Desertilydus 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 : 30-31

Desertilydus Bologna gen. n.

Type species. Lytta mesembryanthemi Péringuey, 1888 , fixed by monotypy and present designation.

Diagnosis. A monotypic lyttine genus ( Fig. 1Y ) similar in shape to Lydomorphus Fairmaire, 1882 particularly because of the slender body and pronotum, but greatly distinct because of the head dorsally almost flat, eyes ventrally not extended medianly under head, antennae very short in both sexes not reaching base of pronotum, male last ventrite lacking apical laminar expansions, male gonostyli well sclerotized, body setation reduced. Desertilydus differs from the new genus Dilatilydus because of the head almost flat dorsally and the antennae greatly shorter and male gonoforceps wider and narrowed only in apical third, not curved posteriad, and body scarcely setate.

The type species, endemic to Namibian and South African Namaqualand and to northern Karoo, was referred by Kaszab (1955a, as Cylindrothorax ) to a distinct group (XXII). We herein refer it to a new genus, well distinct from Lydomorphus at least by the shape of last male ventrite without laminar expansion; eyes not extended ventrally, head dorsally very flat, antennae very short and robust.

Description. Characters of the type species. Body ochre, but ventral and lateral sides of head, antennae and mouthparts, legs and usually episternites and a narrow portion of elytral apex black ( Fig. 1Y ). Dorsal surface of head and pronotum glabrous, elytra with short and scattered dark setae, ventral surface with dark short setae denser than on dorsal surface, very dense on coxae and throchanters. Elytra not covering completely the abdomen, especially in female but also in some males. Body sligthly obtuse, length 11–15 mm.

Head shortly subrectangular, with temples parallel in both sexes widely curved posteriorly, sligthly shorter than longitudinal diameter of eye. Mandibles longer than labrum, at apex narrowed and pointed; maxillary and labial palpomeres not modified; clypeus greatly shorter than labrum, labrum at apex almost straigth or scarcely emarginated. Antennae short and not modified in both sexes. Male antennomere I sligthly shorter than III, more than two times II; II very short and subglobose; III–XI cylindrical, III about 1.5 times as long as IV, IV–X similar in length; XI cylindrical but greatly narrower in apical third and pointed at apex with dense small yellow setae. Female antennomeres similar to those of male, just scarcely more submoniliform, but last antennomere slightly less narrowed. Pronotum narrow and slender, suboval, slightly converging in fore third, without dorsal depressions. Thoracic ventrites not modified. Elytral external margin in lateral view sligthly emarginated in middle. Legs non modified in both sexes; tarsomeres without ventral pads; pro- and metatibial spurs elongate and pointed, metatibial external spur spoon-like not pointed at apex.

Ventrites not modified; last male sternite V-emarginated, longitudinally depressed in middle, without laminar expansions, that of female not emarginated. Male genitalia with gonoforceps longer than gonocoxal base, wider and parallel in the basal 2/3, narrowed at apex, with a wide depressed oval area on dorsal fore portion, not curved posteriad, dispersely setate, particularly on dorsal side of apical third, and with spiniform setae on ventral side at apex; aedeagus with two pointed and thin hooks both far from apex, subequal in length.

Etymology. The name of the new genus refers to its ecological relation to southern African desert ecosystems (mainly Namib, Nama and Succulent Karoo), and is composed also by Lydus , the name of another lyttine genus, in assonance with the name of two subgenera of Lydomorphus and to Dilatilydus . Masculine genus.

Remarks. Kaszab (1955a) pointed out the very distinct position of this species. Affinities of this genus are completely unkwnon, even if, according to molecular analyses (Pitzalis et al. in preparation), it appears isolated and very distinct from Lydomorphus and from another Saharo-Sahelian new lineage of Lyttini similar in shape to Lydomorphus . As both this last taxon and Dilatilydus , it lacks the shared condition of modified last ventrite (see above). The general shape of pronotum and male genitalia seems more similar to that of Lydomorphus than to other genera of Lyttini

This genus is diurnal, differently than Lydomorphus and Dilatilydus .

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.