of its cylindrical rostrum, was readily ruled out due to the presence of distinct ocular lobes, the anterior margin of the pronotum expanded above the head, the broad pro- and mesocoxal cavities, the strongly tuberculate, thickly incrusted body and the moniliform tarsi, with segment 3 identical to segment 2, not bilobed. The choice between Molytinae and Cyclominae was more difficult to make, essentially because of the general appearance of the body, with high tubercles on the pronotum and elytra and the pronotum expanded anteriorly. However, the differences in the shape of the female sternum VIII and the gonocoxites, the absence of a clear uncus on the tibiae, the possession of tibial spurs and the moniliform tarsi suggested its placement in Cyclominae , the group in which Marshall had also placed an undetermined specimen preserved at the NHMUK. Affinities of the new genus among the Cyclominae have not been established with a sufficient degree of confidence, although the tuberculate body, the moniliform tarsi, the shape of the pronotum are reminiscent of species of Rhythirrinini and Hipporhinini. Both tribes differ in their shorter rostrum and strongly sclerotised gonocoxites, usually with a developed distal process. The subfamily was revised by Oberprieler (2010), who based his approach mainly on the structure of the ovipositor and listed the main morphological characters distinguishing the tribes.

We found some similarities between Khoisan , Pachytrichus Schoenherr, 1836 , and Terapopus Schoenher, 1845 ( Figure 2 View FIGURE 2 ).

Pachytrichus , formerly in Rhythirrinini, was excluded from the tribe and placed in Curculioninae incertae sedis, possibly sharing relationships with Hypsomus ( Oberprieler 2010) . It shares with Khoisan various features of the rostrum, in particular the laterally protruding strip of scales at the base, which is not seen in any other genus; the rostrum, viewed from below, is also similar, but the raised keel present in Khoisan is very short and scarcely raised; dorsally and laterally it has a similar appearance, except for a much shorter extension beyond the antennal insertions, so that antennae are subapical. The scales on the meso- and metarostrum and the pronotum are erect, concave in section, with thickened margins. Pachytrichus differs from Khoisan in having slender, normally shaped antennae, with 6-segmented funicles, the surface of the pronotum and elytra is smooth, without tubercles, the entire body is covered with long setae and the size is bigger, about 5 mm. The most important differences are the apically slightly dentate gonocoxites (Oberprieler, personal communication), the strong mucro at the apex of the tibiae and the broadly bilobed segment 3 of the tarsi.

Terapopus is a genus currently classified in Rhythirrinini. Its general appearance indeed matches that of species of the tribe. It shares with Khoisan the elytra with tubercles on the interstriae 3, 5, 7 and the pronotum with broad ocular lobes, prominent above the head. It differs in having a short and broader rostrum, not extended before the antennal insertions, lacking a protruding strip of scales, the scrobes laterally visible along the entire length, the gonocoxites with a long spatulate distal process, the tibiae with a small but distinct mucro and the tarsi slightly broadened, not moniliform. The antennae are slender, with 7-segmented funicles and the size is larger, up to 4 mm.

Thus, neither genus appears to be related to Khoisan . The rostrum of Pachytrichus shows surprising similarities, but the broadly bilobed tarsi and the large mucro are taxonomically significant features that led us to exclude any relationships between the two genera.

In Bayesian Inference of the COI sequence a specimen of Khoisan mendeli sp. nov. clustered in the CEGH clade (sensu Haran et al., 2023b), and, within this clade, among the taxa forming the core group that appears to constitute a monophylum corresponding to the true Cyclominae ( Baird et al. 2021; Haran et al. 2023b). We are aware of the impossibility of reconstructing reliable phylogenetic relationships using only a single mitochondrial gene fragment, but the inclusion of Khoisan in the CEGH clade, together with genera belonging to the core Cyclominae clade ( Figure 3 View FIGURE 3 ), supports our conclusions based on the morphological analysis. It was placed as sister to Steriphus (currently in Listroderini, Oberprieler 2010), but such a placement is not supported morphologically. No affinities were observed with Hypsomus , which fell into a distinct clade, and no particular affinity was observed with Rhythirrinini, in spite of its general resemblance.

Therefore, considering also that Rhythirrinini were defined as “the most confused tribe of Cyclominae , the latest checklist ( Alonso-Zarazaga & Lyal 1999) reflecting an amalgam of unrelated genera” ( Oberprieler 2010), we prefer to avoid adding further heterogeneity to the circumscription of the tribe and prefer to leave Khoisan as Cyclominae incertae sedis.

Along with the distinctive shape of the rostrum and its sexual dimorphism, one of the most striking features of the new genus is the reduction of the funicle segments, down to the extreme of only 3 segments in two species. If taxa with 6-segmented funicles are quite frequent in the family, further reduction becomes progressively more uncommon, and 3-segmented funicles occur only in taxa outside the CEGH clade. In Cyclominae , reduction of the funicle segments is rare and usually limited to 6-segmented funicles, such as in Hypocolobus Schoenherr, 1842 (Hipporhinini). In other subfamilies, a genus with 3-segmented funicles is Mahnertia Osella, 1978 , with three species from Kenya ( Osella 1978).

This genus was described in Molytinae (Hylobiinae sensu Osella) and is now classified in Cossoninae, tribe Dryotribini ( Alonso-Zarazaga & Lyal 1999) . The reduction in the number of funicle segments, down to 4 segments, is indeed frequently observed in Cossoninae. More species with 4-segmented funicles are present in other subfamilies, and are relatively common in Dryophthorinae. Also, one species of Notiomimetes Wollaston, 1873 (Notiomimetini, belonging to a more basal curculionid lineage according to Gillett et al. 2018) has 4-segmented funicles ( Oberprieler et al., 2014). In Platypodinae various species with 3-segmented funicles are known.