Discoxenus lucidus, Kanao, Taisuke & Maruyama, Munetoshi, 2015

Kanao, Taisuke & Maruyama, Munetoshi, 2015, Eight new species, a new record, and redescription of the genus Discoxenus Wasmann, 1904: The first record of termitophilous rove beetles in Cambodia (Coleoptera: Staphylinidae: Aleocharinae), Zootaxa 4044 (2), pp. 201-223 : 216-218

Discoxenus lucidus n. sp.

( Figs. 13, 14 , 121–136 , 166 )

Type materials. Holotype: ♂, Koh Kong, Cambodia, 7 XII 2012, Kanao T. leg. (Colony no. KT428).

Paratypes: Cambodia: 1♂, 49♀♀, same data as holotype (1♂, 1♀, abdominal segments VIII–X dissected off).

1♀, Ankor Thom, Siem Reap, 17 XII 2012, Kanao T. leg. (Colony no. KT439). 1♀, 5 sex?, 500 m S of Ankor Wat, Siem Reap, 5 VI 2012, Maruyama M. leg. (Colony no. MMCB-T-2012-1-002). 2♂♂, 1♀, 1 km S of Angkor Wat, Siem Reap, 18 VIII 2012, Maruyama M. leg. (Colony no. MMCB-T-2012-2-003). 1♂, 4♀♀, North Wall of Preah Khan, Siem Reap, 19 VIII 2012, Maruyama M. leg. (Colony no. MMCB-T-2012-2-005). 1♂, 1 km W of Banteay Prei, Siem Reap, 21 VIII 2012, Maruyama M. leg. (Colony no. MMCB-T-2012-2-0017) (completely dissected).

Diagnosis. This species is distinct, and is easily distinguishable from other Discoxenus species by a combination of the following two character states: a pronotum without macrosetae on disc ( Fig. 127 ), and macrochaetotaxy of abdominal tergites (4, 4, 4, 4, 4, 6).

Description. Head ( Fig. 121 ) approximately 1.3 times wider than long. Antenna ( Figs. 13, 14 , 122 ) with segment I longer than other segments; segment II shorter than other segments, with 2 macrosetae; segment III trapezoidal; segment IV transverse; segment V wider than other segments; segments VI–XI successively narrowed distally; segment VI subquadrate; segments VII–X longer than wide; segment XI narrow, approximately 3 times longer than wide. Labrum ( Fig. 123 , left side) with anterior margin deeply concave at middle; median projection of apodeme triangular, with apex rounded; 4–5 lateral setae present in ventral view ( Fig. 123 , right side). Mandibles ( Figs. 124, 125 ) covered with 20–30 pores. Left mandible ( Fig. 124 ) with adoral margin moderately pointed around middle. Right mandible ( Fig. 125 ) with a small tooth. Maxillary palpal segment III approximately 2.7 times longer than wide. Mentum ( Fig. 126 ) short, approximately 3.7 times wider than long, covered with around 60 pores. Labium with prementum covered with approximately 20 pores.

Pronotum ( Fig. 127 ) covered with approximately 22 short macrosetae laterally. Elytron ( Fig. 128 ) transverse, sparsely covered with yellow setae, 5 macrosetae present laterally. Metaventrite approximately 1.8 times longer than mesoventrite.

Tergites III–VII ( Fig. 13 ) with 1–2 setae at each lateral margin. Tergite VIII ( Fig. 129 ) with posterior margin pointed, 3 pairs of macrosetae present at posterior margin, with 2 pairs of macrosetae around middle. Macrochaetotaxy of abdominal tergites III–VIII = 4, 4, 4, 4, 4, 6. Sternite III ( Fig. 14 ) with posterior half densely covered with setae. Sternites IV–VI with posterior half sparsely covered with setae. Sternite VII with a row of yellow setae at middle. Sternites III–VII with 6–10 macrosetae at posterior margin.

Male. Sternite VIII ( Fig. 130 ) with 3 pairs of macrosetae at posterior margin, 2 pairs of macrosetae present mediolaterally. Median lobe of aedeagus moderately narrowed apically in ventral view ( Fig. 133 ); basal capsule with distal crest triangular, strongly produced apically in lateral view ( Fig. 134 ); apical lobe less than half as wide as basal capsule in lateral view ( Fig. 134 ). Paramere ( Fig. 135 ) with paramerite broad, approximately 4 times wider than condylite; velar sac sclerite with 5–6 setae; apical lobe with 2 minute setae at apex.

Female. Sternite VIII ( Fig. 131 ) with 2 pairs of macrosetae at posterior margin and middle. Spermatheca ( Fig. 136 ) with basal part as long as apical part.

Measurement. Body length = average 2.67 mm (2.30–2.94 mm, N = 10), pronotal length = average 0.70 mm (0.63–0.75 mm, N = 10), pronotal width = average 0.93 mm (0.87–1.02 mm, N = 10), elytral length = average 0.52 mm (0.48–0.54 mm, N = 10), elytral width = average 0.58 mm (0.54–0.61 mm, N = 10).

Etymology. The specific epithet is derived from the Latin adjective lucidus meaning “lucid,” in reference to the diagnostic glossy and smooth body of this species.

Host species. Hypotermes makhamensis Ahmad, 1965 and H. cf. xenotermitis ( Wasmann, 1896) .

Comments. Six of 65 D. lucidus specimens used in this study were collected form a nest of H. cf. xenotermitis (Colony no. MMCB-T-2012-1-002) while the other 59 specimens were collected from five colonies of H. makhamensis . It is unlikely that the one of these host species may be accidental.

There were no morphological differences between the specimens collected from nests of H. makhamensis and H. cf. xenotermitinis.

Figures

FIGURES 13 – 18. Habitus. 13 – 14. Discoxenus lucidus n. sp.: 13. Dorsal view, 14. Ventral view. 15 – 16. D. kakizoei n. sp.: 15. Dorsal view, 16. Ventral view. 17 – 18. D. katayamai: 17. Dorsal view, 18. Ventral view.

FIGURES 121 – 136. Discoxenus lucidus n. sp.: 121. Head, 122. Antenna, 123. Labrum (left side = dorsal view, right side = ventral view), 124. Mandible, left, 125. Mandible, right, 126. Mentum, 127. Pronotum, 128. Elytron, right, 129. Tergite VIII, 130. Sternite VIII, male, 131. Sternite VIII, female, 132. Tergites IX and X, 133. Median lobe of aedeagus, ventral view, 134. Median lobe of aedeagus, lateral view, 135. Paramere, 136. Spermatheca.

FIGURES 165 – 166. Habitus. 165. Discoxenus kohkongensis n. sp., 166. D. lucidus n. sp.