Liliputella, Jałoszyński, Paweł, 2016

Jałoszyński, Paweł, 2016, Liliputella, a new genus of microscopic, wingless and blind Scydmaenini of the Bismarck Islands (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4093 (1), pp. 135-142 : 136-139

Liliputella gen. nov.

Type species: Liliputella microscopica sp. n. (here designated).

Diagnosis. A genus of Scydmaenini differing from all other taxa of this tribe in large ventral cavity behind mouthparts; pronotum and elytra lacking any traces of pits and impressions; and aedeagus with slender, free parameres.

General body shape ( Fig 1 ) elongate, body strongly flattened, distinctly but not deeply constricted between head and pronotum and between pronotum and elytra; appendages short and robust; vestiture composed of short setae; pigmentation of cuticle light brown.

Head capsule ( Figs 1 , 3 ) divided by occipital constriction into large anterior and small posterior part ('neck' region), posterior part retracted into pronotum. 'Neck' region distinctly narrower than vertex, short and subcylindrical; narrowest site of occipital constriction ( Fig. 3 ; occ) much wider than half HW. Anterior part of head ( Figs 1 , 3 ) subtriangular and rounded, broadest in posterior half. Compound eyes absent; vertex posteriorly slightly impressed medially, anteriorly confluent with subtriangular frons; clypeus and mouthparts shifted to the ventral surface of head ( Fig. 3 ), which is flattened. Antennal insertions located on ventral surface of strongly declined frons, nearly touching at middle. Gular plate ( Fig. 3 ; gp) subtrapezoidal with rounded sides, gular sutures ( Fig. 3 ; gs) distinct, sharply marked and anteriorly meeting at middle. Posterior tentorial pits not visible. Median area between gular plate and mouthparts occupied by large transverse and deep ventral cavity ( Fig. 3 ; vc) surrounded by dense setae. Head with indistinct microsculpture: faint transverse cells on gular plate and polygonal reticulation of anterolateral area of ventral surface of 'neck'.

Mouthparts ( Fig. 3 ) in the studied specimen only partly exposed, details of clypeus, labrum, mandibles and prementum not visible because of unusual ventral position of mouthparts and tightly closed mandibles. Submentum strongly declining into ventral cavity, not visible in ventral view, but its position marked by pair of setae, which in Scydmaeninae are typically inserted near middle or in anterior region of submentum. Mentum ( Fig. 3 ; mn) subhexagonal and elongate, broadest in front of middle. Prementum largely obscured by maxillae; labial palps seem minute and their insertions broadly separated; cardo ( Fig. 3 ; cd) transverse; basistipes ( Fig. 3 ; bst) small and triangular, with one seta; mediostipes ( Fig. 3 ; mst) elongate; lacinia and galea ( Fig. 3 ; lac, gal) elongate, each with dense distal setae; palpifer ( Fig. 3 ; ppf) large, with short seta. Maxillary palps ( Fig. 3 ; mxpi) short, palpomere I slightly longer than broad; palpomere II clavate, broad and only about 2.5× as long as broad; palpomere III pedunculate, broad and about twice as long as broad, broadest near middle; palpomere IV minute, dome-shaped.

Antennae ( Figs 1 , 3, 4 ) moderately slender and moderately long, gradually thickened distally; scape with shallow and broad ventral and dorsal apical emarginations; flagellomeres relatively compactly assembled.

Prothorax ( Figs 1 , 5–6 ) in dorsal view ( Fig. 1 ) indistinctly bell-shaped, broadest in front of middle; anterior corners indistinct, posterior corners obtuse-angled and blunt. Pronotum lacking any carinae, pits, grooves or impressions. Prosternum ( Fig. 6 ) nearly half as long as pronotum, with basisternal part ( Fig. 6 ; bst) very long, several times longer than coxal part and distinctly demarcated from procoxal cavities ( Fig. 6 ; pcc) by double carina; prosternal intercoxal process ( Fig. 6 ; psp) subtriangular and weakly elevated; procoxal sockets ( Fig. 6 ; pcs) broadly open. Hypomera ( Fig. 6 ; hy) elongate and confluent with sides of pronotum, lacking hypomeral ridges or grooves; notosternal sutures absent.

