Scydmepitoxis, Jałoszyński, Paweł, 2014

Jałoszyński, Paweł, 2014, Scydmepitoxis gen. n., a new genus of Cyrtoscydmini (Coleoptera: Staphylinidae: Scydmaeninae) from Australia, Zootaxa 3866 (2), pp. 289-296 : 290-295

Scydmepitoxis gen. n.

Type species: Scydmepitoxis paradoxa (here designated).

Diagnosis. Male and female: head with distinct occipital constriction as narrow as about half width of vertex; ‘neck region’ much narrower than vertex; frontoclypeal groove present; eyes adjacent to antennal cavities; tempora long; vertex not projected dorsocaudad, with nearly straight posterior margin; submentum not demarcated laterally by sutures; hypostomal ridges distinct and nearly reaching posterior tentorial pits, which are elongate and located in front of transverse impression demarcating ventrally ‘neck region’; posterior margin of vertex, tempora and sides of pronotum with thick bristles; antennae gradually thickened distally; pronotum strongly and abruptly constricted in posterior third, with four antebasal pits, without lateral edges or carinae; basisternal portion of prosternum rudimentary; procoxae contiguous; pronotosternal sutures complete; procoxal sockets broadly closed; hypomeral ridges complete; each elytron with two asetose rudiments of basal foveae; mesothorax with ventrolateral foveae, without dorsolateral foveae; mesoventral intercoxal process barely marked between mesocoxae, indistinct and with diffused lateral margins; mesanepisterna broad and largely visible in ventral view laterally to mesocoxal projections; metaventral intercoxal process broad and short, subtrapezoidal, with arcuate median emargination. Male: aedeagus symmetrical, with free parameres and distinct sclerotized endophallus. Female: spermatheca globular, located deeply in metathorax.

Description. Body ( Fig. 1 ) elongate and convex, with distinctly marked constrictions between head, prothorax and elytra, BL 1.48–1.50 mm; cuticle glossy, brown and setose.

Head capsule ( Fig. 3 ) with anterior part (in front of occiput) nearly pentagonal, with moderately large and weakly projecting bean-shaped eyes (larger in males, smaller in females); occipital constriction distinct and as narrow as about half width of vertex; ‘neck region’ broadening posteriorly and slightly wider than half width of vertex; tempora longer than eyes, distinctly convergent posteriorly; vertex broader than long, convex, not projecting dorsocaudally, with nearly straight posterior margin; frons posteriorly confluent with vertex, with subtrapezoidal anterior part abruptly lowering toward clypeus; frontoclypeal transverse groove present; antennal insertions broadly separated. Tempora and posterior margin of vertex covered with thick bristles.

Gular plate ( Fig. 3 ; gp) large and distinctly narrowing anteriorly; gular sutures ( Fig. 3 ; gs) superficial; posterior tentorial pits ( Fig. 3 ; ptp) exposed, strongly elongate and located distinctly in front of transverse impression demarcating ‘neck region’ ventrally.

Labrum transverse with rounded anterior margin. Mandibles ( Fig. 3 ; md) only partly visible in available specimen, each with broad basal part and slender apical tooth with tiny subapical denticle at base; prostheca not visible. Each maxilla ( Fig. 3 ) with subtriangular basistipes ( Fig. 3 ; bst), broad mediostipes ( Fig. 3 ; mst) elongate galea ( Fig. 3 ; gal) and lacinia ( Fig. 3 ; lac) and moderately long maxillary palp ( Fig. 3 ; mxp) composed of distinctly elongate palpomere I, strongly elongate, pedunculate palpomere II, broad palpomere III broadest near apex, and elongate and slender subconical and pointed palpomere IV.

Labium ( Fig. 3 ) with transverse submentum ( Fig. 3 ; smn) not demarcated laterally from postcardinal parts of hypostomae; subtrapezoidal mentum ( Fig. 3 ; mn); and short prementum ( Fig. 3 ; pmn) bearing small 3-segmented labial palps and median subtriangular ligula ( Fig. 3 ; lg) with two pairs of tiny setae. Hypostomal ridges ( Fig. 3 ; hr) long, extending posteromesally nearly up to posterior tentorial pits, not connected in middle.

Antennae ( Fig. 1 ) long and slender, gradually and only slightly thickening distally.

