Indomicrus, Jałoszyński, 2020

Jałoszyński, Paweł, 2020, Two new Oriental genera of Cephenniini (Coleoptera: Staphylinidae: Scydmaeninae), Zootaxa 4718 (3), pp. 423-435 : 429-430

Indomicrus gen. n.

Type species: Indomicrus chera sp. n. (here designated).

Diagnosis. Indomicrus differs from all remaining Cephenniini in a combination of characters: antenna with 11 antennomeres and symmetrical club; head with frontal glands; submentum vestigial; maxillary palpomere IV buttonshaped; pronotum lacking antebasal pits, foveae, groove and setose glandular openings; anterior pronotal corners well-defined and projecting anterad; prothorax with one pair of posterolateral internal ‘cavities’; basisternal part of prosternum shorter than coxal part; notosternal sutures complete; prosternal process strongly elevated, projecting beyond ventral margins of procoxae, with poorly marked anterior tip, with posterior tip directed ventroposterad; procoxal cavities closed by massive posterolateral lobes of coxal part of prosternum, each firmly fused with postcoxal portion of hypomeron; mesoscutellar shield with irregular arcuate row of foveate punctures; each elytron with one asetose rudiment of basal fovea, distinct humeral denticle but lacking humeral carina; mesoventral intercoxal process broad, with weakly elevated, diffuse median carina, with well-defined posterior lateral arms extending to sides of metaventrite as posterior carinae of mesocoxal rests; metaventral intercoxal process subtrapezoidal and narrow; abdominal sternites IV–VII with foveate punctures along posterior margins; aedeagus with symmetrical median lobe, asymmetrical endophallus and free parameres.

Description. Body ( Figs 20–21 ) suboval, strongly convex, covered with basic vestiture of short and dense setae and additionally with sparse, several times longer macrosetae.

Head capsule ( Figs 23–25 ) short and broad, in intact beetles tilted so strongly that plane of vertex is nearly perpendicular to the long body axis; frons ( Fig. 23 ; fr) and vertex ( Fig. 23 ; vt) confluent, together about as long as broad, convex; supraantennal tubercles indistinct; frons with small frontal glands ( Fig. 23 ; fg) visible only in transparent mounts under compound microscope; eyes moderately large, coarsely faceted, strongly convex; gular plate ( Fig. 25 ; gp) large, transverse, with sharply marked gular sutures ( Fig. 25 ; gs) and strongly transverse reticulate microsculpture and additionally with large, oval punctures; posterior tentorial pits indiscernible; submentum ( Fig. 25 ; smn) vestigial, with pair of tiny lateral setae. Mentum ( Fig. 25 ; mn) rectangular, weakly transverse, with pair of lateral anterior setae and inversely V-shaped ridge in anterior half; prementum ( Fig. 25 ; pmn) short, largely membranous, with an unknown number of paired suckers, labial palps minute and moderately broadly separated, inserted at sides of prementum, with palpomere I largest, slightly longer than broad, palpomere II distinctly shorter and narrower than I, slightly elongate, palpomere III much narrower and much longer than II, rod-like with narrowed apex, about 3 × as long as broad. Maxilla ( Fig. 25 ) with conspicuously large cardines, subtrapezoidal basistipes bearing two lateral submedian setae, elongate palpifer, elongate lacinia and galea, each with sparse and thick mesal setae; maxillary palp with minute palpomere I ( Fig. 25 ; mxp1), strongly elongate, slightly clavate palpomere II ( Fig. 25 ; mxp2), strongly broadened palpomere III which is about twice as long as broad and has truncate apex ( Fig. 25 ; mxp3), palpomere IV broad and very short, button-like ( Fig. 25 ; mxp4). Mandibles ( Figs 23, 25 ) symmetrical, rela- tively long, each with subquadrate basal portion and long, slender, only slightly curved distal tooth, setose prostheca absent. Labrum ( Fig. 23 ; lbr) short and strongly transverse, with indistinctly concave anterior margin and covered with symmetrically distributed dorsal setae, additionally with large translucent marginal velum ( Fig. 23 ; vl), which is broader than sclerotized portion of labrum and asetose.

Antennae ( Figs 20–21 , 26 ) long and slender, composed of 11 antennomeres, club symmetrical and dimerous.

Pronotum ( Figs 20–21 , 29 ) in dorsal view of whole specimen appears semioval ( Figs 20–21 ), but its shape is rectangular with rounded sides; anterior margin shallowly but distinctly concave; anterior pronotal corners broadly subtriangular, blunt and distinctly projecting anterad; lateral margins rounded, forming complete, microserrated lateral carinae ( Fig. 29 ; lpc); posterior corners well-defined, obtuse-angled, blunt; posterior margin arcuate. Pronotum lacking antebasal pits, foveae, groove or setose glandular openings; prothorax with a pair of posterolateral internal ‘cavities’ ( Fig. 28 ; ic) visible only in transparent mounts.