Mesothorax ( Figs 5, 7 ). Mesonotum with remarkably large, triangular and strongly transverse scutellum ( Fig. 5 ; scl2), only its tip visible between elytral bases.

Mesoventrite ( Fig. 7 ) short, much broader than long, lacking demarcated anterior ridge; procoxal rests weakly defined and hidden under procoxae ( Fig. 7 ); mesoventral intercoxal process ( Fig. 7 ; msvp) moderately broad, nearly parallel-sided, weakly elevated; mesocoxal sockets ( Fig. 7 ; mscs) located ventromesally on mesocoxal projections ( Fig. 7 ; mcp) and in ventral view partly exposed; mesofurcal foveae ( Fig. 7 ; msff) small and located near anterior margins of mesocoxal cavities ( Fig. 7 ; mscc). Prepectus ( Fig. 7 ; pre) large. Median area of mesoventrite in front of mesocoxae with polygonal reticulation.

Metathorax. Metaventrite ( Fig. 7 ) shorter than mesoventrite, strongly transverse, anteriorly fused with mesoventrite, lateral margins arcuate, lateral (admetacoxal) parts of posterior margin strongly concave, at middle posterior margin broadly concave and forming broad and short metaventral intercoxal process ( Fig. 7 ; mtvp). Metanepisterna concealed under elytra. Anteriorly and laterally metaventrite covered with polygonal reticulation; pattern of connected and raised edges of cells forms pair of indistinct lateral carinae extending from each mesocoxal projection up to metacoxa.

Metafurca (metendosternite) ( Fig. 7 ) with broadly separated insertions of lateral furcal arms ( Fig. 7 ; lmfa).

Elytra ( Figs 1 , 5, 7 ) elongate, lacking basal foveae, impressions or humeral calli, with distinct humeral denticles ( Figs 5, 7 ; hd).

Metathoracic wings absent.

Abdomen ( Fig. 7 ) longer than meso- and metaventrite together; sternite III (first visible) nearly as long as IV– VII combined, its anterior intermetacoxal region distinctly reticulate; suture between sternites VII and VIII distinct. Pygidium not exposed; propygidium lacking median impression.

Legs ( Figs 1 , 6–7 ) short and robust; pro- and mesocoxae subconical; metacoxae oval and transverse; all trochanters subtriangular and short; all femora gradually and weakly clavate; tibiae flattened, broadened distally; tarsi strikingly short, tarsomeres I and V elongate, II–IV subquadrate or transverse.

Aedeagus ( Figs 8–9 ) with symmetrical median lobe, elongate; diaphragm located sub-basally on ventral wall; flagellum looped; parameres free and slender, with apical setae.

Etymology. Liliputella is derived from the Liliput nation of Gulliver's Travels by Jonathan Swift; the name refers to the tiny body of this beetle. Gender feminine.

Remarks. The structure of maxillary palpomeres clearly places Liliputella in Scydmaenini . Indeed, in a preliminary phylogenetic analysis, Liliputella was placed as a sister group to Pseudoeudesis , clearly within Scydmaenini (results not shown).

Figures

FIGURES 1 – 2. Liliputella microscopica gen. & sp. nov. Dorsal habitus of holotype male (1) and distribution (2; indicated by arrow).

FIGURES 3 – 9. Liliputella microscopica gen. & sp. nov. Head in ventral view (3); left antenna in ventral view (4), prothorax and elytral base in dorsal view (5), prothorax in ventral view (6), pterothorax in ventral view (7), aedeagus in ventral (8) and lateral (9) views. Abbreviations: bst, basisternal part of prosternum; bst, basistipes; cd, cardo; fo, foramen occipitale; gal, galea; gp, gular plate; gs, gular suture; hd, humeral denticle; lac, lacinia; lmfa, lateral metafurcal arm; mcp, mesocoxal projection; md, mandible; mn, mentum; mscc, mesocoxal cavity; mscs, mesocoxal socket; msff, mesofurcal fovea; mst, mediostipes; msvp, mesoventral intercoxal process; mtvp, metaventral intercoxal process; mxp, maxillary palp; occ, occipital constriction; pcc, procoxal cavity; pcs, procoxal socket; pff, profurcal fovea; ppf, palpifer; pre, prepectus; psp, prosternal process; scl 2, mesocutellum; st 3 − 8, sternite III − VIII; vc, ventral cavity.