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	https://doi.org/ 10.11646/zootaxa.3828.1.1
publication LSID	lsid:zoobank.org:pub:B2FEAE60-7E51-45FA-A38F-930A084A5AAA
DOI	https://doi.org/10.5281/zenodo.6141056
persistent identifier	https://treatment.plazi.org/id/03F68791-FFC6-181D-8FFE-3BC002C9FDC8
treatment provided by	Plazi
scientific name	Leascydmus
status	gen. nov.

Treatment

Leascydmus View in CoL gen. n.

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

Diagnosis. Body ( Figs. 46–48 View FIGURES 46 – 48 ) elongate and strongly convex; head ( Fig. 37 View FIGURES 37 – 41 ) short and convex; vertex ( Fig. 37 View 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. 37 View 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. 38 View FIGURES 37 – 41 ; hr) rudimentary, indistinctly marked only just behind cardines; posterior tentorial pits ( Fig. 38 View FIGURES 37 – 41 ; ptp) elongate and located distinctly in front of transverse groove demarcating 'neck' ventrally; submentum ( Fig. 38 View FIGURES 37 – 41 ; smn) without lateral sutures; each mandible with apical tooth sharply demarcated from basal part and densely setose prostheca ( Fig. 40 View FIGURES 37 – 41 ; pst), subapical teeth absent; maxillary palpomeres III and IV ( Fig. 41 View FIGURES 37 – 41 ; mxp3–4) slender, strongly elongate; pronotum ( Figs. 42 View FIGURES 42 – 45 , 46, 48 View 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. 43 View FIGURES 42 – 45 ; nss), without intercoxal process or carina; procoxal sockets ( Fig. 43 View FIGURES 42 – 45 ; pcs) narrowly open; prothoracic hypomera ( Fig. 43 View FIGURES 42 – 45 ; hy) with large internal (adcoxal) parts demarcated from sides of pronotum by incomplete hypomeral ridges ( Fig. 43 View FIGURES 42 – 45 ; hyr) developed only anteriorly; sides of prothorax ( Fig. 43 View 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. 45 View FIGURES 42 – 45 ; ar) without posterior median projection; mesoventral process ( Fig. 45 View 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. 45 View FIGURES 42 – 45 ; vlf, dlf) present; anterior metaventral process ( Fig. 45 View FIGURES 42 – 45 ; amvp) present; metaventral intercoxal process ( Fig. 45 View FIGURES 42 – 45 ; mtvp) broadly separating metacoxae, without spines, with shallowly concave posterior margin; each elytron with two asetose rudiments of basal foveae ( Fig. 44 View FIGURES 42 – 45 ; bef) not connected by groove and barely discernible in dry-mounted specimens; aedeagus ( Figs. 49–56 View FIGURES 49 – 52 View FIGURES 53 – 56 ) with free and slender parameres.

Description. Body ( Figs. 46, 48 View 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. 37–38 View FIGURES 37 – 41 , 46, 48 View FIGURES 46 – 48 ) with occipital constriction ( Fig. 37 View 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. 37 View FIGURES 37 – 41 ; tm) long and strongly curved posteromesally, without bristles; vertex ( Fig. 37 View FIGURES 37 – 41 ; vt) transverse, uniformly convex, not projecting dorso-caudad, with evenly rounded and convex posterior margin sharply demarcated from occiput; frons ( Fig. 37 View 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. 39 View 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. 40 View FIGURES 37 – 41 ) symmetrical, subtriangular, each with broad base and curved, rapidly narrowing and pointed apical part; prostheca ( Fig. 40 View 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. 41 View FIGURES 37 – 41 ) composed of small cardo ( Fig. 41 View FIGURES 37 – 41 ; cd) bearing several setae; subtriangular basistipes ( Fig. 41 View FIGURES 37 – 41 ; bst); elongate mediostipes ( Fig. 41 View FIGURES 37 – 41 ; mst); elongate galea ( Fig. 41 View FIGURES 37 – 41 ; gal) and lacinia ( Fig. 41 View FIGURES 37 – 41 ; lac); large, elongate palpifer ( Fig. 41 View FIGURES 37 – 41 ; pfp); and strongly elongate and moderately large maxillary palp ( Fig. 38 View FIGURES 37 – 41 ; mxp) composed of elongate palpomere I ( Fig. 41 View FIGURES 37 – 41 ; mxp1), strongly elongate, clavate and slender palpomere II ( Fig. 41 View FIGURES 37 – 41 ; mxp2), large and strongly elongate palpomere III ( Fig. 41 View FIGURES 37 – 41 ; mxp3) broadest near distal third, and small, slender, subconical and pointed palpomere IV ( Fig. 41 View FIGURES 37 – 41 ; mxp4). Labium ( Fig. 38 View FIGURES 37 – 41 ) with large submentum ( Fig. 38 View FIGURES 37 – 41 ; smn) not demarcated posteriorly from gular plate and not demarcated laterally from postcardinal parts of hypostomae; subrectangular and transverse mentum ( Fig. 38 View FIGURES 37 – 41 ; mn); and relatively long prementum ( Fig. 38 View FIGURES 37 – 41 ; pmn) bearing narrowly separated at bases long 3-segmented labial palps and ligula with single median bristle. Hypostomal ridges ( Fig. 38 View FIGURES 37 – 41 ; hr) superficial and visible only just behind cardines.

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

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

Prothorax ( Figs. 42–43 View FIGURES 42 – 45 , 46, 48 View 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. 42 View FIGURES 42 – 45 ). Sides of pronotum mostly with thin setae, only anteroventral parts of hypomera with thick bristles ( Fig. 43 View FIGURES 42 – 45 ).

Prosternum ( Fig. 43 View FIGURES 42 – 45 ) with moderately short basisternal part ( Fig. 43 View FIGURES 42 – 45 ; bst) indistinctly demarcated from procoxal cavities ( Fig. 43 View FIGURES 42 – 45 ; pcc); median part of sternum slightly raised but not carinate; procoxal sockets ( Fig. 43 View FIGURES 42 – 45 ; pcs) open; hypomera ( Fig. 43 View 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. 43 View FIGURES 42 – 45 ; hyr) incomplete, visible only along anterior margins of adcoxal parts of hypomera; pronotosternal sutures ( Fig. 43 View FIGURES 42 – 45 ; nss) entire.

Mesocutellum ( Fig. 44 View FIGURES 42 – 45 ; scl2) subtriangular, in intact specimens hidden by posterior margin of pronotum overlapping with elytral base; mesoscutoscutellar suture present.

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

Metaventrite ( Fig. 45 View FIGURES 42 – 45 ; v3) subrectangular, anteriorly fused with mesoventrite, posteriorly moderately deeply bisinuate and with broad, shallowly emarginate metaventral intercoxal process ( Fig. 45 View FIGURES 42 – 45 ; mtvp); anteriorly with short and narrow anterior metaventral process ( Fig. 45 View FIGURES 42 – 45 ; amvp). Metanepisterna and metepimera narrow.

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

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

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

Legs ( Figs. 46, 48 View 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. 49–56 View FIGURES 49 – 52 View 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. 194 View 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 2012c). 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 .