Leascydmus Jałoszyński, 2014, gen. n.
Creators: name: Jałoszyński, Paweł
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Leascydmus

description: Leascydmus gen. n.
Type species: Scydmaenus simplicicornis Lea, 1910: 185 (here designated).
Diagnosis. Body (Figs. 46–48) elongate and strongly convex; head (Fig. 37) short and convex; vertex (Fig. 37; 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; 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; hr) rudimentary, indistinctly marked only just behind cardines; posterior tentorial pits (Fig. 38; ptp) elongate and located distinctly in front of transverse groove demarcating 'neck' ventrally; submentum (Fig. 38; smn) without lateral sutures; each mandible with apical tooth sharply demarcated from basal part and densely setose prostheca (Fig. 40; pst), subapical teeth absent; maxillary palpomeres III and IV (Fig. 41; mxp3–4) slender, strongly elongate; pronotum (Figs. 42, 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; nss), without intercoxal process or carina; procoxal sockets (Fig. 43; pcs) narrowly open; prothoracic hypomera (Fig. 43; hy) with large internal (adcoxal) parts demarcated from sides of pronotum by incomplete hypomeral ridges (Fig. 43; hyr) developed only anteriorly; sides of prothorax (Fig. 43) 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; ar) without posterior median projection; mesoventral process (Fig. 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; vlf, dlf) present; anterior metaventral process (Fig. 45; amvp) present; metaventral intercoxal process (Fig. 45; mtvp) broadly separating metacoxae, without spines, with shallowly concave posterior margin; each elytron with two asetose rudiments of basal foveae (Fig. 44; bef) not connected by groove and barely discernible in dry-mounted specimens; aedeagus (Figs. 49–56) with free and slender parameres.
Description. Body (Figs. 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, 46, 48) with occipital constriction (Fig. 37; 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; tm) long and strongly curved posteromesally, without bristles; vertex (Fig. 37; vt) transverse, uniformly convex, not projecting dorso-caudad, with evenly rounded and convex posterior margin sharply demarcated from occiput; frons (Fig. 37; 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) 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) symmetrical, subtriangular, each with broad base and curved, rapidly narrowing and pointed apical part; prostheca (Fig. 40; pst) present, with dense thin setae along mesal mandibular margin, slightly expanding onto dorsal surface of mandible and reaching mandibular base. Maxilla (Fig. 41) composed of small cardo (Fig. 41; cd) bearing several setae; subtriangular basistipes (Fig. 41; bst); elongate mediostipes (Fig. 41; mst); elongate galea (Fig. 41; gal) and lacinia (Fig. 41; lac); large, elongate palpifer (Fig. 41; pfp); and strongly elongate and moderately large maxillary palp (Fig. 38; mxp) composed of elongate palpomere I (Fig. 41; mxp1), strongly elongate, clavate and slender palpomere II (Fig. 41; mxp2), large and strongly elongate palpomere III (Fig. 41; mxp3) broadest near distal third, and small, slender, subconical and pointed palpomere IV (Fig. 41; mxp4). Labium (Fig. 38) with large submentum (Fig. 38; smn) not demarcated posteriorly from gular plate and not demarcated laterally from postcardinal parts of hypostomae; subrectangular and transverse mentum (Fig. 38; mn); and relatively long prementum (Fig. 38; pmn) bearing narrowly separated at bases long 3-segmented labial palps and ligula with single median bristle. Hypostomal ridges (Fig. 38; hr) superficial and visible only just behind cardines.
Gular plate (Fig. 38; gp) large and subtrapezoidal, with rapidly narrowed anterior portion; gular sutures (Fig. 38; gs) superficial; posterior tentorial pits (Fig. 38; ptp) narrow and arcuate, located clearly in front of transverse groove ventrally demarcating 'neck region'.
Antennae (Figs. 46, 48) long and slender, gradually but only slightly thickening distally; antennomere XI conspicuously long.
Prothorax (Figs. 42–43, 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). Sides of pronotum mostly with thin setae, only anteroventral parts of hypomera with thick bristles (Fig. 43).
Prosternum (Fig. 43) with moderately short basisternal part (Fig. 43; bst) indistinctly demarcated from procoxal cavities (Fig. 43; pcc); median part of sternum slightly raised but not carinate; procoxal sockets (Fig. 43; pcs) open; hypomera (Fig. 43; hy) elongate, each divided into broad lateral part confluent with pronotum and narrower but still broad internal (adcoxal) part; hypomeral ridges (Fig. 43; hyr) incomplete, visible only along anterior margins of adcoxal parts of hypomera; pronotosternal sutures (Fig. 43; nss) entire.
Mesocutellum (Fig. 44; scl2) subtriangular, in intact specimens hidden by posterior margin of pronotum overlapping with elytral base; mesoscutoscutellar suture present.
Mesoventrite (Fig. 45) with narrow and indistinctly demarcated anterior ridge (Fig. 45; ar); mesoventral intercoxal process (Fig. 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; pcr) filled with short setae (= setose impressions) but without asetose impressions; mesanepisternum with moderately long prepectus (Fig. 45; pre), sides of mesoventrite with two pairs of narrow, deep and setose ventrolateral and dorsolateral foveae (Fig. 45; vlf, dlf); mesocoxal projections (Fig. 45; mcp) prominent, with mesocoxal sockets located on their mesal surface and not visible in ventral view.
Metaventrite (Fig. 45; v3) subrectangular, anteriorly fused with mesoventrite, posteriorly moderately deeply bisinuate and with broad, shallowly emarginate metaventral intercoxal process (Fig. 45; mtvp); anteriorly with short and narrow anterior metaventral process (Fig. 45; amvp). Metanepisterna and metepimera narrow.
Metafurca (Fig. 45) with short stalk and divergent lateral furcal arms (Fig. 45; lmfa).
Elytra (Figs. 44, 46, 48) oval, each with two asetose rudiments of basal foveae (Fig. 44; bef) barely discernible in dry-mounted specimens; each humerus with small and blunt but distinct humeral denticle (Fig. 42; hd); subhumeral lines absent.
Hind wings well-developed, about twice as long as elytra.
Legs (Figs. 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) 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).
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.
description: Published as part of Jałoszyński, Paweł, 2014, ' The curse of Horaeomorphus ': taxonomy of misplaced Australian Cyrtoscydmini (Coleoptera: Staphylinidae: Scydmaeninae), pp. 1-76 in Zootaxa 3828 (1) on pages 18-21, DOI: 10.11646/zootaxa.3828.1.1, http://zenodo.org/record/286513