Leascydmus , Jałoszyński, Paweł, 2014

Jałoszyński, Paweł, 2014, ' The curse of Horaeomorphus ': taxonomy of misplaced Australian Cyrtoscydmini (Coleoptera: Staphylinidae: Scydmaeninae), Zootaxa 3828 (1), pp. 1-76: 18-21

publication ID

http://dx.doi.org/10.11646/zootaxa.3828.1.1

publication LSID

lsid:zoobank.org:pub:B2FEAE60-7E51-45FA-A38F-930A084A5AAA

persistent identifier

http://treatment.plazi.org/id/03F68791-FFC6-181D-8FFE-3BC002C9FDC8

treatment provided by

Plazi

scientific name

Leascydmus
status

gen. n.

Leascydmus  gen. n.

Type species: Scydmaenus simplicicornis Lea, 1910: 185  (here designated).

Diagnosis. Body ( Figs. 46–48View FIGURES 46 – 48) elongate and strongly convex; head ( Fig. 37View FIGURES 37 – 41) short and convex; vertex ( Fig. 37View FIGURES 37 – 41; vt) not projecting dorsocaudad, its posterior margin convex or nearly straight; supraantennal tubercles barely marked and not accompanied posteriorly by pits; frontoclypeal suture or groove absent; eyes located in middle of head; tempora ( Fig. 37View FIGURES 37 – 41; tm) long and strongly curved toward occipital constriction; tempora, genae and postgenae without bristles; 'neck region' distinctly demarcated from anterior part of head capsule by constriction and much narrower than vertex; hypostomal ridges ( Fig. 38View FIGURES 37 – 41; hr) rudimentary, indistinctly marked only just behind cardines; posterior tentorial pits ( Fig. 38View FIGURES 37 – 41; ptp) elongate and located distinctly in front of transverse groove demarcating 'neck' ventrally; submentum ( Fig. 38View FIGURES 37 – 41; smn) without lateral sutures; each mandible with apical tooth sharply demarcated from basal part and densely setose prostheca ( Fig. 40View FIGURES 37 – 41; pst), subapical teeth absent; maxillary palpomeres III and IV ( Fig. 41View FIGURES 37 – 41; mxp 3–4) slender, strongly elongate; pronotum ( Figs. 42View FIGURES 42 – 45, 46, 48View FIGURES 46 – 48) without antebasal pits or grooves, only with barely noticeable, shallow and diffused transverse impression; prosternum laterally demarcated from hypomera by pronotosternal sutures ( Fig. 43View FIGURES 42 – 45; nss), without intercoxal process or carina; procoxal sockets ( Fig. 43View FIGURES 42 – 45; pcs) narrowly open; prothoracic hypomera ( Fig. 43View FIGURES 42 – 45; hy) with large internal (adcoxal) parts demarcated from sides of pronotum by incomplete hypomeral ridges ( Fig. 43View FIGURES 42 – 45; hyr) developed only anteriorly; sides of prothorax ( Fig. 43View FIGURES 42 – 45) with short and dense thick bristles located only in anteroventral portion and not visible or barely visible in dorsal view; mesoventrite with short anterior ridge ( Fig. 45View FIGURES 42 – 45; ar) without posterior median projection; mesoventral process ( Fig. 45View FIGURES 42 – 45; msvp) narrow and weakly expanding ventrally but distinct and clearly separating mesocoxae, interrupted near anterior margins of mesocoxal cavities; ventro- and dorsolateral foveae ( Fig. 45View FIGURES 42 – 45; vlf, dlf) present; anterior metaventral process ( Fig. 45View FIGURES 42 – 45; amvp) present; metaventral intercoxal process ( Fig. 45View FIGURES 42 – 45; mtvp) broadly separating metacoxae, without spines, with shallowly concave posterior margin; each elytron with two asetose rudiments of basal foveae ( Fig. 44View FIGURES 42 – 45; bef) not connected by groove and barely discernible in dry-mounted specimens; aedeagus ( Figs. 49–56View FIGURES 49 – 52View FIGURES 53 – 56) with free and slender parameres.

Description. Body ( Figs. 46, 48View FIGURES 46 – 48) 2.20–2.58 in length, strongly convex, elongate but moderately slender, with long appendages, pigmentation from reddish-brown to nearly black, cuticle setose.

Head ( Figs. 37 –38View FIGURES 37 – 41, 46, 48View FIGURES 46 – 48) with occipital constriction ( Fig. 37View FIGURES 37 – 41; occ) much narrower than vertex and dividing the head capsule into exposed anterior part and narrow posterior 'neck region' retracted into prothorax; eyes small and slightly oval, located in median part of head; tempora ( Fig. 37View FIGURES 37 – 41; tm) long and strongly curved posteromesally, without bristles; vertex ( Fig. 37View FIGURES 37 – 41; vt) transverse, uniformly convex, not projecting dorso-caudad, with evenly rounded and convex posterior margin sharply demarcated from occiput; frons ( Fig. 37View FIGURES 37 – 41; fr) confluent with vertex, transverse and subtrapezoidal, evenly convex, anteriorly steeply but not abruptly lowering toward labrum; frontoclypeal groove absent; antennal insertions broadly separated, located beneath feebly developed supraantennal tubercles.

