Discoxenus Wasmann

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 : 202-204

publication ID	https://doi.org/ 10.11646/zootaxa.4044.2.2
publication LSID	lsid:zoobank.org:pub:7000893A-A8BC-4196-B76D-385C97B96FBD
DOI	https://doi.org/10.5281/zenodo.6111769
persistent identifier	https://treatment.plazi.org/id/0395F739-FFA4-BF26-FF02-1900FEB9BDC8
treatment provided by	Plazi
scientific name	Discoxenus Wasmann
status

Treatment

Genus Discoxenus Wasmann View in CoL

Type species: D. assmuthi Wasmann, 1904 .

Discoxenus Wasmann, 1904: 655 View in CoL ; Seevers 1957: 264; Kistner, 1982: 165.

Diagnosis. This genus is distinguished from other genera in Compactopediina by a combination of following characters (states): body shape limuloid with abdomen gradually narrowed posteriorly, head completely covered by pronotum, antennae fusiform, antennal segment II small, petioles completely covered with antennal segments III– X, maxillary basistipes fused with palpifer partly or completely, tarsal formula 4-4-5.

Redescription. Body glossy, overall orange brown, antennae and elytra slightly darker ( Figs. 1–18 View FIGURES 1 – 4 View FIGURES 5 – 12 View FIGURES 13 – 18 , 165, 166 View FIGURES 165 – 166 ). Head capsule ( Figs. 19 View FIGURES 19 – 37 , 38 View FIGURES 38 – 53 , 54 View FIGURES 54 – 72 , 73 View FIGURES 73 – 88 , 89 View FIGURES 89 – 104 , 105 View FIGURES 105 – 120 , 121 View FIGURES 121 – 136 , 137 View FIGURES 137 – 148 , 149 View FIGURES 149 – 164 ) transverse, widest at eyes, sparsely covered with minute pores, completely covered by pronotum in dorsal view, several setae present at postgenae and anterior margin of clypeus; antennal shelf well developed, formed by anteriorly produced epicranium and clypeus, covered with several setae and pores; occipital suture absent. Eyes well developed. Gula short, strongly dilated posteriorly, fused to submentum. Antennae ( Figs. 20 View FIGURES 19 – 37 , 39 View FIGURES 38 – 53 , 55 View FIGURES 54 – 72 , 74 View FIGURES 73 – 88 , 90 View FIGURES 89 – 104 , 106 View FIGURES 105 – 120 , 122 View FIGURES 121 – 136 , 138 View FIGURES 137 – 148 , 150 View FIGURES 149 – 164 ) with 11 segments, fusiform except for segments I and II, widest at segment IV or V; apical margin of each segment fimbriated; segment I long, almost as long as segment XI, with 2 macrosetae; segment II short, narrower than other segments; pedicles invisible externally between segments III–X. Labrum ( Figs. 21 View FIGURES 19 – 37 , 40 View FIGURES 38 – 53 , 56 View FIGURES 54 – 72 , 75 View FIGURES 73 – 88 , 91 View FIGURES 89 – 104 , 107 View FIGURES 105 – 120 , 123 View FIGURES 121 – 136 , 139 View FIGURES 137 – 148 , 151 View FIGURES 149 – 164 , left side) transverse, sparsely covered with pseudopores, with anterior margin concave at middle, 2–4 pairs of large primary setae present on anterior half, a pair of setaceous sensillae and minute sensillae present at middle of anterior margin (probably homologous to a - and b -sensillae of Sawada [1972]). Epipharynx ( Figs. 21 View FIGURES 19 – 37 , 40 View FIGURES 38 – 53 , 56 View FIGURES 54 – 72 , 75 View FIGURES 73 – 88 , 91 View FIGURES 89 – 104 , 107 View FIGURES 105 – 120 , 123 View FIGURES 121 – 136 , 139 View FIGURES 137 – 148 , 151 View FIGURES 149 – 164 , right side) medially covered with few pores. Mandibles ( Figs. 22, 23 View FIGURES 19 – 37 , 41, 42 View FIGURES 38 – 53 , 57, 58 View FIGURES 54 – 72 , 76, 77 View FIGURES 73 – 88 , 92, 93 View FIGURES 89 – 104 , 108, 109 View FIGURES 105 – 120 , 124, 125 View FIGURES 121 – 136 , 140, 141 View FIGURES 137 – 148 , 152, 153 View FIGURES 149 – 164 ) asymmetric. Right mandibles with a small tooth. Maxilla ( Figs. 24 View FIGURES 19 – 37 , 59 View FIGURES 54 – 72 ) with medial sclerite of stipes (basistipes) somewhat fused with outer sclerite of stipes (palpifer), 2 long setae present at base of basistipes; palpus with 5 segments, segments II and III sparsely covered with setae and pores; lacinia with 10 thick setae apically; galea with 4–5 thick and long setae apically. Mentum ( Figs. 25 View FIGURES 19 – 37 , 43 View FIGURES 38 – 53 , 60 View FIGURES 54 – 72 , 78 View FIGURES 73 – 88 , 94 View FIGURES 89 – 104 , 110 View FIGURES 105 – 120 , 126 View FIGURES 121 – 136 , 142 View FIGURES 137 – 148 , 154 View FIGURES 149 – 164 ) distinct from submentum, with anterior margin submembranous, difficult to discriminate from membrane connected to labium, with lateral margin rounded, 2 pairs of long setae and a pair of short setae present at anterolateral corners. Prementum ( Figs. 26 View FIGURES 19 – 37 , 61 View FIGURES 54 – 72 ) with a pair of distal setae at anterior margin, a pair of setal pores present on posteromedial area; palpus with 4 segments; segment I with 2–3 setae; segment II with 5 setae on anterior half, aboral one seta longer than other setae.

