Micrillus suturalis ( CAMERON 1930) Assing, 2013

Assing, V., 2013, On the Palaearctic and Oriental species of Scymbalium and Micrillus (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 45 (2), pp. 1479-1520 : 1509-1512

Micrillus suturalis ( CAMERON 1930) , nov.comb. ( Figs 48-55 , Map 3 )

Scimbalium [sic] suturale CAMERON 1930: 155 .

Scimbalium javanicum CAMERON 1936b: 53 f.; nov.syn.

Scimbalium (Schatzmayria) borneense CAMERON 1941: 230 ; nov.syn.

Type material examined S. suturale : Holotype: " Malay Penin., Kedah, Alor Star, / March 30th 1928. / Scimbalium suturale Cam. Type / Type / M. Cameron. Bequest. B.M. 1955-147. / Holotypus Scymbalium suturale Cameron , rev. V. Assing 2013 / Micrillus suturalis (Cameron) , det. V. Assing 2013" ( BMNH).

S. javanicum : Holotype: "F. C. Drescher, Preanger, Bandoeng [today Bandung] Dago, 22.III.1929 / Java: F.C. Drescher, B.M. 1934.-264. / Scimbalium javanicum Cam. Type / Type / Holotypus Scymbalium javanicum Cameron , rev. V. Assing 2013/ Micrillus suturalis (Cameron) , det. V. Assing 2013" ( BMNH).

S. borneense : Holotype: "Pontianak, Borneo / S. borneense Cam. Type / Type / M. Cameron. Bequest. B.M. 1955-147. / Holotypus Scymbalium borneense Cameron , rev. V. Assing 2013 / Micrillus suturalis (Cameron) , det. V. Assing 2013" ( BMNH).

Additional material examined: Thailand: 1, Bangkok (BMNH).

Comment: The original description of Scymbalium suturale is based on a unique holotype from "Malay Peninsula. Kedah; Alor Star" ( CAMERON 1930). The specimen, unfortunately a female in rather poor condition, was located in the Cameron collection at the BMNH.

The original description of S. javanicum is based on a unique holotype from "Bandoeng Dago, Preanger" (Java) ( CAMERON 1936b), that of S. borneense on a unique holotype from "W. Borneo: Pontianak" ( CAMERON 1941). Both holotypes were located in the Cameron collection at the BMNH. In the description of S. borneense, CAMERON (1941) compares the species with Scymbalium suturale CAMERON 1930 from Malaysia, but there is no reference to S. javanicum . An examination of the type material, however, revealed that both holotypes are undoubtedly conspecific; the male primary and secondary sexual characters are identical ( Figs 52-55 ), and no significant external differences were found either.

The types of S. javanicum and S. borneense are distinguished from the holotype of S. suturale only by the more pronounced microsculpture on the pronotum. However, the additional specimen seen from Thailand is intermediate in this respect. Since no additional evidence was found suggesting that S. javanicum represents a distinct species, both S. javanicum and S. borneense are placed in synonymy with S. suturale . Based on the undilated protarsomeres I-IV, S. suturale is moved to Micrillus .

Redescription: Body length 6.5-7.0 mm, length of forebody 3.5-3.6 mm. Habitus as in Fig. 48 . Coloration: head blackish; pronotum and elytra dark-brown to blackish-brown, except for the narrowly and indistinctly dark-reddish posterior margins and suture of the elytra; abdomen blackish, with the paratergites, the posterior margins of segments III-VI, the posterior portion of segment VII, and segments VIII-X dark-reddish; legs and antennae pale reddish-brown.

Head ( Figs 49-50 ) approximately 1.1 times as long as broad and with subparallel lateral margins; posterior angles moderately marked; punctation extremely fine, sparse, and barely noticeable in median dorsal portion, dense and more distinct in posterior and lateral portions; interstices with shallow microsculpture. Eyes slightly more than half the length of postocular region in dorsal view. Antennae slender, approximately 3 mm long; antennomeres IV-XI distinctly oblong; antennomere X approximately 1.5 times as long as broad.

Pronotum ( Figs 49-50 ) 1.11-1.14 times as long as broad and 1.05-1.09 times as broad as head; general shape rather variable: widest near anterior angles and converging posteriad from anterior fourth or with subparallel lateral margins in anterior half (dorsal view); posterior margin weakly to distinctly concave; punctation fine and very dense; interstices with microsculpture.

Elytra ( Figs 49-50 ) 0.91-0.94 times as long as pronotum; surface matt and with microsculpture; punctation extremely fine and dense. Hind wings fully developed. Metatarsomere I longer than the combined length of II and III, but at least slightly shorter than the combined length of II-IV. Protarsomeres I-IV not distinctly dilated.

Abdomen narrower than elytra; punctation dense and rather fine; anterior tergites with distinct, posterior tergites with shallow to indistinct microsculpture; posterior margin of tergite VII with palisade fringe.

: sternite VIII ( Fig. 51 ) strongly oblong, posterior excision broad and moderately deep; aedeagus ( Figs 52-55 ) approximately 1.3 mm long, slender, distinctly asymmetric, and with conspicuously shaped spines in internal sac.

Comparative notes: This species is readily distinguished from other Micrillus species known from the Oriental region by distinctly larger body size, darker coloration, and by the completely different morphology of the aedeagus (much larger, more slender, internal sac with series of strongly sclerotized spines).

Distribution and natural history: Micrillus suturalis is apparently widespread, but not common in the Oriental region. It is currently known from Java, Borneo, Peninsular Malaysia, and Thailand ( Map 4 ).

Figures

Map 3: Distributions of Micrillus indicus (EPPELSHEIM) (triangles), M. nigriceps (CAMERON) (diamonds), M. intermedius (CAMERON) (open and filled circles), and M. siamensis nov.sp. (filled circle) in the Oriental region, based on examined records.

Map 4: Distributions of Micrillus distortus nov.sp. (triangles) and M. suturalis (CAMERON) (circles) in the Oriental region, based on examined records.

Figs 48-55: Micrillus suturalis (CAMERON) (holotypes of Scymbalium borneense CAMERON (48- 49, 51, 54-55) and S. javanicum CAMERON (50-53)): (48) habitus; (49-50) forebody; (51) male sternite VIII; (52-55) aedeagus in lateral and in ventral view. Scale bars: 48-50: 1.0 mm; 51-55: 0.5 mm.