Prosternum ( Figs 22 , 28 ) with basisternal portion ( Fig. 28 ; bst) much shorter than coxal part; prosternal process ( Figs 28–29 ; psp) in ventral view subtriangular with indistinct anterior tip, in lateral view ( Fig. 29 ) subtriangular and strongly elongate, elevated ventrad beyond procoxae, strongly bent posterad and with serrated anteroventral margin; notosternal sutures ( Fig. 28 ; nss) complete; procoxal cavities ( Fig. 28 ; pcc) broadly closed by posterolateral lobes of prosternum that are fused with postcoxal portions of hypomera; hypomeral ridges ( Fig. 28 ; hyr) nearly complete but relatively diffuse on SEMs ( Fig. 22 ); hypomera outside hypomeral ridges broad and concave; inner portion of each hypomeron behind procoxal cavity covers profurcal fovea and forms small lobe that in lateral view is visible as projection directed posteroventrad behind prosternal process ( Fig. 29 ).

Mesonotum (not shown) subrectangular, with subtriangular, transverse mesoscutellar shield exposed between elytral bases ( Fig. 21 ) and bearing irregular transversely arcuate (posteriorly convex) row of small foveate punctures, scutoscutellar suture not visible on dorsal surface, but discernible in transparent mounts; mesoscutum strongly transverse.

Elytra ( Figs 20–21 ) oval, each with humeral denticle and one asetose rudiment of basal elytral fovea ( Fig. 21 ; bef); apices of elytra rounded together.

Mesoventrite ( Figs 22 , 30 ) with mesoventral intercoxal process ( Fig. 30 ; msvp) conspicuously broad and weakly elevated, with diffuse median carina anteriorly connected to anterior ridge of ventrite; posterolateral arms present. Lateral impressions functioning as procoxal rests ( Fig. 30 ; pcr) present, asetose, subtriangular, separated at middle and with all margins well-defined. Mesoventrite lacking foveae.

Metanotum (not shown) largely membranous, short, but with well-defined alacristae posteriorly reaching behind middle of metascutum.

Hind wings absent.

Metaventrite ( Figs 22 , 30 ) short, slightly transverse; posterior margins of mesocoxal rests carinate; sides weakly rounded, posterior margin weakly concave at each metacoxa, with relatively narrow and short, subtrapezoidal metaventral intercoxal process ( Fig. 30 ; mtvp). Admetacoxal region at each side with irregular row of foveate punctures along anterior metacoxal margins, obscured by similar punctures distributed on entire ventrite. Metanepisterna and metepimera narrow.

Metendosternite (= metafurca) ( Fig. 30 ) with short and broad stalk and divergent lateral furcal arms ( Fig. 30 ; lfa) with adjacent bases (V-shaped).

Legs moderately long and slender; pro- and mesocoxae oval, metacoxae strongly transverse; all trochanters short and subtriangular; all femora distinctly clavate; tibiae broadening distad, with protibia ( Fig. 27 ) in both sexes particularly strongly broadened and with several flattened digitiform projections; tarsi short.

Abdominal sternites ( Figs 22 , 31 ) unmodified, except for posterior rows of foveate punctures on sternites IV–VII.

Aedeagus ( Figs 32–35 ) elongate, with symmetrical median lobe and asymmetrical endophallus, diaphragm present, circular, sub-basal on ventral wall; parameres slender, with apical setae, parameral base with lateral lobes.

Distribution and composition. Indomicrus is represented by one species known to occur in southern India.

Etymology. The name Indomicrus combines the prefix Indo - derived from the country name India, with the suffix - micrus, to emphasize the similarity to other members of the ‘ Cephennomicrus group’ of genera. Gender masculine.

Remarks. Indomicrus is placed within the ‘ Cephennomicrus group’ of genera on the basis of the button-like maxillary palpomere IV and the presence of frontal glands. Preliminary results of a phylogenetic analysis indicate that this genus may be a sister group for Trichokrater + Trurlia (Jałoszyński, in prep.). Indomicrus differs from Eutheimorphus , Trichokrater , Trurlia , Clavomicrus , Cephennula , Lathomicrus , Foveomicrus, and Cephennomicrus in the internal ‘cavities’ in the prothorax; from Cephennococcus and Pomphopsilla (among others) in complete notosternal sutures (which are partly obliterated in Cephennococcus and Pomphopsilla ).

Figures

FIGURES 20–22. Indomicrus chera gen. & sp. n. Dorsal (20–21) and ventral (22) habitus. Abbreviations: bef, basal elytral foveae; msvp, mesoventral process; mtvp, metaventral process; pcr, procoxal rest; psp, prosternal process.

FIGURES 23–30. Indomicrus chera gen. & sp. n. Head in dorsal (23) and ventral (24–25) views; right antenna in dorsal view (26); right protarsus and apex of tibia in dorsal view (27); prothorax in ventral (28) and lateral (29) view; pterothorax in ventral view (30). Abbreviations: bst, basisternum; fg, frontal gland; fr, frons; gp, gular plate; gs, gular suture; hyr, hypomeral ridge; ic, internal cavity; lbr, labrum; lp, labial palp; lpc, lateral pronotal carina; md, mandible; mn, mentum; mscc, mesocoxal cavity; msvp, mesoventral process; mtvp, metaventral process; mxp1–4, maxillary palpomere I–IV; nss, notosternal suture; pcc, procoxal cavity; pcr, procoxal rest; pmn, prementum; psp, prosternal process; smn, submentum; vl, velum; vt, vertex; lfa, lateral furcal arm.

FIGURES 31–35. Indomicrus chera gen. & sp. n. Abdominal sternites III–VII in ventral view (31); aedeagus in ventral (32, 34) and lateral (33, 35) views. Arrows showing rows of foveate punctures.