Chimaerocyon shimadai, Fikáček, Martin, Maruyama, Munetoshi, Vondráček, Dominik & Short, Andrew E. Z., 2013

Fikáček, Martin, Maruyama, Munetoshi, Vondráček, Dominik & Short, Andrew E. Z., 2013, Chimaerocyon gen. nov., a morphologically aberrant myrmecophilous genus of water scavenger beetle (Coleoptera: Hydrophilidae: Sphaeridiinae), Zootaxa 3716 (2), pp. 277-288 : 282-285

Chimaerocyon shimadai sp. nov.

( Figs. 1–3 , 6–13 , 15–21 , 23–26, 28–30 )

Type material. Holotype: male (KUZC): MALAYSIA: Pahang / Bukit Fraser (1250 m), / 25.IV.2011 / SHIMADA Taku. Paratypes: 2 males, 1 female (KUZC, NMPC): same label data as the holotype.

DNA isolate and sequences of the holotype. The DNA isolate of the holotype is deposited in NMPC. Sequence data were submitted into GenBank under the following accession numbers: cox1 — KF623548 ; cox2 — KF623549 ; 18S — KF623550 ; 28S — KF623551 .

Description. Body length 2.6–2.9 mm (2.7 mm in holotype), body width 1.9–2.2 mm (2.0 mm in holotype). Body widest at anterior margin of elytra, strongly narrowing posteriad; elytra slightly roof-like in anterior view. Coloration black with widely reddish margins of clypeus, elytra and lateral and sutural margins of elytra; ventral surface and appendages reddish brown. Head with dense punctation consisting of crescent-like to semicircular punctures, without microsculpture on interstices; punctation on pronotum and elytra as dense as that on head, consisting of slightly finer punctures; pronotal punctures transverse, scar-like, elytral punctures dot-like. Eyes divided by 7.5× the width of one eye in dorsal view. Mentum with sparse moderately strong punctation. Elytron with remnants of four or five striae posteromesally situated in deep depression; lateral portion of elytra widely explanate. Mesoventral plate rhomboid, slightly longer than wide, with slightly concave margins. Median portion of metaventrite with fine but dense punctation bearing enlarged setae posteromesally in male, uniformly pubescent in female. Abdominal ventrites with dense and rather coarse setiferous punctation, bearing longer and slightly denser pubescence around apical emargination in both sexes. Abdominal ventrite 5 widely emarginate apically with posterior margin of emargination irregularly convex in male, narrowly and simply emarginate in female. Metatarsus extremely short, with metatarsomere 1 ca. 1.5× as long as tarsomere 2. Male sternite 9 with numerous stout setae apically. Aedeagus 1.3 mm long, phallobase ca. 0.5× as long as paramere, strongly asymmetrical; paramere weakly narrowing from base to apical fourth, membranous, flat and slightly expanded apically, without apical setae.

Diagnosis. Chimaerocyon shimadai sp. nov. may be distinguished from C. sumatranus sp. nov. by the combination of the following characters: (1) the dorsal surface is piceous with widely reddish margins of elytra, pronotum and clypeus ( Figs. 1–3 ) (dorsal surface is uniformly reddish in C. sumatranus , Figs. 4–5 ); (2) elytra highly arched, forming a pointed arch in anterior view ( Fig. 3 ) (elytra widely rounded in anterior view in C. sumatranus , Fig. 5 ); (3) the emargination of abdominal ventrite 5 sexually dimorphic in shape, wide and subrectangular in male, narrowly semicircular in female ( Figs. 12–13 ) (widely bisinuate in female in C. sumatranus ( Fig. 14 ), male is unknown for the latter species); (4) both sexes with longer setae around apical emargination of abdominal ventrite 5 ( Figs. 12–13 ) (without such setae in C. sumatranus , Fig. 14 ); (5) mesoventral plate as long as wide or only slightly longer, rhomboid in shape (ca. 1.4× longer than wide, with strongly concave sides in C. sumatranus ). Besides these characters, there are also slight differences in the number of impressed series at the elytral apex (4–5 series in C. shimadai , 5 series in C. sumatranus ; Figs. 26–27 ) and in the character of the punctation of the mentum ( Figs. 19, 22 ) and the metaventrite (moderately coarse in C. shimadai , consisting of fine punctures in C. sumatranus ), but it is not clear at present to what extent these characters are intraspecifically variable due to the low number of specimens examined. We expect that both species also differ in the morphology of the aedeagus and the shape of the apical emargination of male abdominal ventrite 5, but this may be only confirmed once the male of C. sumatranus is discovered.

Etymology. The species is dedicated to Mr. Taku Shimada, the collector of the type series.

Biology. The beetles were collected from a brood cell of a nest of Pheidole singaporensis Özdikmen, 2010 (replacement name for Pheidole longipes (Smith, 1857)) . The nest was in a cliff along a forest trail in Bukit Fraser.

The only female available had a single egg ( Fig. 7 ) with completely developed chorion in its abdomen, measuring 0.85×0.35 mm and hence occupying a large part of the internal abdominal volume.

Distribution. Known only from the type locality in Peninsular Malaysia.

Figures

FIGURES 1 – 5. Habitus of Chimaerocyon species. 1 – 3 — male paratype of Chimaerocyon shimadai (1 — dorsal view, 2 — lateral view, 3 — frontal view). 4 – 5 — holotype of C. sumatranus (4 — dorsal view, 5 — frontal view).

FIGURES 6 – 14. Morphological details of Chimaerocyon shimadai (6 – 13) and C. sumatranus (14). 6 — ventral view, 7 — egg drawn to scale with Fig. 6, 8 — aedeagus of the holotype, 9 — male sternite 8 of the holotype, 10 — male sternite 9, 11 — hind wing of the holotype, 12 – 14 — abdominal apex (12 — male holotype of C. shimadai, 13 — female paratype of C. shimadai, 14 — female holotype of C. sumatranus). Abbreviations (numbers refer to characters in Fig. 32): msuc — male suckers on maxilla, elpr — elevated median portion of prosternum, wepi — wide epipleuron posteriorly, shtars — shortened tarsus, abdem — abdominal emargination.

FIGURES 15 – 22. Detailed morphology of Chimaerocyon shimadai (15 – 21) and C. sumatranus (22). 15 — head in dorsal view, 16 — head in ventral view, 17 — prothorax and head in ventral view, 18 — clypeus in lateral view, 19, 22 — mentum, 20 — profurca, 21 — elevated mesal portion of prosternum. Abbreviations (numbers refer to those used in Fig. 32): cly — clypeus, msuc — male sucker on maxilla.

FIGURES 23 – 30. Detailed morphology of Chimaerocyon shimadai (23 – 26, 28 – 30) and C. sumatranus (27). 23 — meso- and metathorax in ventral view, 24 — mesoventrite in lateral view, 26 — median portions of meso- and metaventrite in ventral view, 26 – 27 — right elytral apex, 28 — metatarsus, 29 — metatarsal claws, 30 — detail of apical portion of elytral series 1 – 2.