Amimoscydmus, Jałoszyński, Paweł, 2013

Jałoszyński, Paweł, 2013, Revision of Neotropical genera Microraphes Franz, Heteroscydmus Franz and Mimoscydmus Franz (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 3722 (2), pp. 245-266 : 259-264

Amimoscydmus gen. nov.

Type species: Amimoscydmus baruerii (Franz, 1980) ; here designated.

Diagnosis. Male and female: head short, with vertex not expanded dorso-caudad; occipital constriction only slightly narrower than vertex; thick and long bristles on head and prothorax absent; 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 without lateral edges; base of pronotum with long transverse groove, without pits but with short and distinct sub-lateral carinae near each posterior corner; basisternal part of prosternum several times shorter than procoxal cavities; prosternum with fine and barely expanding ventrally prosternal intercoxal carina not connected to anterior carina of procoxal cavities; prothoracic hypomeral ridges complete; pronotosternal sutures visible only along sides of basisternal part of prosternum; internal parts of hypomera fused with prosternum both behind and in front of procoxal sockets; 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 without lateral foveae; mesocoxal projection with barely discernible posterior lobe; metacoxae narrowly separated by metaventral intercoxal process composed of a pair of long spines; each elytron with two rudimentary and asetose basal foveae. Male: aedeagus symmetrical, with free parameres.

Description. Body of male ( Fig. 4 ) moderately convex, elongate and slender, with moderately long appendages, BL 0.58–0.63 mm; cuticle glossy, light brown, finely setose.

Head ( Figs. 4 , 17–19 ) with anterior part (in front of occipital constriction) transverse, with moderately large eyes; occipital constriction ( Figs. 17–19 ; occ) only slightly narrower than vertex; tempora ( Fig. 17–18 ; tm) long and weakly convergent caudad, without bristles; vertex ( Fig. 17 ; vt) broader than long, convex, not projecting dorso-caudad; frons ( Fig. 17 ; fr) transverse and subtrapezoidal with anterior margin strongly expanding anterad and forming small median denticle, posteriorly confluent with vertex; frontoclypeal groove absent; antennal insertions broadly separated.

Labrum transverse with rounded anterior margin. Mandibles ( Figs. 17, 19 ; md) subtriangular, with broad base and slender apical part, without sub-apical tooth, prostheca not visible. Each maxilla ( Fig. 19 ) with subtriangular basistipes ( Fig. 19 ; bst), elongate galea ( Fig. 19 ; gal) and lacinia ( Fig. 19 ; lac) and moderately long maxillary palp ( Fig. 19 ; mxp) composed of only slightly elongate palpomere I, strongly elongate, pedunculate palpomere II, broad and stout palpomere III broadest in distal third, and small, strongly elongate, subconical and pointed palpomere IV with distinctly delimited and long apical part.

Labium ( Fig. 19 ) with transverse submentum ( Fig. 19 ; smn) not demarcated posteriorly and fused laterally with postcardinal parts of hypostomae, subtrapezoidal mentum ( Fig. 19 ; mn); and short prementum bearing narrowly separated at bases small 3-segmented labial palps ( Fig. 19 ; lp). Hypostomal ridges ( Fig. 19 ; hr) short, visible only just behind cardines.

Gular plate ( Fig. 19 ; gp) large and distinctly narrowing anterad; gular sutures ( Fig. 19 ; gs) superficial; posterior tentorial pits ( Fig. 19 ; ptp) small but distinct, located anterior to transverse arcuate impression delimiting ventrally 'neck region' from anterior part of head.

Antennae ( Figs. 4 , 19 ) with distinctly delimited club composed of antennomeres IX–XI.

Pronotum ( Fig. 4 ) 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 absent; sub-lateral carinae present, short but distinct and located on dorsal surface near each hind pronotal corner; base of pronotum with distinct and long transverse groove, without pits; sides of pronotum with thin setae ( Fig. 20 ).

