Mimoscydmus Franz

Jałoszyński, Paweł, 2013, Revision of Neotropical genera Microraphes Franz, Heteroscydmus Franz and Mimoscydmus Franz (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 3722 (2), pp. 245-266 : 255-259

Mimoscydmus Franz

Mimoscydmus Franz, 1980: 220 . Type species: Mimoscydmus brasiliensis Franz, 1980 (orig. des.).

Revised diagnosis. Male: head short, with vertex not expanded dorso-caudad; occipital constriction only slightly narrower than vertex; thick and long bristles absent on head but present on sides of prothorax; fronto-clypeal groove absent; submentum not demarcated laterally from hypostomae by sutures; maxillary palpomere III stout; antennae with distinctly delimited club composed of antennomeres IX–XI; pronotum with indistinct (i.e., not sharp) lateral edges visible in posterior half; base of pronotum with long and deep transverse groove, without pits and without sub-lateral carinae; basisternal part of prosternum much shorter than procoxal cavities; prosternum with intercoxal process developed as a low (i.e., only slightly expanding ventrally) carina not extending to anterior carina of procoxal cavities; prothoracic hypomeral ridges complete; pronotosternal sutures visible only along sides of basisternal part of prosternum; mesoventral intercoxal process long, narrow and moderately strongly expanding ventrally (but not keel-shaped); mesoventrite with asetose lateral impressions behind anterior ridge, without setose impressions; mesothorax with deep ventro-lateral foveae; mesocoxal projection with short and barely discernible posterior lobe; metacoxae narrowly separated by intercoxal process composed of a pair of long spines; each elytron with single rudimentary and asetose basal fovea; aedeagus asymmetrical and with free parameres. Female diagnostic characters unknown.

Redescription. Body of male ( Fig. 3) moderately convex, elongate and slender, with moderately long appendages, BL slightly exceeding 0.6 mm; cuticle glossy, light brown, with strongly and strikingly setose sides of pronotum and finely setose remaining body parts.

Head ( Figs. 3, 13– 14) with anterior part (in front of occipital constriction) about as long as broad, with large eyes; occipital constriction ( Figs. 13–14; occ) only slightly narrower than vertex; tempora ( Fig. 13; tm) short and strongly convergent caudad, without bristles; vertex ( Fig. 13; vt) broader than long, convex, not projecting dorsocaudad but with posterior margin expanding caudad; frons ( Fig. 13; fr) transverse and subtrapezoidal with anterior margin distinctly expanding anterad in middle, posteriorly confluent with vertex; frontoclypeal groove absent; antennal insertions broadly separated.

Labrum transverse with rounded anterior margin. Mandibles ( Figs. 13–14; md) symmetrical, with broad base and slender, curved distal part, mesal tooth developed as rounded expansion; prostheca not visible in transparent mount. Each maxilla ( Fig. 14) with subtriangular basistipes ( Fig. 14; bst), elongate galea ( Fig. 14; gal) and lacinia ( Fig. 14; lac) and moderately long maxillary palp ( Fig. 14; mxp) composed of strongly elongate palpomere I, strongly elongate, pedunculate palpomere II, broad and stout palpomere III broadest in distal third, and small, elongate, subconical and pointed palpomere IV with distinctly delimited apical part.

Labium ( Fig. 14) with transverse submentum ( Fig. 14; smn) not demarcated posteriorly and fused laterally with postcardinal parts of hypostomae; subrectangular mentum ( Fig. 14; mn); and short prementum bearing narrowly separated at bases small 3 -segmented labial palps ( Fig. 14; lp). Hypostomal ridges ( Fig. 14; hr) long and recurved, extending nearly to posterior tentorial pits.

Gular plate ( Fig. 14; gp) large and distinctly narrowing anterad; gular sutures ( Fig. 14; gs) superficial; posterior tentorial pits ( Fig. 14; ptp) small but distinct, located anterior to transverse arcuate impression delimiting ventrally 'neck region' from anterior part of head.

Antennae ( Fig. 3) with indistinctly delimited club composed of antennomeres IX–XI; antennomere VIII distinctly smaller than VII.

Pronotum ( Fig. 3) in dorsal view oval with weakly arcuate anterior and posterior margins and sides rounded in anterior half and slightly concave in posterior third, anterior and posterior corners distinct; marginal carinae developed as fine and blunt edges visible in posterior half of pronotum; sub-lateral carinae absent; base of pronotum with distinct and long transverse groove, without pits; sides of pronotum with dense, thick and long bristles ( Fig. 15).