Pronotum ( Fig. 4 ) in dorsal view hourglass-shaped with long anterior and short posterior part; anterior margin weakly arcuate; anterior corners distinct, strongly obtuse; sides in anterior half rounded; posterior constriction deep and narrow; sides of posterior part of pronotum behind constriction rounded; posterior corners well-marked but blunt, strongly obtuse; posterior margin weakly bisinuate. Pronotum with four small but deep and sharply marked circular antebasal pits ( Fig. 4 ; abp). Sides of pronotum with thick bristles directed lateroposteriorly, on each anterolateral margin of constriction forming dense brush; sides of posterior part of pronotum with two to three bristles directed anterolaterally.

Prosternum ( Fig. 5 ) with short, almost rudimentary basisternal part ( Fig. 5 ; bst) indistinctly demarcated from procoxal cavities ( Fig. 5 ; pcc); median part of sternum without prosternal intercoxal process, only slightly subtriangularly raised in anteromedian region; procoxal sockets ( Fig. 5 ; pcs) broadly closed by lateral lobes of prosternum; hypomera ( Fig. 5 ; hy) elongate, each divided into broad lateral part and narrow internal (adcoxal) part, internal part fused with prosternum in narrow area adjacent to anterolateral margin of procoxal socket and bearing circular impression with dense setal brush near posterior margin; pronotosternal sutures ( Fig. 5 ; nss) and hypomeral ridges ( Fig. 5 ; hyr) complete.

Mesonotum subtriangular, with subtriangular and posteriorly rounded mesoscutellum and distinct mesoscutoscutellar suture. Mesoscutellum not visible between bases of elytra in intact specimens.

Mesoventrite ( Figs. 6–7 ) with narrow and indistinctly demarcated anterior ridge ( Figs. 6–7 ; ar); mesoventral intercoxal process ( Figs. 6–7 ; msvp) barely marked, developed as low (i.e., weakly projecting ventrally) and diffused subtriangular convexity between mesocoxae, not separating coxae; area between process and anterior ridge weakly convex and largely setose, without demarcated setose or asetose impressions or procoxal rests; mesanepisternum with indistinct prepectus but with strongly laterally expanded posterior portion well-visible in ventral view; mesepimeron not visible in ventral view; sides of mesothorax with deep ventrolateral foveae ( Figs. 6–7 ; vlf); additionally anteromedian portion of mesoventrite slightly raised and at each side with fovea directed mesally; mesocoxal projections ( Figs. 6–7 ; mcp) with mesocoxal sockets ( Figs. 6–7 ; mscs) located on their mesoventral surface, without projecting posterior lobes.

Metaventrite subquadrate, anteriorly fused with mesoventrite, posteriorly shallowly bisinuate and with moderately broad and short median subtriangular metaventral intercoxal process ( Fig. 6 ; mtvp) bearing arcuate median emargination. Metanepisterna and metepimera narrow.

Metafurca ( Fig. 6 ) with very short and broad stalk and divergent lateral furcal arms ( Fig. 6 ; lmfa).

Elytra ( Fig. 1 ) oval, each with two rudimentary and asetose basal foveae barely discernible in transparent mounts; humeral calli well-marked and developed as longitudinal protuberances; elytral apices rounded, unmodified.

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

Legs ( Figs. 1 , 5–6 ) moderately long and slender; pro- and mesocoxae oval, metacoxae strongly transverse; all trochanters short; all femora weakly clavate; tibiae slender; tarsi moderately long.

Abdominal sternites ( Fig. 6 ) unmodified, suture between VII and VIII indistinct in middle.

Aedeagus ( Figs. 8–9 ) elongate, relatively lightly sclerotized and thin-walled, symmetrical, with free and slender parameres devoid of apical setae, and with elongate and moderately darkly sclerotized internal armature.

Spermatheca ( Fig. 6 ; sp) globular, thick-walled, located deeply in metathorax.

Distribution and composition. Scydmepitoxis is represented by S. paradoxa sp. n. described below and known from the easternmost part of Australia (NE New South Wales) ( Fig. 2 a) and an undescribed species known only from a single female deposited at ANIC and collected by a flight intercept trap at 875 m on Mount Spec in Queensland ( Fig. 2 b).

Etymology. The name Scydmepitoxis is composed of “ scydm -” (as in Scydmaeninae ) and the Latin noun epitoxis, meaning “the notch in a catapult, in which the cord lay”. The name refers to the laterally notched prothorax. Gender feminine.

