Deleaster wilhelmensis, Shaw & Eos & Llc & Cs & Cs, 2018

Shaw, Josh Jenkins, 2018, Significant range expansion for the rove beetle genus Deleaster, based on a new species from Papua New Guinea (Coleoptera: Staphylinidae: Oxytelinae), Acta Entomologica Musei Nationalis Pragae 58 (1), pp. 21-24 : 22-23

Deleaster wilhelmensis sp. nov.

Type locality. Papua New Guinea, Eastern Highlands, Mt. Wilhelm, Pengal River, 9200 ft. [ca. 2760 m], [approximate coordinates: 5 ° 47ʹS 145 ° 05ʹE.

Type material. HOLOTYPE: ♀: “ New Guinea, Eastern Highlands, Mt. Wilhelm.Pengal River, 9200 ft., 16.5- 9.6.1963. W.W.Brandt // Deleaster det. A.F. Newton 1987 // ANIC Specimen [green label] // HOLOTYPE Deleaster wilhelmensis sp. nov. Jenkins Shaw des. 2017”. The holotype is deposited in the Australian National Insect Collection ( ANIC).

Description. Measurements (all in millimeters): HW = 1.41; TW = 1.13; PW = 1.33; SW = 2.26; AW = 2.43; Hl = 1.03; el = 0.55; Tl = 0.27; Pl = 1.13; sl = 2.55; sC = 2.23; FB = 4.9; Bl = 7.6.

Habitus as in Fig. 1A . Overall dark brown with head appearing slightly darker, almost black. Antennae dark brown. Legs light brown; tarsi slightly paler than tibiae and femora.

Head excluding clypeus transverse; clypeus strongly produced with two pairs of small punctures situated laterally. Head and clypeus with linear microsculpture. Vertex with two punctate impressions extending from posterior edge of head to inner margin of eyes. Labrum weakly emarginate. Frontoclypeal (epistomal) suture distinct ( Fig. 1B : fs). Temples with weak setiferous punctures. Neck with distinct transverse microsculpture. Antennae with first antennomere distinctly thickened compared to subsequent antennomeres; third antennomere as long as first antennomere. Antennal insertions almost obscured in dorsal view. All antennomeres with both macro and micro setae. Apical area of antennomeres six to ten with short, stout white setae (referred to as ‘ciliae’ by HAYASHI (1984)).

Pronotum widest anteriorly, weakly narrowed posteriorly; front angles forming an evenly rounded right angle; hind angles evenly rounded. Dorsal surface with distinct linear microsculpture and weak punctures throughout, the distance between the punctures equal to the diameter of two or three punctures combined. Pair of larger punctures present towards anterior margin of pronotum. Laterobasal areas of pronotum each with impression extending halfway along edge of pronotum, with some micro setae at the posterior end of each impression. Central basal area with distinct transverse impression. Hypomeron large; covered with microsculpture ( Fig. 1C : hy). Apex of basisternum acute. Scutellum slightly paler than elytra; with rugose microsculpture and pale pubescence. Elytra widest at apical third; confusely but weakly punctured with short pale setae; weak rugose microsculpture present between elytral punctures. Hind wings apparently present (not studied), folded under elytra. Legs rather long and slender; fifth tarsomere as long as one to four combined. Claws half the length of fifth protarsomere.

Abdomen broadest at tergite IV. Tergites covered in short pale setae; weak transverse microsculpture present except at medioapical area of each tergite. Tergites III to VI with widely separated pair of long golden macro setae situated close to posterior margin; tergite VII with two pairs of widely seperated long golden macro setae situated close to posterior margin. Tergite VIII with middle of apical margin deeply incised, forming pair of small teeth, each bordered by a long lobe ( Fig. 1D ).

Differential diagnosis. Aside from being a geographic outlier within the genus ( Fig. 2 ), D. wilhelmensis may be distinguished from congeners based on the following combination of characters: overall dark brown colouration; pronotum without pubescence; distinctly wide and rounded lateral contour in apical third of elytra; abdomen widest at tergite III; tergite VIII with middle of apical margin deeply incised, forming pair of small teeth, each bordered by a long lobe ( Fig. 1D ). CUCCODORO & MAK- RANCZY (2013) were the first to mention and illustrate the structure of tergite VIII in the genus and in the Afrotropical Deleaster they noted the shape was similar in both sexes. Deleaster wilhelmensis can be distinguished from congeners based on the following: from D. dichrous (Gravenhorst, 1802) and D. trimaculatus Fall, 1910 by the dark colouration of the elytra; from D. pectinatus Fauvel, 1882, D. gibbosus Cuccodoro & Makranczy, 2013 and D. negus Cuccodoro & Makranczy, 2013 by the shape of tergite VIII (middle of apical margin deeply incised, forming pair of small teeth, each bordered by a long lobe); from D. yokoyamai Adachi, 1935 by the presence of microsculpture on the head, longer second antennomere compared to third and lack of pubescence on the pronotum; from D. bactrianus Semenow, 1900 by the longer second antennomere compared to third, front angles or pronotum evenly rounded (obtuse in D. bactrianus) and abdomen widest at tergite IV (tergite V in D. bactrianus); from D. taiwanensis Hayashi, 1984 by the abdomen widest at tergite IV (tergite V in D. taiwanensis) and shape of tergite VIII (described as ‘shallowly emarginate’ for D. taiwanensis by HAYASHI (1984)).

Etymology. The species name refers to the fact that the only known specimen of D. wilhelmensis was collected from Mount Wilhelm, Papua New Guinea. It is an adjective derived from the mountain’s name.

Distribution and bionomics. The single known specimen was collected from Mount Wilhelm at about 2760 m with the locality given as Pengal River ( Fig 2 ). According to BISHOP MUSEUM (1966) and SIBATANI (1974), Pengal River as referred to in Brandt’s collection is ‘Pengal R (upper), 5 ° 47’ 145 ° 05’, 2760 m’ and is apparently on the east side of Mount Wilhelm and the northern slope of the Bismarck Range, upstream of the Imbrum River. Although the precise habitat or method of collecting for this specimen is unknown, most likely it is a riparian. It is notable that all known species of Deleaster are confined to wet habitats (e.g. stream banks, leaf litter, caves, under stones) and often in mountainous regions ( GREBENNIKOV 2002).

Figures

Fig 1. Morphology of Deleaster wilhelmensis sp. nov. A – habitus of holotype B – head (fs – frontoclypeal suture). C – lateral view of head and prothorax (hy – hypomeron). D – tergite VIII.

Fig 2. Distribution of extant Deleaster Erichson, 1839.