Aenictoxenides Maruyama, 2014

Maruyama, Munetoshi, Komatsu, Takashi, Katayama, Yuji, Song, Xiao-Bin & Sakchoowong, Watana, 2014, Myrmecophilous rove beetles (Coleoptera: Staphylinidae) associated with Aenictus hodgsoni (Hymenoptera: Formicidae) from Thailand, with description of two new genera and three new species, Zootaxa 3796 (2), pp. 361-373 : 369-372

Aenictoxenides Maruyama , gen. n.

( Figs. 33–52 )

Type species: Aenictoxenides mirabilis Maruyama , sp. n. Description. Body ( Figs. 33–35 ) foliaceous, flattened, glossy.

Head ( Figs. 33–36 ) semicircular, strongly flattened above; frons protruded anteriad and laterad to form “arcade” which conceals eyes, mouthparts, bases of antennae underside of head; temples projected laterad, pointed at apex; eyes rather large, located laterally, underside of head; antennae ( Figs. 33–35 , 37 ) 7-segmented, inserted near mouthparts; segment I large, thin, concealed in antennal cavity; segments II–VII connected closely, fusiform overall.

Mouthparts: Labrum ( Fig. 38 ) rather generalized, with some pseudopores, and a row of 3 campaniform sensilla around antero-lateral corner (Fig, 38: arrow). Mandibles ( Fig. 39 ) almost symmetric, with 2 setae around middle of outer margin. Mentum ( Fig. 40 ) sub-trapezoidal, but lateral margin rounded, truncate on anterior margin, sparsely with pseudopores, some setae around antero-lateral area. Labium ( Fig. 41 ): apodeme with lateral lobe short, narrowed toward pointed apex, with apically truncate medial projection; prementum with 2 real pores and 1 setal pore antero-laterally; palpus with segment I long, 3 times as long as II; segment III narrow, elongate; maxilla ( Fig. 42 ) with cardo elongate; lacinia with 4 spines near apex, densely with pubescence; galea short, with tuft of long pubescence at apex; palpus sparsely with pseudopores; segment IV narrowed.

Pronotum ( Figs. 33–35 , 43 ) transverse, with a row of thick setae on lateral margin; hypomera laterally not visible, with several macrosetae; prosternite ( Fig. 20 ) trapezoidal, carinate at midline.

Mesoventrite ( Fig. 44 ) with process not differentiated from that of metaventrite; mesocoxal cavity well margined, clearly separated. Elytra ( Fig. 45 ) transverse, slightly convex above, with a row of thick setae on lateral margin; hypomera laterally not visible, with several macrosetae along lateral margins; hind wings developed.

Legs ( Figs. 34–35 , 46–48 ) short, compressed, with inner margins of femora sulcate to hold tibia; tarsal formula 4–4–5; fore leg ( Fig. 46 ) with tibia slender widest at middle; tarsal segments I–III subequal in length; mid leg ( Fig. 47 ) with coxa oval; tibia thick, widest around basal 1/3; tarsal segments I–III subequal in length; hind leg ( Fig. 48 ) with coxa transverse, with thick setae around lateral area; tibia thick, widest around basal 1/3; tarsal segments I–III subequal in length; segment IV smallest.

Abdomen ( Figs. 33–35 ) widest at segment IV, gently narrowed toward apex; tergite VIII ( Fig. 49 ) narrowed apicad, sub-parallel near apex, rounded on apical margin; sternite ( Fig. 50 ) gently narrowed apicad, rounded at apex; tergites IX and X ( Fig. 51 ) cylindrical; tergite IX narrowed around base; sclerite at base of tergite IX well developed, transverse ( Fig. 51 : arrow); tergite X emarginate on anterior margin in dorsal view.

Male: median lobe of aedeagus ( Fig. 52 ) bulbous at base; apical lobe elongate, pointed at apex; paramere ( Fig. 53 ) with apical lobe elongate.

Female: spermatheca ( Fig. 32 ) coiled around base, with apical part spherical.

Differential diagnosis. This genus is closely related to Aenictoxenus Seevers, 1953 in numerous character states, especially those of the mouthparts and thorax, but distinguished from it by the temples which widen behind the eyes, forming acute posterior head angles (although Aenictoxenus has an “arcade” formed by a fronto-lateral expansion of the head, the temples are not expanded, and instead narrow smoothly and roundly to the head base), the antennae which are 7-segmented (in Aenictoxenus , 8-segmented), the sub-trapezoidal mentum (in Aenictoxenus , the anterior margin is rounded), and tergite X more shallowly emarginate on the anterior margin in dorsal view (in Aenictoxenus , it is deeply emarginate, deeper than 1/2 of the length of tergite X).

Etymology. A combination of the related genus name Aenictoxenus , and the Latin suffix oides (meaning "similar"), indicating a similar genus of Aenictoxenus . Gender masculine.

Distribution. Central Thailand.

Systematic notes. Tribal affiliations of Aenictoxenus are controversial. Jacobson & Kistner (1975) stated the genus does not belong to Pygostenini . However, the related genus Aenictoxenides shares a sclerite at the base of the tergite IX which is one of autapomorphies of Pygostenini (Maruyama et al., in prep.), and the well-sclerotized, cylindrical abdominal segments IX + X are also characteristic in Pygostenini . Although Aenictoxenus does not share the sclerite at base of tergite X, it could be a secondary loss of the state due to extreme miniaturization of the body. This sclerite is ill-defined also in some other minute-sized pygostenines. We propose that both Aenictoxenus and Aenictoxenides are members of Pygostenini .

Figures

FIGURES 33–35. Habitus of Aenictoxenides mirabilis Maruyama, gen. & sp. n. 33―dorsal view; 34―ventral view; 35―lateral view.

FIGURES 36–46. Body parts of Aenictoxenides mirabilis Maruyama, gen. & sp. n. 36―head, dorsal view; 37―left antenna; 38―labrum; 39―left mandible; 40―memtum; 41―labium; 42, right maxilla; 43―pronotum, ventral view; 44―meso- and meta traces; 45―right elytra; 46―left fore leg.

FIGURES 47–54. Body parts of Aenictoxenides mirabilis Maruyama, gen. & sp. n. 47―left mid leg; 48―left hind leg; 49―male tergite VIII; 50―male sternite VIII; 51―male abdominal tergites IX and X; 52―median lobe of aedeagus, lateral view; 53―paramere; 54―spermatheca.

FIGURES 13–23. Body parts of Aenictosymbia cornuta Maruyama, gen. & sp. n. 13―head, dorsal view; 14―labrum (right, epipharynx); 15―left mandible; 16―memtum; 17―labium; 18, right maxilla; 19―pronotum, dorsal view; 20―ditto, ventral view; 21―meso- and meta traces; 22―right elytra; 23―left fore leg.

FIGURES 24–32. Body parts of Aenictosymbia cornuta Maruyama, gen. & sp. n. 24―left mid leg; 25―left hind leg; 26―male tergite VIII; 27―male sternite VIII; 28―male abdominal tergites IX and X; 29―median lobe of aedeagus, lateral view; 30―ditto, apical part, ventra view; 31―paramere; 32―spermatheca.