Prosternum ( Fig. 20 ) with very short basisternal part ( Fig. 20 ; bst) indistinctly demarcated from procoxal cavities ( Fig. 20 ; pcc) by straight carina; median part of sternum with prosternal intercoxal process developed as fine carina weakly expanded ventrally and not connected to anterior carina of procoxal cavities; procoxal sockets ( Fig. 20 ; pcs) closed by broad postero-lateral lobes of sternum; hypomera ( Fig. 20 ; hy) elongate, divided into broad lateral parts and moderately broad internal (adcoxal) parts, adcoxal parts of hypomera fused with prosternum both posterior and anterior to procoxal sockets; pronotosternal sutures ( Fig. 20 ; nss) visible only along sides of basisternal parts of prosternum; hypomeral ridges ( Fig. 20 ; hyr) complete, anteriorly connected to pronotosternal sutures.

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

Mesoventrite ( Fig. 21 ) with narrow anterior ridge ( Fig. 20 ; ar); mesoventral intercoxal process ( Fig. 20 ; msvp) narrow and moderately expanded ventrally, anteriorly connected with anterior ridge, posterior part of mesoventral intercoxal process with short posterior arms ( Fig. 21 ; pa); asetose lateral impressions ( Fig. 21 ; ai) present, posteriorly demarcated not by carina but by a row of setiferous punctures; mesanepisternum with short prepectus ( Fig. 21 ; pre) and posterior part largely hidden in ventral view; mesepimeron not visible in ventral view; sides of mesothorax without foveae; mesocoxal projections ( Fig. 21 ; mcp) with mesocoxal sockets ( Fig. 21 ; mscs) located on their meso-ventral surface and with small, barely discernible and setose posterior lobes ( Fig. 21 ; pl).

Metaventrite ( Fig. 21 ; vIII) longer than broad, anteriorly fused with mesoventrite, posteriorly shallowly bisinuate and with narrow median metaventral intercoxal process ( Fig. 21 ; mtvp) composed of a pair of long spines. Metanepisterna and metepimera narrow.

Metafurca ( Fig. 21 ) with short and broad stalk and divergent lateral furcal arms ( Fig. 21 ; mtfa).

Elytra ( Fig. 4 ) oval, each with two rudiments of asetose basal foveae 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. 4 , 21 ) 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 ( Fig. 21 ) unmodified, suture between VII and VIII barely marked.

Aedeagus ( Figs. 22–23 ) symmetrical, AeL 0.13 mm, lightly sclerotized and thin-walled, with symmetrical internal armature composed of elongate sclerites; parameres free, slender.

Spermatheca ( Fig. 21 ; spt) globular, darkly sclerotized, located near base of abdomen.

Distribution and composition. Amimoscydmus is represented by a single species known from the southeastern part of Brazil ( Fig. 38 ).

Etymology. Amimoscydmus is a combination of the genus name Mimoscydmus with a prefix -a, to underline its separate position from the highly similar Mimoscydmus . Gender masculine.

Remarks. The general appearance of Amimoscydmus is highly similar to that of Mimoscydmus and Microscydmus and fine details must be examined to correctly identify these genera, either by SEM or in transparent mounts. Several important characters differentiate Amimoscydmus from Mimoscydmus : the hypostomal ridges short, visible only just behind cardines (long and extending nearly to posterior tentorial pits in Mimoscydmus ); broad internal (adcoxal) parts of prothoracic hypomera fused with the prosternum not only in front of but also behind procoxal sockets (extremely narrow and fused with prosternum only in front of procoxal sockets in Mimoscydmus ); pronotum without lateral carinae but with fine and short sub-lateral carinae on its dorsal surface (pronotum with fine lateral edges and without sub-lateral carinae in Mimoscydmus ); bristles on sides of pronotum absent (present in Mimoscydmus ); the mesoventrite without lateral foveae (with deep ventro-lateral foveae in Mimoscydmus ); and a pair of rudimentary basal elytral foveae (single fovea in Mimoscydmus ). Amimoscydmus is highly similar to Microscydmus , from which it can be easily distinguished on the basis of the pronotal groove (a pair of pits in Microscydmus ); rudimentary and asetose basal elytral foveae (one large and setose fovea in Microscydmus ); the internal (adcoxal) parts of prothoracic hypomera fused with prosternum anterior and posterior to procoxal sockets (in Microscydmus hypomera behind procoxal sockets demarcated from prosternum); and the mesoventral intercoxal process connected anteriorly with the anterior ridge of mesoventrite (distant from anterior ridge in Microscydmus ). Major differences between Microscydmus and all genera treated in the present paper are compiled in Table 1.