Labrum ( Fig. 39View FIGURES 37 – 41) transverse with rounded anterior margin and narrow translucent marginal velum, with six thick anteroventral (anterior epipharyngeal) bristle-like sensilla projecting from under anterior margin, and with large number of moderately long dorsal setae. Mandibles ( Fig. 40View FIGURES 37 – 41) symmetrical, subtriangular, each with broad base and curved, rapidly narrowing and pointed apical part; prostheca ( Fig. 40View FIGURES 37 – 41; pst) present, with dense thin setae along mesal mandibular margin, slightly expanding onto dorsal surface of mandible and reaching mandibular base. Maxilla ( Fig. 41View FIGURES 37 – 41) composed of small cardo ( Fig. 41View FIGURES 37 – 41; cd) bearing several setae; subtriangular basistipes ( Fig. 41View FIGURES 37 – 41; bst); elongate mediostipes ( Fig. 41View FIGURES 37 – 41; mst); elongate galea ( Fig. 41View FIGURES 37 – 41; gal) and lacinia ( Fig. 41View FIGURES 37 – 41; lac); large, elongate palpifer ( Fig. 41View FIGURES 37 – 41; pfp); and strongly elongate and moderately large maxillary palp ( Fig. 38View FIGURES 37 – 41; mxp) composed of elongate palpomere I ( Fig. 41View FIGURES 37 – 41; mxp 1), strongly elongate, clavate and slender palpomere II ( Fig. 41View FIGURES 37 – 41; mxp 2), large and strongly elongate palpomere III ( Fig. 41View FIGURES 37 – 41; mxp 3) broadest near distal third, and small, slender, subconical and pointed palpomere IV ( Fig. 41View FIGURES 37 – 41; mxp 4). Labium ( Fig. 38View FIGURES 37 – 41) with large submentum ( Fig. 38View FIGURES 37 – 41; smn) not demarcated posteriorly from gular plate and not demarcated laterally from postcardinal parts of hypostomae; subrectangular and transverse mentum ( Fig. 38View FIGURES 37 – 41; mn); and relatively long prementum ( Fig. 38View FIGURES 37 – 41; pmn) bearing narrowly separated at bases long 3 -segmented labial palps and ligula with single median bristle. Hypostomal ridges ( Fig. 38View FIGURES 37 – 41; hr) superficial and visible only just behind cardines.

Gular plate ( Fig. 38View FIGURES 37 – 41; gp) large and subtrapezoidal, with rapidly narrowed anterior portion; gular sutures ( Fig. 38View FIGURES 37 – 41; gs) superficial; posterior tentorial pits ( Fig. 38View FIGURES 37 – 41; ptp) narrow and arcuate, located clearly in front of transverse groove ventrally demarcating 'neck region'.

Antennae ( Figs. 46, 48View FIGURES 46 – 48) long and slender, gradually but only slightly thickening distally; antennomere XI conspicuously long.

Prothorax ( Figs. 42 –43View FIGURES 42 – 45, 46, 48View FIGURES 46 – 48) in dorsal view subtrapezoidal, broadest anterior to middle, with rounded anterior margin and anterior parts of lateral margins, with weakly marked, blunt and obtuse anterior corners; posterior corners blunt and obtuse; posterior margin weakly arcuate. Pronotum without antebasal pits and grooves, and without sublateral carinae or lateral edges, with indistinct, shallow and diffused antebasal transverse impression ( Fig. 42View FIGURES 42 – 45). Sides of pronotum mostly with thin setae, only anteroventral parts of hypomera with thick bristles ( Fig. 43View FIGURES 42 – 45).

Prosternum ( Fig. 43View FIGURES 42 – 45) with moderately short basisternal part ( Fig. 43View FIGURES 42 – 45; bst) indistinctly demarcated from procoxal cavities ( Fig. 43View FIGURES 42 – 45; pcc); median part of sternum slightly raised but not carinate; procoxal sockets ( Fig. 43View FIGURES 42 – 45; pcs) open; hypomera ( Fig. 43View FIGURES 42 – 45; hy) elongate, each divided into broad lateral part confluent with pronotum and narrower but still broad internal (adcoxal) part; hypomeral ridges ( Fig. 43View FIGURES 42 – 45; hyr) incomplete, visible only along anterior margins of adcoxal parts of hypomera; pronotosternal sutures ( Fig. 43View FIGURES 42 – 45; nss) entire.