Remarks. This remarkable new genus can be distinguished from all Cyrtoscydmini on the basis of the strongly constricted prothorax. Scydmepitoxis also differs from Australian genera in a number of other characters (genera listed in alphabetic order, Psepharobius King omitted, see discussion in Jałoszyński (2014b):

- from Euconnus : in the head nearly pentagonal, with tempora rapidly bent mesally in the posterior third (‘anthiciform’); the mesoventral intercoxal process barely marked, not keel-shaped and not separating mesocoxae; the basal elytral foveae rudimentary;

- from Horaeomorphus : in the supraantennal tubercles not accompanied by pits; the posterior tentorial pits not adjacent to the transverse groove demarcating the ‘neck region’ ventrally and not located between posterior portions of the hypostomal ridges; the pronotum without the median antebasal pit; the prosternum without prosternal intercoxal carina; the mesoventral intercoxal process barely marked, not separating mesocoxae; the ventrolateral mesothoracic foveae present; long posterior spines of the metaventral intercoxal process absent; basal elytral foveae rudimentary and not connected by a U-shaped groove;

- from Leascydmus: in the ‘anthiciform’ head; the tempora, vertex and sides of pronotum with bristles; the hypostomal ridges long; the procoxal sockets broadly closed; the pronotum with distinct antebasal pits; the mesoventral intercoxal process barely marked, not separating mesocoxae; the dorsolateral mesothoracic foveae absent; the metacoxae nearly contiguous; the aedeagus with symmetrical internal armature;

- from Microscydmus : in the antennae without delimited club; the occipital constriction much narrower than vertex; the posterior tentorial pits elongate and located in front o f transverse impression demarcating the ‘neck region’ ventrally; the gular plate with a rapidly narrowed anterior part and not demarcated from submentum; the prosternum without intercoxal carina; the mesoventral intercoxal process indistinct, not carinate; the mesothorax with ventrolateral foveae; the metaventral intercoxal process without long posterior spines; each elytron with rudiments of two basal foveae;

- from Palaeoscydmaenus : in the tempora long and rapidly bent mesally; the occipital constriction much narrower than vertex; the submentum not demarcated laterally by sutures; the gular plate with rapidly narrowed anterior part and not demarcated from submentum; the posterior tentorial pits exposed; the tempora, vertex and sides of pronotum with bristles; the pronotum with antebasal pits and without a groove; the hypomeral ridges present; the procoxal sockets closed; two basal elytral foveae present; the median part of mesoventrite between posteromedian projection of anterior ridge and anterior margins of mesocoxae not carinate; the mesothorax with ventrolateral foveae; the metaventral intercoxal process emarginate, without narrow notch; the aedeagus symmetrical;

- from Penicillidmus: in the antennae without delimited club; the occipital constriction much narrower than vertex; the posterior tentorial pits elongate and located in front of transverse impression demarcating the 'neck region' ventrally; the gular plate with rapidly narrowed anterior part and not demarcated from the submentum; the head ventrally posterior to mouthparts without longitudinal and transverse carinae; the prosternum without intercoxal carina; the mesoventral intercoxal process indistinct, not carinate; the mesothorax with ventrolateral foveae; the metaventral intercoxal process without long posterior spines; each elytron with two rudiments of basal foveae;

- from Sciacharis (s. str.): in the basisternal part of prosternum rudimentary; the posteromedian projection of mesoventral anterior ridge not strongly elongate; the metaventral intercoxal process emarginate; the basal elytral foveae rudimentary;

- from Sciacharis (Magellanoconnus) : in the pronotum without median carina, without sublateral and lateral carinae and without antebasal transverse impressions; the basisternal part of prosternum rudimentary; the mesoventral intercoxal process indistinct, not carinate; the dorsolateral mesothoracic foveae absent; the metaventral intercoxal process narrow and therefore metacoxae nearly contiguous; the aedeagus with symmetrical internal armature;

- from Sciacharis (Maorinus) : in the ‘anthiciform’ head; the pronotum without sublateral carinae; basal elytral foveae rudimentary; the mesoventral intercoxal process not separating mesocoxae and not continuous with the posteromedian projection of anterior ridge; dorsolateral mesothoracic foveae absent; the metaventral intercoxal process emarginate and without narrow notch; the metendosternite with a short and broad stalk;