Amimoscydmus baruerii (Franz) , comb. nov. ( Figs. 4 , 17–21 , 30 , 34 , 38 )

Mimoscydmus baruerii Franz, 1980: 220 , Fig. 208.

Material studied. Paratypes: 2 ♀♀: each with two labels ( Fig. 34 ): "Barueri, Sao Paulo / Brasil, lg. K. Lenko", on the reverse side with "No. 27" [white, printed; reverse handwritten], " Mimoscydmus / baruerii / m. / det. H. Franz ' PARATYPUS " [yellow, printed and handwritten] (NHMW). Additional material: 3 ♂♂, 4 ♀♀, same locality labels but with " Microscydmus [sic!] baruerii " identification label and only six annotated as paratypes (NHMW) (see Remarks).

Diagnosis. This is the only known species of Amimoscydmus and can be identified on the basis of the generic characters and the aedeagus.

Redescription. Body of male ( Fig. 4 ) moderately convex, elongate and slender, with moderately long appendages, BL 0.59–0.63 mm (mean 0.61 mm); glossy, body uniformly light brown, in some specimens head slightly darker, appendages yellowish-brown, vestiture yellowish.

Head ( Fig. 4 ) approximately subquadrate, broadest at eyes, HL 0.10 mm, HW 0.13–0.14 mm (mean 0.13 mm); tempora slightly shorter than eyes, bent at nearly right angle and rounded; vertex and frons confluent, moderately convex and together broader than long; supraantennal tubercles barely discernible. Punctures on head dorsum fine and sparse, inconspicuous; setae short, sparse and suberect. Antennae moderately slender, with distinctly demarcated club composed of antennomeres IX–XI, AnL 0.25 mm; antennomeres I–II elongate; III–IX distinctly transverse; XI about as long as broad, with subconical, blunt apex.

Pronotum ( Fig. 4 ) in dorsal view oval, broadest slightly anterior to middle, PL 0.16–0.18 mm (mean 0.17 mm), PW 0.16–0.18 mm (mean 0.17 mm); anterior margin weakly arcuate; lateral margins strongly rounded on entire length, strongly convergent toward obtuse but sharply marked hind pronotal angles; posterior margin weakly arcuate; base of pronotum with long, deep and straight transverse ante-basal groove and distinct but short sublateral longitudinal carinae. Punctures on pronotal disc fine and inconspicuous; setae on dorsal surface sparse, thin, short and suberect.

Elytra ( Fig. 4 ) oval, about as convex as pronotum, broadest slightly behind middle, EL 0.33–0.35 mm (mean 0.34 mm), EW 0.25–0.26 mm (mean 0.26 mm), EI 1.30–1.33; humeral calli distinct; basal impressions shallow and short, basal foveae indiscernible in dry-mounted specimens; elytral apices separately rounded. Punctures on elytral disc as fine as those on pronotum; setae short, sparse and nearly recumbent. Hind wings well-developed, about twice as long as elytra.

Legs ( Fig. 4 ) moderately long and slender, without modifications.

Aedeagus ( Fig. 30 ) elongate, AeL 0.13 mm, median lobe oval with subtriangular apical part; internal armature composed of sub-basally located pair of elongate and curved sclerites and elongate sub-apical lateral structures; parameres slender, each with single apical seta.

Female ( Figs. 19–21 ). Similar to male but differing in distinctly smaller eyes, and in consequence tempora longer than eyes and head broadest at or slightly behind eyes ( Fig. 17 ). BL 0.58–0.60 mm (mean 0.59 mm); HL 0.10 mm, HW 0.11–0.13 mm (mean 0.12 mm), AnL 0.23 mm; PL 0.15–0.18 mm (mean 0.16 mm), PW 0.15–0.16 mm (mean 0.16 mm); EL 0.33 mm, EW 0.23–0.24 mm (mean 0.23 mm), EI 1.37–1.44.

