Discoxenus hirsutus, 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 : 213-214

Discoxenus hirsutus n. sp.

( Figs. 9, 10 , 89–104 )

Type materials. Holotype: ♂, 500 m S of Ankor Wat, Siem Reap, Cambodia, 5 VI 2012, Maruyama M. (Colony no. MMCB-T-2012-1-002).

Paratypes: Cambodia: 4♂♂, 16♀♀, same as holotype (1♂, completely dissected, 1♂, abdominal segments VIII–X dissected off). 6♂♂, North Wall of Preah Khan, Siem Reap, 19 VIII 2012, Maruyama M. leg. (Colony no. MMCB-T-2012-2-005) (1♂, completely dissected). 1♀, 1 km W of Banteay Prei, Siem Reap, 21 VIII 2012, Maruyama M. leg. (Colony no. MMCB-T-2012-2-0017) (abdominal segments VIII–X dissected off). 2♂♂, 1♀, Ankor Thom, Siem Reap, 12 XII 2012, Kanao T. leg. (Colony no. KT433) (1♂, completely dissected). 1♂, 2♀♀, 0.76 km NE of Preah Kham, Siem Reap, 18 VIII 2014, Kakizoe S. & Maruyama M. leg. (Colony no. SK002). 1♀, same locality data to SK002, 19 VIII 2014, Kakizoe S. leg. (Colony no. SK007).

Diagnosis. This species is easily distinguished from other Discoxenus species by a combination of the following two character states: the macrochaetotaxy of tergites III–VIII (6, 6, 6, 6, 6, 6), and sternites VI–VII with two transverse rows of 6–14 macrosetae at middle and posterior margin. This species is most similar to D. phourini , but is distinguishable from it by the elytra with 10 macrosetae on disc ( Fig. 96 ), and spermatheca with shorter basal part which is less than 2 times longer than apical part ( Fig. 104 ).

Description. Head ( Fig. 89 ) approximately 1.3 times wider than long. Antenna ( Figs. 9, 10 , 90 ) with segment I longer than other segments; segment II as long as segment III with 2 macrosetae; segment III dilated apically; segment IV transverse; segment V wider than other segments; segments VI–XI successively narrowed distally; segments VI–VII wider than long; segment VIII subquadrate; segments IX–X longer than wide; segment XI approximately 2 times longer than wide, widest around middle. Labrum ( Fig. 91 , left side) with anterior margin deeply concave at middle; median projection of apodeme produced posteriorly, with apex rounded; 5–6 lateral setae present in ventral view ( Fig. 91 , right side). Mandibles ( Figs. 92, 93 ) covered with 20–30 pores. Left mandible ( Fig. 92 ) with adoral margin moderately pointed around middle. Right mandible ( Fig. 93 ) with a small tooth. Maxillary palpal segment III approximately 2 times longer than wide. Mentum ( Fig. 94 ) approximately 2 times wider than long, covered with around 50 pores. Labium with prementum covered with 12–14 pores.

Pronotum ( Fig. 95 ) sparsely covered with approximately 46 macrosetae, 6 minute setae present around anterior margin. Elytron ( Fig. 96 ) transverse, sparsely covered with several setae at anterolateral outer corner, 10 macrosetae present on disc. Metaventrite approximately 1.5 times as long as mesoventrite.

Tergites III–VI ( Fig. 9 ) almost without yellow setae. Tergite VII with a row of yellow setae subapically. Tergite VIII ( Fig. 97 ) with posterior margin pointed, 3 pairs of macrosetae present at posterior margin, 2 pairs of macrosetae present around middle. Macrochaetotaxy of abdominal tergites III–VIII = 6, 6, 6, 6, 6, 6. Sternite III ( Fig. 10 ) with posterior half densely covered with setae. Sternites IV–VIII with a row of 4–6 yellow setae at middle. Sternites III–VII with 6–10 macrosetae at posterior margin, a row of 10–16 macrosetae present at middle.

Male. Sternite VIII ( Fig. 98 ) with 4 pairs of macrosetae around posterior margin and middle, respectively. Median lobe of aedeagus moderately narrowed towards apical lobe in ventral view ( Fig. 101 ); basal capsule with distal crest rounded apically ( Fig. 102 ); apical lobe less than half as wide as basal capsule in lateral view ( Fig. 102 ). Paramere ( Fig. 103 ) with paramerite more than 3 times wider than condylite; velar sac sclerite with 5–6 setae; apical lobe with 2–4 minute setae at apex.

Female. Sternite VIII ( Fig. 99 ) with 3 pairs of macrosetae at posterior margin, 11–12 macrosetae present around middle. Spermatheca ( Fig. 104 ) with basal part less than 2 times longer than apical part.

Measurement. Body length = average 1.68 mm (1.55–1.70 mm, N = 10), pronotal length = average 0.60 mm (0.58–0.63 mm, N = 10), pronotal width = average 0.84 mm (0.80–0.87 mm, N = 10), elytral length = average 0.43 mm (0.41–0.44 mm, N = 10), elytral width = average 0.47 mm (0.46–0.51 mm, N = 10).

Etymology. The specific epithet hirsutus is a Latin adjective meaning “hairy,” in reference to the diagnostic number of macrosetae on the abdominal sternites.

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

Comments. A total of ten specimens of D. hirsutus were found in three colonies of H. makhamensis (colony no. MMCB-T-2012-2-005, MMCB-T-2012-2-017, and KT433) while 21 specimens were found in one nest of H. cf. xenotermitis (MMCB-T-2012-1-002). All these beetles were directly collected from the fungus gardens of the two termite species, and never attacked by their hosts. 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 5 – 12. Habitus. 5 – 6. Discoxenus phourini n. sp.: 5. Dorsal view, 6. Ventral view. 7 – 8. D. kohkongensis n. sp.: 7. Dorsal view, 8. Ventral view. 9 – 10. D. hirsutus n. sp.: 9. Dorsal view, 10. Ventral view. 11 – 12. D. minutus n. sp.: 11. Dorsal view, 12. Ventral view.

FIGURES 89 – 104. Discoxenus hirsutus n. sp.: 89. Head, 90. Antenna, 91. Labrum (left side = dorsal view, right side = ventral view), 92. Mandible, left, 93. Mandible, right, 94. Mentum, 95. Pronotum, 96. Elytron, right, 97. Tergite VIII, 98. Sternite VIII, male, 99. Sternite VIII, female, 100. Tergites IX and X. 101. Median lobe of aedeagus, ventral view, 102. Median lobe of aedeagus, lateral view, 103. Paramere, 104. Spermatheca.