Dilatilydus Bologna, 2018

Bologna, Marco A., Amore, Valentina & Pitzalis, Monica, 2018, Meloidae of Namibia (Coleoptera): taxonomy and faunistics with biogeographic and ecological notes, Zootaxa 4373 (1), pp. 1-141 : 29-30

Dilatilydus Bologna gen. n.

Type species. Cantharis optata Péringuey, 1892 fixed by monotypy and present designation.

Diagnosis. A monotypic lyttine genus ( Fig. 1X ), endemic to desert and semidesert regions of northen and western Namibia and northwestern Botswana, similar in shape to Lydomorphus Fairmaire, 1882 because of the slender body and pronotum, and eyes extended ventro-medially under the head, but greatly distinct because of male antennomeres III–V and VIII broadened out externally (see De Moor 1977), the male last ventrite lacking apical laminar expansions, and male gonostyli well sclerotized. Differs from the new genus Desertilydus because of its head sligthlyy convex dorsally, antennae longer, which reach the middle of elytra with male antennomeres modified, and male gonoforceps slender in the apical half, sligtly curved posteriad.

Description. Characters of the type species. Body black subopaque, but pronotum sligthly shiny orange, and elytra pale yellow-brown with base, apex and one middle rectangular spot black ( Fig. 1X ). Body setation whiteyellow, very dense and longer ventrally and on elytra, Body slender, length 12–17 mm.

Head shortly suboval, with temples curved and converging posteriorly, particularly in male, as long as longitudinal diameter of eye. Mandibles longer than labrum, at apex wide and not pointed; maxillary and labial palpomeres not modified; clypeus greatly shorter than labrum, labrum at apex widely emarginated. Male antennomere I about as long than III and more than three times II; II very short and subglobose; III straigth on inner side, but dilated on external side, in middle and more at apex; IV subtrapezoidal, about 2/3 as long as III, greatly widened externally at apex; V about as long as IV but transversally dilated on external side, about twice as wide than long; VI cylindrical and shorter of both V and VII; VII slender and cylindrical; VIII about as long as VI but subtrapeizoidal and widely dilated apically; IX–X slender and cylindrical, about twice as long as VIII; XI cylindrical and slender, progressively narrowed in apical third, longer than X. Female antennomeres all cylindrical and slender, but II very short and subglobose; I and III longer, IV–VIII sligthly shorter than III, VI and VIII slightly shorter than IV–V; IX–X 1.5 as long than VIII, XI 1.5 as long as X.

Pronotum very narrow and slender, subparallel from base to middle, sligthly converging in front; one fore depresion on each side, base depressed also on laterally; thoracic ventrites not modified. Elytral margin, in lateral view, slightly emarginate in posterior half. Legs non modified in both sexes, male protarsomere I widener than in female; tarsomeres with ventral pad of dense yellow setae; pro- and metatibial spurs elongate and pointed, metatibial external spur spoon-like but pointed at apex.

Ventrites not modified; last male sterinte widely V-emarginated without laminar expansions, not evidently depressed medially, that of female not emarginated. Male genitalia with gonoforceps longer than gonocoxal base, slender and progressively narrower from middle to apex, slightly curved posteriad, dispersely setate, particularly on dorsal side of apical third; aedeagus with two pointed hooks both far from apex, proximal one longer.

Etymology. The name of the new genus refers to the dilated shape of male antennomeres III and V, unique in Lyttini , and to Lydus , the name of another lyttine genus. Masculine genus.

Remarks. Affinities of this genus are completely unkwnon. Other new lineages of Old World Lyttini , which are similar in shape to Lydomorphus (namely a new Saharo-Sahelian genus and Desertilydus ), but lacking the shared condition of modified last ventrite (see above), are under molecular study to define relationships among Lyttini (Bologna et al. in preparation). The general shape of both pronotum and male genitalia seems more similar to that of Lydomorphus than other genera of Lyttini .

Kaszab (1955a) examined only females of the type species, but De Moor (1977) described and figured the greatly modified male antennomeres III–V. This male antennal autapomorphic condition, unkwnon to Kaszab (1955a) is one of the most diagnostic characters of the new genus.

As most Lydomorphus also Dilatilydus optatus is nocturnal and attracted by ligth.

Dilatilydus optatus ( Péringuey, 1892) ( Fig. 1X )

Cantharis optata Péringuey, 1892

Cylindrothorax optatus, Kaszab 1955 Lydomorphus optatus, Bologna 2000 Distribution. Botswana and Namibia .

Material examined and literature records. [Ohangwena] Ongenga: Elakalapwe, 17.4000°S 15.7333°E (SMWN). Ondobe: Mafa, 17.5000°S 16.0833°E ( De Moor 1977; Selander 1988a). [Omusati] Outapi: Mahanene, 17.4333°S 14.7833°E (SMWN). Tsandi: Okakundu, 17.8167°S 14.9500°E (CB; SMWN). Ogongo: Iikango, 17.8500°S 15.2333°E (SMWN). [Oshikoto] Olukonda: Ondangwa, 17.9548°S 16.0322°E (CB). Omuthiyagwiipundi: Momtele, 18.3330°S 16.5000°E ( De Moor 1977; Selander 1988a); Andoni Plains, 18.4833°S 16.8000°E (CB; SMWN); Andoni South, Etosha Nat. Park, 18.5167°S 16.7667°E (SMWN). [Kavango] Ndiyona: Kaudom-Cwiba Junctio, Kaudom Game Reserve, 18.4667°S 20.8167°E (SMWN). [Otjozondjupa] Tsumkwe: Bushmanland: Klein Dobe, 19.4167°S 20.3500°E (MNB). [Kunene] Khorixas: Khorixas, 20.3667°S 14.9167°E (PPRI). [Erongo] Dâures: Spitskoppe, 21.8518°S 15.1484°E (SMWN). [Khomas] Windhoek Rural: Nauchas 14, 23.6000°S 16.3500°E (SMWN). [Karas] Lüderitz: near Aus, 26.6667°S 16.2667°E (CP).

Other records: Ovamboland ( Kaszab 1955a); N Ovampoland ( Selander 1988a); Ovampoland ( De Moor 1977); Namibia ( Bologna 2000a; Pitzalis et al. 2014).

Remarks. De Moor (1977) designated the lectotype of this species, we examined at SAMC.

Figures

FIGURE 1. A. Iselma deserticola; B. Iselma hobohmi; C. Iselma penrithae; D. Iselma brunneipes. E. Iselma piscatrix; F. Eletica luteosignata. G. Namibeletica angolana; H. Namibeletica elegantula; I. Afrolytta namaqua; J. Afrolytta amoena; K. Afrolytta carneola; L. Australytta maraisi; M. Australytta rubrolineata; N. Australytta szekessyi; O. Australytta vellicata; P. Lydomorphus chalybaeus; Q. Lydomorphus mimus; R. Lydomorphus bisignatus; S. Lydomorphus strangulatus; T. Lydomorphus karibibensis; U. Lydomorphus thoracicus; V. Lydomorphus tibialis; W. Lydomorphus bifoveiceps; X. Dilatilydus optatus; Y. Desertilydus mesembryanthemi.