Drepanomastax Ashe, 2005

Ashe, James S., 2005, Three new genera and four new species of aleocharine staphylinids with unusually long mandibles from Australia (Coleoptera: Staphylinidae: Aleocharinae: Homalotini), Zootaxa 1002 (1), pp. 21-44 : 28-29

Drepanomastax Ashe , new genus

( Figs. 3 , 25–37 )

Type Species. Drepanomastax splendida Ashe , here designated.

Diagnosis. This genus can be easily recognized by the combination of: 4­4­5 tarsal segmentation; the extremely long mandibles with greatly reduced prostheca, and internal edge of molar area slightly to greatly enlarged as triangular blade­like structures ( Fig. 27 ); the transverse, rounded labrum with greatly reduced setation, without extremely long and whip­like setae ( Fig. 25 ); presence of pair of very elongate whip­like setae on the apical margin of the clypeus; the distinctive labium ( Fig. 29 ), with elongate, bifid ligula, incised at apex to near middle into 2 elongate apically rounded or pointed lobes; 1 discal setae, and narrow medial pseudopore field with only a few pseudopores near base; elongate antenna ( Fig. 31 ) with antennomeres 4–8 or 4–10 very elongate to elongate; head subquadrate to slightly transverse, broadest across eyes, sides broadly convergent from eyes to base when viewed in dorsal aspect; and, the very glossy integuments with inconspicuous punctation and widely dispersed setae on the head and pronotum.

Description. Body ( Fig. 3 ) generalized, slender, more­or­less parallel­sided, moderately flattened. Length 3.2–3.6 mm (known species). Vestiture fine and inconspicuous in most, consisting of widely dispersed, very fine, yellowish microsetae, punctures on head and pronotum minute to extremely minute and inconspicuous, larger on elytra and in transverse basal impressions of abdominal terga; without conspicuous microsculpture, body very glossy. Head slightly transverse, 1.1 times as wide as long (width measurement taken immediately behind eyes), head broadest across eyes, sides convergent from eyes to base when viewed in dorsal aspect; eyes moderate sized, length in dorsal aspect about 0.6 times length of temples behind eye; temples broadly convergent behind eyes to base of head in dorsal aspect; neck absent; infraorbital carina present, complete, moderately well developed; antennal fossae very near antero­lateral margins of clypeus, separated by lateral margins by less than 1/5 width of fossa. Clypeus very broad, with elongate whip­like seta on each side of midline. Antenna ( Fig. 31 ) relatively long; known species with article 4 very elongate, 5–8 or 5–9 very elongate to elongate, 10 elongate to slightly transverse, 11 about as long as 9–10 together.

Labrum ( Fig. 25 ) transverse, broadly curved apically, separated from anterior margin of mentum by broad membranous area; setation reduced, without pair of long whip­like setae. Anterior margin of clypeus with very elongate, whip­like seta on each side of midline. Epipharynx as in Fig. 26 . Mandibles ( Fig. 27 ) with very long, curved and slender apices; right and left similar except right with very slight lobe in position of medial tooth; prostheca greatly reduced to a small papillate structure; molar region of internal base of mandible slightly to greatly enlarged into triangularly pointed blades. Maxilla ( Fig. 28 ) similar to Eumecognathus except galea subequal in length to lacinia in repose, and membranous apical lobe of galea more narrow, also inner face of lacinia with spines and spi­ nose setae more densely arranged; maxillary palpi 4­articled, similar to that of Eumecognathus except article 3 broader and more robust, broadest before apex; article 4 very short, length less than width of article 3 at apex. Labium as in Fig. 29 ; ligula bifid, incised at apex to near middle into 2 elongate apically rounded lobes, slender, abut 2/3 length of labial palpus 1; 1 discal seta present medially; medial pseudopore field narrow, with a few pseudopores near base; lateral pseudopore fields each with setose pore, 2 real pores, and about 18–20 pseudopores. Labial palpi 3­articled, first article long, subequal in length to next 2 together, article 2 and 3 subequal in length, without 2 leaf­like sensory appendages apically. Mentum as in Fig. 30 .

Pronotum transverse to subquadrate, up to 1.4 times as wide as long in known species; microsetation very sparse, short; widely dispersed, without conspicuous macrosetae; microsetae directed posteriorly in midline, posteriorly to postero­laterally in anterior half and laterally in posterior half on each side of midline; integument of known species without microsculpture, surface glossy. Hypomera broadly visible in lateral aspect. Elytra 1.2 times length of prothorax; postero­lateral margins sinuate. Meso­ and metasternum as in Fig. 32 ; mesosternum carinate medially at base, carina fading before reaching mesosternal process; mesocoxal cavities fully margined behind; mesosternal process long, slender, pointed apically, extended beyond middle of mesocoxal cavities; metasternal process moderately long, broadly rounded, not attaining mesosternal process, isthmus short; known species with mesosternal process: isthmus: metasternal process in ratio of 4:1:2. Tarsal segmentation 4­4­5.

Abdomen parallel­sided, rounded apically. Known species with abdominal terga III– IV with deep, V with moderate and VI with shallow basal transverse impressions; impressions with large, irregular punctures, without microsetae. Microsetae sparsely distributed. Integument without microsculpture, surface glossy.

Secondary sexual features: None obvious except males with anterior half of sternum VII with densely arranged micropores.

Etymology. The genus name is a combination of the Greek noun “drepane” (feminine) meaning “sickle” or “scimitar” and the Greek noun “mastax” (feminine) meaning “jaws” or “mouth” ( Brown 1956). It refers to the long sickle­shaped mandibles that characterize this genus. Gender: feminine.

Figures

FIGURE 3. Drepanomastax splendida Ashe, habitus dorsal, length, 3.2 mm.

FIGURES 25–29. Drepanomastax splendida Ashe. 25, labrum, dorsal aspect. 26, epipharynx. 27, right and left mandibles respectively, ventral aspect. 28, left maxilla, ventral aspect. 29, labium, ventral aspect. Scale bar = 0.1 mm.

FIGURES 30–34. Drepanomastax splendida Ashe. 30, mentum. 31, antenna. 32, meso­ and metasternum. 33, aedeagus, paramere. 34, aedaegus, median lobe. Scale bar = 0.1 mm.

FIGURES 35–37. Drepanomastax nitida Ashe. 35, spermatheca. 36, aedeagus, paramere. 37, aedaegus, median lobe. Scale bar = 0.1 mm.