Scopaeus potamides, 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 : 146-147

Scopaeus potamides spec. nov.

( Figs 4 , 7 , 14–16 , 21, 22 )

Type specimens: Holotype ♂, Solomon Islands, Kolombangara , Kuzi , Camp 1, 07.09.1965, flood refuse between stones, banks of Kolombara River, leg. Royal Society Expedition, British Museum 1966-1 ( NHML) . Paratype 1 ♂, same data as holotype ( MFNB) .

Diagnosis: Body shape and coloring as in Fig. 4 . Total body length 3.6 – 3.8 mm; forebody length 2.3 – 2.4 mm. Head slightly elongate, non-pyriform but subcircular, 1.1 times as long as wide, with convex tempora evenly narrowed towards round posterior margin, across eyes 1.17 – 1.28 (Ø 1.23) times as wide as across tempora at half of their length from eyes to neck constriction. Eyes 0.64 – 0.71 (Ø 0.68) times as long as tempora. Elytra 1.1 times as long as pronotum. Penultimate segment of antenna about 1.3 times as long as wide. Tibia of mesothoracic leg about seven times as long as wide. Head and pronotum reddish brown, elytra dark brown except for yellow posterior fifth, abdomen dark brown, appendages (maxillary palps, antennae, legs) unicolorous light yellow-brown.

Male: Aedeagus ( Fig. 7 ) about 0.8 mm long; apical lobes in lateral view with strongly S-shaped ventroapical margin and obtusely extended ventrally ( Fig. 14 ), in ventral and dorsal view ( Fig. 15, 16 ) stout and somewhat narrowed towards clipped apex; lateral lobes about as wide as long ( Figs 15, 16 ); dorsal lobe stout with round apex ( Fig. 16 ). Abdominal sternite VII ( Fig. 21 ) with asetose median depression notably narrowed towards posterior margin. Abdominal sternite VIII ( Fig. 20 ) with median lobe of posterior margin as long as lateroposterior angles; end of median lobe slightly emarginate; four distinct, long, black macrosetae situated close to posterior sternite margin.

Distribution: Scopaeus potamides is hitherto known only from Kolombangara Island, Solomon Islands.

Comparative notes: Within the Scopaeus kokodanus species group, S. potamides ( Fig. 4 ) is readily distinguished by the lighter coloring with reddish brown head and pronotum and unicolorous yellowish brown appendages. The species differs from S. kokodanus ( Fig. 1 ) and S. arfakmontium ( Fig. 2 ) by the round, non-pyriform head. It moreover differs from S. arfakmontium by the smaller aedeagus ( Fig. 7 ) with shorter lateral lobes, tapered apical lobes in dorsal view with characteristic shape in lateral view ( Figs 14–16 ), round apex of the dorsal lobe and shorter median lobe of the posterior margin of abdominal sternite VIII, which is not longer than the lateroposterior angles of the sternite ( Fig. 22 ) and lacks a clearly emarginate tip. In addition, S. potamides can be separated from both S. arfakmontium and S. balkei by the posteriorly narrowed asetose median depression of abdominal sternite VII ( Fig. 21 ).

Etymology: With the epithet ‘ potamides ’ (greek noun Ποταμίδες, genitiv) reference is made to the potamids, the seductive river nymphs of the Greek mythology, because representatives of the genus Scopaeus are also inhabitants of streams. As every stream is said to have its own potamid according to the Greek mythology, we dedicate S. potamides to the nameless water nymph of the Kolombara River of Kolombaranga Island, the name of which moreover translates as ‘lord of the waters’.

Figures

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.