Exocelina pseudopusilla Shaverdo & Balke

Shaverdo, Helena, Sagata, Katayo & Balke, Michael, 2018, Introduction of the Exocelinacasuarina-group, with a key to its representatives and descriptions of 19 new species from New Guinea (Coleoptera, Dytiscidae, Copelatinae), ZooKeys 803, pp. 7-70 : 32-35

18. Exocelina pseudopusilla Shaverdo & Balke sp. n. Figs 18, 42

Type locality.

Papua New Guinea: Simbu Province, Mount Wilhelm, 05°43'15.145"S, 145°16'10.0927"E, 1,200 m a.s.l.

Type material.

Holotype: male "Ibisca Niugini, PNG 1-3.xi.2012 Mount Wilhelm 1200 m -5,720873833 145,2694702 MW1200 / P1611 Vial 16950" (MNHN). Paratypes: 1 male "Ibisca Niugini, PNG 27-29.x.2012 Mount Wilhelm 1200m -5,720873833 145,2694702 MW1200 / P1513 Vial 09099" (IECA). 1 male "Ibisca Niugini, PNG 27-29.x.2012 Mount Wilhelm 1200m", " -5,720873833 145,2694702 FIT-MW1200-E-2/8-d03 / Plot 5 / P1521 Vial 17210" (NHMW). 1 female "Ibisca Niugini, PNG 27-29.x.2012 Mount Wilhelm 1200m -5,720873833 145,2694702 MW1200 / P1553 Vial 09007" (ZSM). 1 female "Ibisca Niugini, PNG 27-29.x.2012 Mount Wilhelm 1200m -5,720873833 145,2694702 MW1200 / P1561 Vial 16873" (ZSM). 1 female "Ibisca Niugini, PNG 28-30.x.2012 Mount Wilhelm 1200m -5,720873833 145,2694702 MW1200 / P1601 Vial 17313" (ZSM). 1 female "Ibisca Niugini, PNG 28-30.x.2012 Mount Wilhelm 1200m -5,720873833 145,2694702 MW1200 / P1633 Vial 18848" (MNHN). 2 females "Ibisca Niugini, PNG 28-30.x.2012 Mount Wilhelm 1200m -5,720873833 145,2694702 MW1200 / P1609 Vial 18855" (BMNH, ZSM). 1 female "Ibisca Niugini, PNG 28-30.x.2012 Mount Wilhelm 1200m -5,720873833 145,2694702 MW1200 / P1633 Vial 18848" (ZSM). 1 female "Ibisca Niugini, PNG 30.x.-1.xi.2012 Mount Wilhelm 1200m -5,720873833 145,2694702 MW1200 / P1634 Vial 17605" (ZSM). 1 female "Ibisca Niugini, PNG 27-29.x.2012 Mount Wilhelm 1200m", " -5,720873833 145,2694702 FIT-MW1200-G-2/8-d03 / Plot 7 / P1537 Vial 17367" (ZSM). 1 female "Ibisca Ni ugini, PNG 28-30.x.2012 Mount Wilhelm 1200m", " -5,720873833 145,2694702 FIT-MW1200-S-2/8-d04 / Plot 19 / P1633 Vial 18847-CODYTI" (ANIC).

Description.

Body size and form: Beetle small: TL-H 3.25-3.55 mm, TL 3.65-3.95 mm, MW 1.8-1.85 mm (holotype: TL-H 3.5 mm, TL 3.85 mm, MW 2.0 mm), with oblong to oblong-oval habitus.

Coloration: Reddish brown to dark brown, with head and pronotum paler. Head reddish to reddish brown, with small darker areas posterior to eyes. Pronotum reddish to reddish brown, with dark brown disc. Elytra brown to dark brown, with narrow reddish sutural lines. Head appendages yellowish red, legs reddish, distally darker, especially metathoracic legs (Fig. 18). Teneral specimens paler.

Surface sculpture: Submatt dorsally. Head with dense, coarse punctation (no spaces between punctures or spaces of equal size of punctures), evidently finer and sparser anteriorly; diameter of punctures equal to or larger than diameter of cells of microreticulation. Pronotum and elytra with dense and coarse punctation, sparser and finer than on head. Pronotum and elytra with rather strongly impressed microreticulation. Head with microreticulation stronger. Metaventrite and metacoxae distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal ventrites with distinct microreticulation, strioles, and fine sparse punctation.

Structures: Pronotum with narrow lateral bead. Its lateral sides with distinct longitudinal impressions. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct lateral bead and few setae. Abdominal ventrite 6 slightly truncate or very slightly concave.

Male: Antennae simple (Fig. 18). Protarsomere 4 with anterior angle slightly expanded, with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 long and narrow, with anterior band of ca 40 and posterior row of 13 relatively long, thin setae (Fig. 42D). Median lobe in lateral view simple, slightly curved; in ventral view, evenly tapering to broadly pointed apex, side of apex slightly thickened. Paramere slightly concave on dorsal side and with dense setae on subdistal part; proximal setae finer (Fig. 42 A–C). Abdominal ventrite 6 with 9-10 lateral striae on each side.

Female: Without evident differences in external morphology from males, except for not modified protarsi and abdominal ventrite 6 without striae.

Affinities.

Exocelina pseudopusilla sp. n. is similar to E. pusilla sp. n. but larger, more elongate, with denser and coarser dorsal punctation and microreticulation and differently shaped median lobe. See also under E. cyclops sp. n.

Distribution and note on taxonomy. Papua New Guinea: Simbu Province (Fig. 50). So far, this species is known only from the Mount Wilhelm, where it occurs at the high altitudes (1200 m), whilst E. pusilla sp. n. is also known from the Mount Wilhelm but only from 200 m. We consider the specimens from 1200 m as a distinct species (not belonging to E. pusilla sp. n.) because of the morphological differences mentioned above and because no intermediate forms were found. We realize a possibility that they might be just a larger, more elongate, and more strongly punctured and reticulated form of E. pusilla sp. n. adapted to the high altitudes. However, based on the present material, we cannot confirm it. For that, further morphological and molecular studies and more material, including one from intermediate altitudes, are requited.

Etymology.

The species was mistaken for E. pusilla sp. n. due to their similarity. The name is a noun in the nominative singular standing in apposition.