- from Sciacharoides: in the pronotum without antebasal transverse groove; the posteromedian projection of anterior mesoventral ridge not strongly elongate; the metaventral intercoxal process emarginate;

- from Scydmaenilla : in the ‘anthiciform’ head; the tempora and vertex with bristles; the occipital constriction much narrower than vertex; the submentum without lateral sutures; the pronotum without antebasal groove and without lateral carinae; the prosternum without intercoxal carina; the hypomera with hypomeral ridges; the posteromedian projection of mesoventral anterior ridge not elongate; the metaventral anterior process absent; the metaventral intercoxal process emarginate, without narrow notch;

- from Scydmaenozila: in the hypomeral ridges complete; the mesoventral intercoxal process barely marked, not separating mesocoxae; the dorsolateral mesothoracic foveae absent; the metendosternite with very short stalk; the basal elytral foveae rudimentary; the mesoventral intercoxal process indistinct; the ventrolateral foveae of mesothorax present;

- from Spinosciacharis: in the pronotum without median longitudinal carina and without sublateral carinae; the prosternum with the basisternal part much shorter than procoxal cavities; the posteromedian projection of anterior mesoventral ridge not extending posteriorly up to mesocoxal cavities; the anterior metaventral process absent; the metaventral intercoxal process emarginated and without a narrow notch; the metendosternite with a short and broad stalk; the metafemora in males unmodified; basal elytral foveae rudimentary;

- from Syndicus : in two terminal antennomeres clearly separated; the head 'anthiciform'; the posterior tentorial pits elongate and located in front of the transverse impression separating 'neck region' ventrally; the prosternum without intercoxal carina; the basal elytral foveae not connected by a U-shaped groove; the mesoventral intercoxal process indistinct and not carinate; the femora without dorsal femoral grooves.

Scydmepitoxis shares a number of characters with Sciacharis s. str. and Sciacharoides: the 'anthiciform' head with long tempora; bristles on tempora and prothorax; long hypostomal ridges; the submentum not demarcated laterally by sutures; posterior tentorial pits located anteriorly to the transverse impression demarcating the 'neck region' ventrally; procoxae contiguous; prothoracic hypomeral ridges complete or nearly complete; similarly shaped adcoxal portions of prothoracic hypomera; the presence of distinct ventrolateral mesothoracic foveae; and two asetose basal elytral foveae. It seems plausible that Scydmepitoxis is closely related to these genera.

Figures

FIGURES 1 – 2. Morphology and distribution of Scydmepitoxis gen. n. Dorsal habitus of Scydmepitoxis paradoxa sp. n., male holotype (1); distribution of S. paradoxa sp. n. (2 a) and Scydmepitoxis sp., undescribed species known from a female (2 b).

FIGURES 3 – 5. Morphology of Scydmepitoxis paradoxa sp. n., paratype female. Head in ventral view (3); prothorax and base of elytra in dorsal view (4); and prothorax in ventral view (5). Abbreviations: abp, antebasal pronotal pits; aest 2, mesanepisternum; bas, basisternal part of prosternum; bst, basistipes; cd, cardo; el, elytron; gal, galea; gp, gular plate; gs, gular suture; hr, hypostomal ridge; hy, hypomeron; hyr, hypomeral ridge; lac, lacinia; md, mandible; mn, mentum; mst, mediostipes; mxp, maxillary palpus; nss, pronotosternal suture; pcc, procoxal cavity; pcs, procoxal socket; pf, profurca; pmn, prementum; pn, pronotum; ppf, palpifer; smn, submentum.

FIGURES 6 – 9. Morphology of Scydmepitoxis paradoxa sp. n., paratype female (6 – 7) and holotype male (8 – 9). Pterothorax in ventral view (6); mesothorax in ventral view, setation omitted (7); aedeagus in ventral (8) and lateral (9) views. Abbreviations: aest 2, mesanepisternum; aest 3, metanepisternum; ar, anterior ridge; lmfa, lateral metafurcal arm; mcc, mesocoxal cavity; mcp, mesocoxal projection; mcs, mesocoxal socket; mff, mesofurcal fovea; msvp, mesoventral intercoxal process; mtvp, metaventral intercoxal process; sp, spermatheca; vlf, ventrolateral fovea.