Mesocutellum ( Fig. 44View FIGURES 42 – 45; scl 2) subtriangular, in intact specimens hidden by posterior margin of pronotum overlapping with elytral base; mesoscutoscutellar suture present.

Mesoventrite ( Fig. 45View FIGURES 42 – 45) with narrow and indistinctly demarcated anterior ridge ( Fig. 45View FIGURES 42 – 45; ar); mesoventral intercoxal process ( Fig. 45View FIGURES 42 – 45; msvp) carinate and moderately expanding ventrally, anteriorly separated from anterior ridge and interrupted near anterior margins of mesocoxal cavities; sides of mesoventrite with shallow concave procoxal rests ( Fig. 45View FIGURES 42 – 45; pcr) filled with short setae (= setose impressions) but without asetose impressions; mesanepisternum with moderately long prepectus ( Fig. 45View FIGURES 42 – 45; pre), sides of mesoventrite with two pairs of narrow, deep and setose ventrolateral and dorsolateral foveae ( Fig. 45View FIGURES 42 – 45; vlf, dlf); mesocoxal projections ( Fig. 45View FIGURES 42 – 45; mcp) prominent, with mesocoxal sockets located on their mesal surface and not visible in ventral view.

Metaventrite ( Fig. 45View FIGURES 42 – 45; v 3) subrectangular, anteriorly fused with mesoventrite, posteriorly moderately deeply bisinuate and with broad, shallowly emarginate metaventral intercoxal process ( Fig. 45View FIGURES 42 – 45; mtvp); anteriorly with short and narrow anterior metaventral process ( Fig. 45View FIGURES 42 – 45; amvp). Metanepisterna and metepimera narrow.

Metafurca ( Fig. 45View FIGURES 42 – 45) with short stalk and divergent lateral furcal arms ( Fig. 45View FIGURES 42 – 45; lmfa).

Elytra ( Figs. 44View FIGURES 42 – 45, 46, 48View FIGURES 46 – 48) oval, each with two asetose rudiments of basal foveae ( Fig. 44View FIGURES 42 – 45; bef) barely discernible in dry-mounted specimens; each humerus with small and blunt but distinct humeral denticle ( Fig. 42View FIGURES 42 – 45; hd); subhumeral lines absent.

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

Legs ( Figs. 46, 48View FIGURES 46 – 48) long and slender; procoxae subglobose, mesocoxae oval, metacoxae strongly transverse; metatrochanters relatively long; all femora strongly clavate; tibiae and tarsi long and slender.

Aedeagus ( Figs. 49–56View FIGURES 49 – 52View FIGURES 53 – 56) elongate and darkly sclerotized, relatively thick-walled, with symmetrical median lobe but strongly asymmetrical and complicated subapical assemblage of internal sclerites; parameres free and slender, with apical setae.

Etymology. Leascydmus  is a name dedicated to Arthur Mills Lea, an Australian entomologist who described many Scydmaeninae  and in the description of Scydmaenus simplicicornis  wrote: "the species may eventually be regarded as belonging to a new genus", which proved correct. Gender masculine.

Composition and distribution. Two species of Leascydmus  are known from south-eastern Australia (Victoria and New South Wales; Fig. 194View FIGURES 193 – 198).

Remarks. Leascydmus  is a remarkable genus because of its superficial similarity to Scydmaenus Latreille, 1802  . The general shape of the pronotum and elytra, the broad metaventral intercoxal process and relatively long metatrochanters resemble some subgenera of Scydmaenus  , from which Leascydmus  differs in the diagnostic characters of Cyrtoscydmini  (e.g., the subconical maxillary palpomere IV; discussed in Jałoszyński 2012 c). Among Australian Cyrtoscydmini  open procoxal sockets can be found only in Palaeoscydmaenus Franz  , but this genus has a clearly different habitus, with subtriangular head, the 'neck region' nearly as broad as vertex and much less distinctly demarcated from the anterior part of the head capsule, and the pronotum elongate and broadest in the anterior part. Besides, Palaeoscydmaenus  belongs to a group of genera characterized by the submentum demarcated laterally by complete lateral sutures, which are absent in Leascydmus  . Leascydmus  differs from all Australian genera without lateral sutures of submentum in rudimentary hypostomal ridges (shared only by Microscydmus  and Penicillidmus, but these genera include beetles not reaching 1 mm in length, with 3 -segmented antennal club, and antebasal pits on pronotum), tempora, genae and postgenae covered only with setae, without bristles, open procoxal sockets and broadly separated metacoxae (character shared with at least some subgenera of Euconnus  , including Euconnus  s. str., but the latter genus has pits and sometimes transverse grooves on the base of pronotum and long, continuous and strongly expanding ventrally, keel-shaped mesoventral intercoxal process). The short head with arcuate posterior margin of convex vertex, short pronotum without pits or grooves, humeral denticles and strongly elongate antennae with the antennomere XI as long as IX–X together are sufficient to identify Leascydmus  .