Prosternum ( Fig. 15) with short basisternal part ( Fig. 15; bst) distinctly demarcated from procoxal cavities ( Fig. 15; pcc) by irregular, serrate carina; median part of sternum with prosternal intercoxal process developed as a short and fine carina not connected with anterior carina of procoxal cavities; procoxal sockets ( Fig. 15; pcs) closed by broad postero-lateral lobes of sternum; hypomera ( Fig. 15; hy) elongate, divided into broad lateral parts and extremely narrow internal (adcoxal) parts, adcoxal parts of hypomera anteriorly fused with prosternum, so that pronotosternal sutures ( Fig. 15; nss) visible only along sides of basisternal parts of prosternum; hypomeral ridges ( Fig. 15; hyr) complete, anteriorly connected to pronotosternal sutures.

Mesonotum very small, approximately heart-shaped, with slightly concave lateral margins of subtriangular mesocutellum barely visible between bases of elytra; mesoscutoscutellar suture absent.

Mesoventrite ( Fig. 16) with broad anterior ridge ( Fig. 16; ar); mesoventral intercoxal process ( Fig. 15; msvp) narrow and moderately expanded ventrally, anteriorly connected with anterior ridge, posterior part of mesoventral intercoxal process with short posterior arms ( Fig. 16; pa); asetose lateral impressions ( Fig. 16; ai) present; mesanepisternum with moderately long prepectus ( Fig. 16; pre) and posterior part largely hidden in ventral view; mesepimeron not visible in ventral view; sides of mesothorax with deep ventro-lateral foveae ( Fig. 16; vlf); mesocoxal projections ( Fig. 16; mcp) with mesocoxal sockets ( Fig. 16; mscs) located on their meso-ventral surface and with small, barely discernible and asetose posterior lobes ( Fig. 16; pl).

Metaventrite ( Fig. 16; vIII) longer than broad, anteriorly fused with mesoventrite, posteriorly shallowly bisinuate and with narrow median metaventral intercoxal process composed of a pair of long spines ( Fig. 16; mtvp). Metanepisterna and metepimera narrow.

Metafurca ( Fig. 16) with elongate stalk and divergent, recurved lateral furcal arms ( Fig. 16; mtfa).

Elytra ( Fig. 3) oval, each with single rudimentary and asetose basal fovea located in shallow basal impression; humeral calli well-marked and developed as longitudinal protuberances; elytral apices unmodified, separately rounded.

Hind wings well-developed, about twice as long as elytra.

Legs ( Figs. 3, 15– 16) moderately long and slender; procoxae subglobose, mesocoxae elongate, metacoxae transverse; all trochanters short; all femora weakly clavate; tibiae short and slightly thickening distally; tarsi short and stout.

Abdominal sternites unmodified, suture between VII and VIII barely marked.

Aedeagus ( Figs. 28–29) symmetrical, lightly sclerotized and thin-walled, parameres present, free and slender, each with two apical setae.

Distribution and composition. Mimoscydmus (as re-defined here) is represented by a single species known from the northern part of Brazil ( Fig. 37).

Remarks. Franz (1980) compared Mimoscydmus to Microscydmus and listed the following differences: the pronotum with fine lateral edges and ante-basal transverse groove; parameres absent; and the basal orifice of the aedeagus located basally. The genital characters were clearly misinterpreted, the aedeagus was illustrated in the original description together with fragments of terminal abdominal segments which on the Fig. 207 in Franz (1980) are shown as if they were integral parts of the median lobe. After re-mounting and removing the remnants of abdomen, it turned out that the aedeagus ( Figs. 28–29) has slender parameres and the basal orifice is located at base of the dorsal wall. Except for two apical setae on each paramere, the aedeagus resembles that of Microscydmus (which has a single apical seta on each paramere). The characters mentioned by Franz as different in Mimoscydmus and Microscydmus are then only the lateral pronotal edges (present in Mimoscydmus and absent in Microscydmus ) and the ante-basal transverse groove on the pronotum (present in Mimoscydmus , absent in Microscydmus ). During the present study further differences between Mimoscydmus and Microscydmus were found: the hypostomal ridges long, recurved and extending nearly to the posterior tentorial pits (short and with posterior ends distant from pits in Microscydmus ); the internal parts of prothoracic hypomera extremely narrow and demarcated from prosternum only behind procoxal sockets (in Microscydmus internal parts of hypomera very broad and demarcated from prosternum also in front of procoxal sockets); the prosternal intercoxal process carinate and distant from the carina separating procoxal cavities from the basisternal part of sternum (prosternal process in Microscydmus developed as a subtriangular protuberance connected to the anterior carina of procoxal cavities); mesoventrite with ventro-lateral foveae (absent in Microscydmus ); setose impressions of mesoventrite absent (present and connected in middle in Microscydmus ); mesoventral intercoxal process anteriorly connected with the anterior ridge of mesoventrite (separated from anterior ridge in Microscydmus ); the stalk of the metafurca elongate (about as long as broad in Microscydmus ); and each elytron with single rudiment of asetose basal fovea (one large and setose basal fovea in Microscydmus ). Major differences between Microscydmus and all genera treated in the present paper are compiled in Table 1.

