Xiphoscelis namibica Perissinotto

Perissinotto, Renzo & Sipek, Petr, 2019, New species of Xiphoscelis Burmeister, 1842 (Coleoptera, Scarabaeidae, Cetoniinae) from arid regions of South Africa and Namibia, ZooKeys 879, pp. 57-89 : 57

publication ID	https://dx.doi.org/10.3897/zookeys.879.37721
publication LSID	lsid:zoobank.org:pub:D2A33EC1-971E-4CCA-B288-37BA8E186C59
persistent identifier	https://treatment.plazi.org/id/FA69288D-39FB-44C3-B900-E62AC514097F
taxon LSID	lsid:zoobank.org:act:FA69288D-39FB-44C3-B900-E62AC514097F
treatment provided by	ZooKeys by Pensoft
scientific name	Xiphoscelis namibica Perissinotto
status	sp. nov.

Treatment

Xiphoscelis namibica Perissinotto sp. nov. Figs 2 View Figure 2 , 5 View Figure 5

Diagnosis.

Xiphoscelis namibica can best be separated from both X. schuckardi and X. braunsi by the characteristics of its parameres, as it is the only species among the three to exhibit an apical protuberance on the inner margin of each dorsal lobe ( Fig. 5 A–C View Figure 5 ). There are also external morphological characters that can be used in the diagnosis of this species, the most prominent of which are clypeal shape and the size of the metatibial spurs. Unlike in the other two species, in X. namibica the anterior margin of the clypeus ranges from being weakly sinuate to straight, while the lateral margins are arcuate like those observed in X. schuckardi ( Fig. 2D View Figure 2 ). The metatibial spines and spurs are generally hypertrophic in the genus Xiphoscelis , with the internal spine normally exceeding the thickness and length of the spurs by several fold and attaining extreme disproportions in males ( Perissinotto et al. 2003). In X. namibica , however, the metatibial spurs are as long as the inner spine in both sexes and neither of them reaches lengths comparable to those observed in the other two species under comparison ( Figs 1 View Figure 1 - 3 View Figure 3 ).

Description of holotype male.

( Figs 2 A–E View Figure 2 , 5 A–C View Figure 5 ) Size. Length 14.3; width 8.0 mm.

Body. Completely black and matte, except for small worn ridges on elytral umbones ( Fig. 2A View Figure 2 ); head and pronotum of normal proportions with respect to abdomen size; metacoxa, abdominal sternites and pygidium moderately protruding outside elytral margins; with scattered and shallow sculpture throughout dorsal surface associated with short to medium dark setae, becoming longer and denser on antero-lateral margins (mostly fallen or broken due to specimen being retrieved from the field sometime after death, Fig. 2A, C, D View Figure 2 ).

Head. Entirely black, with coarsely round sculpture throughout surface; ultrafine rugosity across entire surface; long, erect black setae on eye canthus and antennal pedicel; clypeus weakly bilobate but deeply concave, with both anterior and lateral margins equally elevated, lateral margins smoothly rounded all around; antennal clubs, flagellum and pedicel black and of normal cetoniine length; pedicel becoming lighter and brown towards base.

Pronotum. Black and matte; regularly round in shape, except at antero-lateral margins, where sharp angles lead to medio-apical, moderately elevated transversal protuberance; posterior margin forming perfectly straight line in front of scutellum; round punctures regularly spaced across surface, but becoming more scattered on disc and denser at margins and on lateral declivities; thick, black, setae of medium length visible only on lateral margins ( Fig. 2 A, C View Figure 2 ).

Scutellum. Completely black; isoscelic triangular with weakly rounded apex and lateral grooves absent on basal third but well developed along other two-thirds towards apex; with dense but irregularly shaped punctures on basal and baso-lateral margins, but absent on central part of disc and on apical third; few, thick and black erect setae scattered across basal third of surface ( Fig. 2A View Figure 2 ).

