Scopaeus balkei, Frisch & Mainda, 2022

Frisch, Johannes & Mainda, Tobias, 2022, The Scopaeus kokodanus species group (Coleoptera: Staphylinidae: Paederinae) from New Guinea and the Solomon Islands, with description of three new species, Soil Organisms 94 (3), pp. 139-147 : 143-146

Scopaeus balkei spec. nov.

( Figs 3 , 6 , 11–13 , 19, 20, 24 )

Type specimens: Holotype ♂, Indonesia, Papua, Cyclops Mts (02°33’13’’S, 140°34’34’’E), vegetated sandbank of a small stream, 300 m, 11.06.2019, leg. Bretschneider ( ZMBC) . Paratypes (5 specimens): 4 ♂, same data as holotype ( MFNB) ; 1 ♂, Indonesia, Papua, Foja Mts (02°27’32’’S, 138°46’30’’E), gravel bank of a small stream, 300 m, 28.05.2019, leg. Bretschneider ( MFNB) .

Diagnosis: Body shape and coloring as in Fig. 3 . Total body length 3.6 – 3.9 mm; forebody length 2.1 – 2.3 mm. Head slightly elongate, non-pyriform but subcircular, 1.08 – 1.16 (Ø 1.12) times as long as wide, with convex tempora evenly narrowed towards round posterior margin, across eyes 1.27 – 1.33 (Ø 1.36) times as wide as across tempora at half of their length from eyes to neck constriction. Eyes 0.6 – 0.63 (Ø 0.61) times as long as tempora. Elytra about as long as pronotum. Penultimate segment of antenna about 1.2 times as long as wide. Tibia of mesothoracic leg 6.7 – 8.2 (Ø 7.6) times as long as wide. Body black-brown except for yellow distal fifth of elytra, medium brown maxillary palpi, yellow-brown legs with medium brown femora, and antennae with medium brown segments 1 and 2 followed by blackened segments 3 – 6, which are gradually lighter towards yellowish brown segments 7 – 11.

Male: Aedeagus ( Fig. 6 ) about 0.7 mm long; apical lobes in lateral view with ventrally curved dorsal margin with longitudinally bent apex and almost right angled extended ventrally ( Fig. 11 ), in dorsal view ( Fig. 13 ) not widened laterally, but convex towards round apex, their distoventral margins circular in ventral view ( Fig. 12 ); lateral lobes about as wide as long ( Figs 12, 13 ); dorsal lobe stout with round apex in dorsal view ( Fig. 13 ). Asetose median depression of abdominal sternite VII ( Fig. 19 ) with parallel lateral margins. Abdominal sternite VIII ( Fig. 20 ) with median lobe of posterior margin as long as lateroposterior angles; end of median lobe notably emarginate; four distinct, pigmented macrosetae situated close to posterior margin of sternite.

Distribution: Scopaeus balkei was collected in the Cyclops and Foja Mountains ( Fig. 25 ) in the Indonesian province of Papua, western New Guinea.

Comparative notes: Among the members of the Scopaeus kokodanus species group, S. balkei ( Fig. 3 ) differs from both S. kokodanus ( Fig. 1 ) and S. arfakmontium ( Fig. 2 ) by smaller body size and non-pyriform head. The species can moreover be separated from S. arfakmontium by the yellow apical margin of the elytra, the smaller aedeagus with stouter lateral lobes, laterally not widened, but ventrally angled extended apical lobes and round apex of the dorsal lobe ( Figs 11– 13 ), and by the posterior margin of abdominal sternite VII with shorter median lobe and the presence of four distinct, dark macrosetae ( Fig. 20 ). Scopaeus balkei differs from S. potamides by the darker body coloring and characters of the aedeagus and abdominal sternites VII and VIII described below.

Etymology: With the choice of the epithet ‘ balkei ’ (Latinized noun, derived from the surname ‘Balke’, genitive) we warmly dedicate the species to Michael Balke, coleopterist at the Zoologische Staatssammlung Munich, who actively supports the second author in his entomological activities.

Figures

Figure 25. Habitat of Scopaeus balkei in the Foja Mountains, Indonesia, Papua Province.

Figures 1–4. Habitus of Scopaeus kokodanus, Papua New Guinea, Morobe, Waritaian (1), S. arfakmontium, paratype, Indonesia, West Papua,Arfak Mts (2), S. balkei, paratype, Indonesia, Papua, Cyclops Mts (3), S. potamides, paratype, Solomon Islands, Kolombangara (4).

Figures 5–7. Aedeagus (in lateral view) of Scopaeus arfakmontium, holotype, Indonesia, West Papua, Arfak Mts (5), S. balkei, holotype, Indonesia, Papua, Cyclops Mts (6), S. potamides, holotype, Solomon Islands, Kolombangara (7). Abbreviations: dl – distal lobes, pb – phallobase.

Figures 8–16. Apical portion of aedeagus in lateral (8, 11, 14), ventral (9, 12, 15), dorsal view (10, 13, 16) of Scopaeus arfakmontium, holotype, Indonesia, West Papua, Arfak Mts (8–10), S. balkei, holotype, Indonesia, Papua, Cyclops Mts (11–13), S. potamides, holotype, Solomon Islands, Kolombangara (14–16). Abbreviations: al – apical lobes, dl – dorsal lobe, f – flagellum, ll – lateral lobe.

Figures 17–24. Abdominal sternite VII (17, 19, 21) and abdominal sternite VIII (18, 20, 22) of Scopaeus arfakmontium, holotype, Indonesia, West Papua,Arfak Mts (17, 18), S. balkei, holotype, Indonesia, Papua, Cyclops Mts (19, 20), S. potamides, paratype, Solomon Islands, Kolombangara (21, 22), S. kokodanus (23). Figs 23, 24: sperm pumps of (23) S. kokodanus, Papua New Guinea, Morobe, (24) S. balkei, paratype, Indonesia, Papua, Cyclops Mts.