Pronotum ( Figs. 27 View FIGURES 19 – 37 , 44 View FIGURES 38 – 53 , 62 View FIGURES 54 – 72 , 79 View FIGURES 73 – 88 , 95 View FIGURES 89 – 104 , 111 View FIGURES 105 – 120 , 127 View FIGURES 121 – 136 , 143 View FIGURES 137 – 148 , 155 View FIGURES 149 – 164 ) semicircular, dorsally convex, sparsely covered with minute pores. Elytron ( Figs. 28 View FIGURES 19 – 37 , 45 View FIGURES 38 – 53 , 63 View FIGURES 54 – 72 , 80 View FIGURES 73 – 88 , 96 View FIGURES 89 – 104 , 112 View FIGURES 105 – 120 , 128 View FIGURES 121 – 136 , 144 View FIGURES 137 – 148 , 156 View FIGURES 149 – 164 ) with posterior margin subtransparent, 4 long macrosetae present at outer lateral margin. Prosternum short, carinate at middle. Wings fully developed. Mesoventrite ( Figs. 29 View FIGURES 19 – 37 , 64 View FIGURES 54 – 72 ) medially covered with short setae, approximately half as long as metaventrite; mesoventral intercoxal process narrow, acutely developed posteriorly, fused with metaventral process. Metaventrite ( Figs. 29 View FIGURES 19 – 37 , 64 View FIGURES 54 – 72 ) sparsely covered with yellow setae and pores except for mesocoxal cavities, 2 pairs of macrosetae present at middle except for D. cambodiensis without macrosetae. Mesocoxal cavity completely margined. Legs short and flat, sparsely covered with setae. Fore coxa with a macroseta around apex; tibia with inner margin densely covered with setae, with 2–5 thick setae and 2 spurs at apex. Mid trochanter with a macroseta at middle; femur with 1–2 macrosetae at base and apex; tibia with apical half of inner margin densely covered with setae, 2–3 macrosetae present at outer margin, with 2–5 thick setae and 2 spurs at apex. Hind coxa with 1–2 macrosetae around inner margin; trochanter with a macrosetae at middle; femur with 1–2 macrosetae at base and apex; tibia with 2–3 macrosetae at outer margin, 2–6 thick setae and 2–3 spurs present at apex; tarsal segment I densely covered with yellow setae on inner margin. Tarsal formula 4-4-5.

Abdomen ( Figs. 1–18 View FIGURES 1 – 4 View FIGURES 5 – 12 View FIGURES 13 – 18 ) narrowed posteriorly. Sternites sparsely covered with yellow setae and macrosetae. Tergite IX ( Figs. 33 View FIGURES 19 – 37 , 49 View FIGURES 38 – 53 , 68 View FIGURES 54 – 72 , 84 View FIGURES 73 – 88 , 100 View FIGURES 89 – 104 , 116 View FIGURES 105 – 120 , 132 View FIGURES 121 – 136 , 147 View FIGURES 137 – 148 , 160 View FIGURES 149 – 164 ) fully subdivided by tergite X, with 5 pairs of macrosetae on posterior half. Tergite X with 3 pairs of macrosetae around posterior margin. Macrochaetotaxy varied in species.

Male. Median lobe of aedeagus ( Figs. 34, 35 View FIGURES 19 – 37 , 50, 51 View FIGURES 38 – 53 , 69, 70 View FIGURES 54 – 72 , 85, 86 View FIGURES 73 – 88 , 101, 102 View FIGURES 89 – 104 , 117, 118 View FIGURES 105 – 120 , 133, 134 View FIGURES 121 – 136 , 161, 162 View FIGURES 149 – 164 ) with basal capsule longer or as well as apical lobe; distal crest distinct, strongly developed in the assmuthi species group; copulatory piece long, longer or as long as apical lobe. Paramere ( Figs. 36 View FIGURES 19 – 37 , 52 View FIGURES 38 – 53 , 71 View FIGURES 54 – 72 , 87 View FIGURES 73 – 88 , 103 View FIGURES 89 – 104 , 119 View FIGURES 105 – 120 , 135 View FIGURES 121 – 136 , 163 View FIGURES 149 – 164 ) with paramerite covered with several pores at middle; condylite narrow, distinct from paramerite, covered with pores basally; velar sac sclerite (inner surface of paramerite) with 3–6 setae; apical lobe approximately on third as long as paramerite, sparsely covered with pores, several minute setae present.

Comments. Morphological characters of small body parts such as mouthparts are important features in Aleocharinae systematics ( Sawada 1972). In this paper, we describe such characters observed in all the Cambodian species under study.