Echinothallis Skelley, Leschen & Liu, 2021

Skelley, Paul E., Leschen, Richard A. B. & Liu, Zhenhua, 2021, New Australian Erotylinae with notes on Dacnini (Coleoptera: Cucujoidea Erotylidae), Zootaxa 4948 (3), pp. 363-380 : 364-365

Echinothallis Skelley, Leschen & Liu , new genus

Type species. Echinothallis banderbearella, Skelley, Leschen, Liu , new species, by present designation.

Diagnosis. A member of the Dacnini with prominent anterior pronotal margin and narrow tetramerous tarsi. Echinothallis is distinguished from other genera by the coarsely facetted eyes, elongate, somewhat parallel-sided body, posterior pronotum and elytral base with marginal bead, mesocoxae narrowly separated, mental plate triangular, terminal palpomere of maxilla flattened and wider apically, and the heavily punctate and setose body.

Description. Length 3.6–3.9 mm; width 1.3–1.4 mm. Body elongate, somewhat parallel-sided body ( Figs. 1–3 ).

Head with sides narrowing anteriorly; supraocular stria as long as eye, ending near base of antenna. Eyes coarsely faceted; almost oval, prominent; with setae between facets. Stridulatory files on occipital region absent. Mentum with plate broadly triangular, width 2× length, coarsely punctate; median projection small. Submentum short, transverse; surface and groove behind with large, deep punctures. Maxilla with terminal palpomere flattened, length = apical width, narrowed basally, apically prolonged medially, sensory apex truncate. Labium with terminal palpomere narrowed toward base, apically flattened, width 0.5× width of terminal maxillary palpomere; apical sensory area elongate.

Pronotum convex, anterior margin lacking marginal bead; anterior angles blunt, not projecting forward, surface explanate at angle; lateral margin gently arched, convergent anteriorly and posteriorly, with fine marginal bead, and fringe of irregularly long setae; posterior angles sharp, projecting posteriorly; posterior margin of pronotum weakly lobed at middle, marginal bead present, obscured in surface sculpture.

Scutellar shield broadly, roundly pentagonal. Elytra elongate, length 1.8× pronotal length; base with marginal bead present, obscured in surface sculpture; lateral margin evenly arcuate from base to apex, widest at midlength; humeral denticles present, small. Wings apparently lacking, elytra fused.

Legs slender and densely hirsute. Femora fusiform, somewhat flattened, with two sharp edges on inner surface. Tibiae slender, slightly curved basally; apex with fringe of moderately long spinules. Tarsi elongate, cylindrical, tarsomeres 1–3 densely setose ventrally but not lobed, tarsomeres 1–4 more or less of same size; tarsomere 5 slightly shorter than preceding four tarsomeres.

Prosternum anterior margin with strong marginal bead; anterior margin of procoxa with line; procoxal lines present between coxa, not extending anteriorly, weakly extending posteriorly onto prosternal process where obscured in dense punctation; prosternal process parallel-sided between coxae, widening posterior of coxae, width between procoxa about = transverse diameter of coxa; posterior margin truncate; pores on prosternal process not observed. Hypomeron with deep coarse punctures bearing long setae, punctures separated by 1 diameter.

Mesoventrite flattened covered with deep seta bearing punctures as large as facets, punctures coalescing; mesometaventrite suture narrow, distance between mesocoxae narrower than the width of mesocoxa.

Metaventrite moderately short, length between meso- and metacoxa 1.5× distance between mesocoxae; anterior margin distinctly bordered medially; coxal lines extending onto surface 2/3 distance to posterior margin; anterior marginal line obscured in coarse punctures behind mesocoxae; metathoracic discrimen and coxal lines obscured in coarse punctation. Metanepisternum narrow, covered with scattered seta bearing punctures.

Abdomen with ventrite 1 anterior process bluntly rounded; two coxal lines present, first extending from medial margin of metacoxal cavity nearly to posterior margin of ventrite 1, second short line extending posteriorly from lateral 1/3 of mesocoxal cavity; anterior margin of ventrite 1 behind metacoxae distinctly bordered.

Male genitalia ( Figs. 5–8 ) with penis short, arched; median strut and flagellum long; penis length = 0.3× median strut length; internal sac with weak microsetae in caudal half; flagellum with small elongate oval head, virga long, as long as median strut, hair-like; parameres bluntly rounded apically, with long setae; abdominal sternite IX broad, truncate, sides of spiculum gastrale separated anteriorly by oval sclerite together they form a pregenital ring.

Female genitalia ( Fig. 4 ) with normally sclerotized gonocoxite and gonostylus, gonostylus distinct and set apically on gonocoxite; segment IX lacking denticulate lamellae; head of spermatheca elongate oval, with short sclerotized duct.

Etymology. The genus name is derived from two roots: “ echino ” Greek for spiny and “ Thallis ” a genus of Dacnini in which it was considered to initially belong. Gender feminine.

Remarks. At first look this new genus and species appeared to be a new species of Thallis Erichson which has a range of species from glabrous to hairy, some already described from Australia (other species occur in New Caledonia and the Moluccas). However, closer examination show that Echinothallis is unlike typical species of Thallis , including the hairy species, in many important characters that are lacking in some other dacnines (see below). Further studies of currently described species of Thallis shows it to be an accumulation of species groups that may be valid genera themselves (see Skelley & Leschen 2007). A revision of Thallis is needed to resolve that problem which is outside the scope of the present work. Since Echinothallis falls outside of the current concept of Thallis , it is here described as a prelude to this revision.

Figures

FIGURES 1–8. Echinothallis banderbearella sp. nov.: 1–3) habitus, holotype; 1) dorsal view; 2) ventral view; 3) lateral view; 4) female genitalia, allotype; 5–8) male genitalia, paratype; 5) abdominal segments VIII–IX, ventral view; 6) tegmen, dorsal view; 7) penis, lateral view; 8) penis, dorsal view. Scale bars: 1–3 = 1.0 mm, 4–8 = 0.2 mm.