Elytron. Completely black and matte, narrower than abdomen leaving apical projection of sternites and pygidium partly exposed; subhumeral arch very low and postero-apical declivity extremely steep and abrupt; all costae subequally and weakly elevated, with 5th and 6th costae and umbones raised; surface densely sculptured with geminate striae or round to irregular punctures along intercostal spaces, becoming very sparse and occasional on surface of costae; sparse short, but thick and erect black setae across whole surface, except umbones; apex with short but distinct spinal projection ( Fig. 2A, B View Figure 2 ).

Pygidium. Completely black, narrow and broadly triangular in shape, with basal and lateral margins sharply upturned; with uniformly sparse horse-shoe sculpture across surface; convex with small baso-lateral depressions; without pubescence on general surface but with lining of black, long setae along lateral and apical margins ( Fig. 2E View Figure 2 ).

Legs. All legs black in dorsal view, with tarsal segments elongate, but tibiae of normal cetoniine thickness and length; protibia tridentate, with proximal tooth reduced and other two teeth severely worn; mesotibia exhibiting mid outer spine, two apical spines and two spurs of small to medium size; metatibia with slightly hypertrophic inner spine and spurs, inner spine much thicker but shorter than spurs ( Fig. 2 A–C View Figure 2 ); femora reddish-brown at base, becoming black distally and at joints, bearing long, thin dark setae; pro- and meso-femora of normal size, but metafemora hypertrophic.

Ventral surface. Shiny and black, with reddish-brown areas restricted to part of coxae and basal portion of femora; with thin and long dark setae on prosternum, coxae and all femoral margins, becoming shorter and more sparse on other surfaces, particularly abdominal sternites; all setae emerging at centre of small and round sculptures; mesometasternal process extremely small, not protruding forward or upwards and partly covered by coxal bases, black and with scattered round punctures and thin setae on surface; abdominal sternites slightly convex, becoming flat at middle particularly in area of sternites 5-7.

Aedeagus. Parameres with dorsal lobes tapering abruptly towards apex, forming steeply elevated apical spine at inner end, covering completely ventral lobes in dorsal view ( Fig. 5A View Figure 5 ); exhibiting long, thin setae along entire apical margin ( Fig. 5 A–C View Figure 5 ); apical surface approximately circular in frontal view ( Fig. 5C View Figure 5 ).

Derivatio nominis. With the exception of one female from O’Kiep (South Africa), so far, all the specimens known for this species and representing the type series originate from the same locality, in south-western Namibia. Hence the obvious geographic link to its name.

Description of female.

Unlike with all the other species of the genus, it is virtually impossible to separate the two sexes of X. namibica on the basis of external morphology alone. This is because the metatibial internal apical spine and spurs of its male ( Fig. 2 A–C View Figure 2 ) are just as poorly developed as those of the female: a truly unique situation within this genus, with essentially no detectable sexual dimorphism. The only characters where some difference can be observed with a well-trained eye are the relatively shorter protibial and protarsi of the female versus those of the male counterpart, as well as the slight concavity of the abdominal sternites in the male.

Distribution.

So far, the few specimens known for this species have been collected mostly in south-western Namibia, near the town of Rosh Pinah, in the Namuskluft area at about 1200 m asl ( Fig. 7 View Figure 7 ). One female specimen is also known from O’Kiep, in the South African Northern Cape. Thus, the species appears to be an arid mountain specialist, possibly occurring throughout the Ai-Ais Huns Mountains, the Richtersveld range and nearby areas above the Great Escarpment.

Biology.

The holotype and paratype series collected by Holm & Gebhardt in southern Namibia were all retrieved dead from middens of the southern harvester termite Microhodothermes viator . Given the very limited number of observations available for this species, it is not possible to establish whether or not this is a case of obligatory association, or again a rather opportunistic one.

Type material.

Holotype (♂): Namibia, Namuskluft, 1200 m, 27°45'S, 16°53'E, 2-6 Apr 2002, in Microhodothermes viator middens, E. Holm & H. Gebhardt (ISAM). Paratypes: 3 ♂, 2 ♀, same data as holotype (BMPC); 1♀, South Africa, Northern Cape, O’Kiep 29°35S, 17°52E, 1885-11-10, L. Péringuey leg. ( SANC–COLS– 12181).