Distribution ( Fig. 38 ). South-eastern Brazil, state São Paulo.

Remarks. The holotype of this species is preserved at the Instituto Biologico São Paulo, Brazil, and my efforts to borrow this specimen have failed. In the original description (Franz 1980) only the holotype and two paratypes are mentioned. However, nine specimens are preserved at the NHMW. Two of them are labeled " Mimoscydmus baruerii " and seven as " Microscydmus baruerii ", and eight of them are labeled as paratypes, while apparently all come from the same series collected by Lenko. Franz never described a Microscydmus baruerii , and all the specimens studied during the present study seem to be conspecific. It is not possible to clarify whether Franz studied all of them before describing Mimoscydmus baruerii and only erroneously gave the information on 2 paratypes in his paper, or the remaining specimens (those labeled as Microscydmus ) come from a later time, and were erroneously labeled as paratypes.

In the original description Franz (1980) gives further collecting data for the holotype and two paratypes: Barueri near São Paulo, in a nest of Camponotus rufipes , 22.10.1967 and 0 7.01.1968, leg. C. Lenko.

Figures

FIGURES 1 – 4. Dorsal habitus of male holotype (1 – 3) and male paratype (4). Microraphes pygmaeus Franz (1); Heteroscydmus yapacariensis Franz (2); Mimoscydmus brasiliensis Franz (3); Amimoscydmus baruerii (Franz) (4).

FIGURES 17 – 21. Morphology of Amimoscydmus baruerii (Franz), paratype female. Head in dorsal (17), lateral (18) and ventral (19) views; prothorax in ventral view (20); pterothorax and abdomen in ventral view (21). Abbreviations: ai, asetose impression; ar, anterior ridge; bst, basisternal part of prosternum; cd, cardo; cl, clypeus; fr, frons; gal, galea; gen, gena; gp, gular plate; gs, gular suture; fo, foramen occipitale; hr, hypostomal ridge; hy, hypomeron; hyr, hypomeral ridge; lac, lacinia; lp, labial palp; mcp, mesocoxal projection; md, mandible; mn, mentum; mscc, mesocoxal cavity; mscs, mesocoxal socket; msff, mesofurcal fovea; msvp, mesoventral intercoxal process; mtfa, metafurcal arm; mtfs, metafurcal stalk; mtvp, metaventral intercoxal process; mxp, maxillary palp; nr, neck region; nss, pronotosternal suture; occ, occipital constriction; pa, posterior arm of mesoventral intercoxal process; pcc, procoxal cavity; pcs, procoxal socket; pf, profurca; pff, profurcal fovea; ppf, palpifer; pre, prepectus; pstp, prosternal intercoxal process; ptp, posterior tentorial pit; smn, submentum; spt, spermatheca; tm, temple; vIII, metaventrite; vt, vertex.

FIGURES 22 – 30. Aedeagi in ventral (22, 24, 27, 28, 30), dorsal (25) and lateral (23, 26, 29) views. Microraphes pygmaeus Franz, holotype (22); Heteroscydmus yapacariensis Franz, holotype (24 – 26) and paratype (27); Mimoscydmus brasiliensis Franz, holotype (28 – 29); Amimoscydmus baruerii (Franz), holotype (30).

FIGURES 35 – 38. Distribution of revised taxa. Microraphes pygmaeus Franz (35); Heteroscydmus yapacariensis Franz (36); Mimoscydmus brasiliensis Franz (37); Amimoscydmus baruerii (Franz) (38).

FIGURES 31 – 34. Original set of labels of holotypes (31 – 33) and paratype (34). Microraphes pygmaeus Franz (31); Heteroscydmus yapacariensis Franz (32); Mimoscydmus brasiliensis Franz (33); Amimoscydmus baruerii (Franz) (34).