The other species originally included in Mimoscydmus , M. baruerii , is here removed from this genus and placed in Amimoscydmus gen. nov.

Mimoscydmus brasiliensis Franz ( Figs. 3, 13–16, 28–29, 33, 37)

Mimoscydmus brasiliensis Franz, 1980: 220 , Fig. 207.

Material studied. Holotype: ♂: three labels ( Fig. 33): "Umg. Manaus / Amazonasgebiet / Brasil, lg. L. Beck" with " 11 " on the reverse side [white, printed; reverse handwritten], " Mimoscydmus / brasiliensis / m. / det. H. Franz" [white, handwritten and printed], " Typus " [red, handwritten] (NHMW).

Diagnosis. This is the only known species of the re-defined Mimoscydmus and can be identified on the basis of the generic characters and the aedeagus.

Redescription. Body of male ( Fig. 3) moderately convex, elongate and slender, with moderately long appendages, BL 0.65 mm; glossy, body light brown with indistinctly darkened head and yellowish-brown appendages, vestiture yellowish.

Head ( Figs. 3, 13– 14) approximately hexagonal, broadest at eyes, HL 0.13 mm, HW 0.15 mm; tempora much shorter than eyes, strongly convergent caudad; vertex and frons confluent, moderately convex and together about as long as broad; supraantennal tubercles indistinct. Punctures on head dorsum fine and sparse, inconspicuous; setae very short, sparse and recumbent. Antennae slender, with moderately distinctly demarcated club composed of antennomeres IX–XI and antennomere VIII distinctly smaller than VII, AnL 0.28 mm; antennomeres I–II elongate; III–VI and VIII each slightly transverse; VII and IX–X strongly transverse; XI only slightly longer than broad, with subconical, blunt apex.

Pronotum ( Fig. 3) in dorsal view oval, broadest between middle and anterior third, PL 0.18 mm, PW 0.18 mm; anterior margin weakly rounded; lateral margins strongly rounded in anterior half and slightly S-shaped in posterior half, strongly convergent toward obtuse but distinctly marked hind pronotal angles; posterior margin weakly arcuate; base of pronotum with long, deep and straight transverse ante-basal groove. Punctures on pronotal disc fine and inconspicuous; setae on dorsal surface sparse, thin, very short and recumbent, those on sides of pronotum ( Fig. 15) dense, thick and long.

Elytra ( Fig. 3) oval, about as convex as pronotum, broadest slightly behind middle, EL 0.35 mm, EW 0.25 mm, EI 1.40; humeral calli distinct; basal impressions shallow and short, basal fovea indiscernible in dry-mounted specimen; elytral apices separately rounded. Punctures on elytral disc as fine as those on pronotum; setae very short, sparse and recumbent. Hind wings well-developed, about twice as long as elytra.

Legs ( Fig. 3) moderately long and slender, without modifications.

Aedeagus ( Figs. 28–29) elongate, AeL 0.08 mm, median lobe broadest near base and narrowing distally; internal armature symmetrical and lightly sclerotized; parameres slender, each with one apical and one subapical seta.

Female. Unknown.

Distribution ( Fig. 37). Northern Brazil, state Amazonas.

Remarks. In the original description Franz (1980) gives further collecting data for the holotype: a palm forest near Manaus.