Stenichnus andicola Franz, 2015

Jałoszyński, Paweł, 2015, Revision of Neotropical species of ant-like stone beetles misplaced in Stenichnus and Scydmoraphes (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4027 (2), pp. 253-269 : 254-258

Sciacharis (incertae sedis) andicola (Franz) comb. n.

( Figs 1–8 , 28 )

Stenichnus (Cyrtoscydmus) andicola Franz, 1980a: 209 , fig. 196.

Material studied. Holotype ( BOLIVIA): ♂: three original labels ( Fig. 28 ): "Nebelwald b. / Comarapa, Peru [crossed out and corrected to Boliv.] / lg.H.Franz" with "SA143" on the reverse side [white, printed; correction and reverse handwritten], " Stenichnus / ( Cyrtoscydmus ) / ♂ andicola m. / det.H.Franz" [white, handwritten and printed], " Typus " [red, handwritten] ( NHMW). Paratypes: 3 ♀♀: same data as for holotype, but one with red handwritten "Allotypus" label and two remaining with yellow " PARATYPUS " identification labels ( NHMW).

Diagnosis. Male with modified metafemora: their dorsal (anterior in Fig. 1 ) margin in basal half bulging and femur near middle rapidly narrowing distally, posterior (dorsal in Fig. 1 ) surface of femur near middle with large shallow pit; female also has weakly concave dorsal femoral margin in the same region as male, although base of femur is not swollen.

Redescription. Body of male ( Fig. 1 ) strongly convex, elongate and relatively slender, with long appendages, BL 1.48 mm; cuticle moderately glossy, uniformly brown with slightly lighter legs, antennae and palps and darker head (except light supraantennal tubercles); vestiture light brown.

Head ( Figs 1 , 4 ) subpentagonal, broadest at eyes, HL 0.28 mm, HW 0.30 mm; occipital constriction ( Fig. 4 ; occ) and 'neck' region much narrower than vertex; tempora longer than eyes, moderately strongly convergent caudad and rounded; vertex transverse and convex; frons posteriorly confluent with vertex and convex, anteriorly steeply declining toward mouthparts and flattened; supraantennal tubercles small and weakly raised but distinct. Gular plate ( Fig. 4 ; gp) subtrapezoidal with faint gular sutures ( Fig. 4 ; gs), rapidly narrowing anteriorly and extending onto anterior part of head; posterior tentorial pits ( Fig. 4 ; ptp) small and C-shaped, located in front of transverse impression separating 'neck' region; submentum ( Fig. 4 ; smn) without lateral sutures; hypostomal ridges ( Fig. 4 ; hy) short and strongly convergent posteromesally, not reaching middle between anterior submental margin and tentorial pits; mentum ( Fig. 4 ; mn) subtrapezoidal with rounded sides; prementum ( Fig. 4 ; pmn) long and largely membranous, with indistinctly demarcated ligula bearing pair of setae; labial palps ( Fig. 4 ; lp) long, with particularly elongate palpomere II; each maxilla with subtriangular cardo ( Fig. 4 ; cd), subtriangular basistipes ( Fig. 4 ; bst), elongate but stout mediostipes ( Fig. 4 ; mst), elongate galea ( Fig. 4 ; gal) and lacinia ( Fig. 4 ; lac) each with densely setose mesodistal margin, and long maxillary palp ( Fig. 4 ; mxp) composed of strongly elongate but minute palpomere I, strongly elongate, nearly pipe-shaped palpomere II, strongly enlarged and elongate palpomere IV broadest slightly proximal to middle, and small, subconical palpomere IV. Mandibles ( Fig. 4 ; md) broadly subtriangular, each with robust subapical mesal tooth, basal mesal part not visible in studied specimen. Punctures on vertex and frons fine and inconspicuous; setae moderately dense, long and suberect, setae on tempora and posterior margin of vertex thicker than those on elytra, but not as thick as pronotal bristles. Antennae ( Fig. 1 ) slender, gradually and weakly thickened distally, AnL 0.70 mm; antennomeres I–II elongate, III–V each weakly elongate, VI and VII about as long as broad; VIII–X each distinctly transverse, XI slightly narrower than X, about 1.3× as long as broad, with rounded apex.

Pronotum ( Fig. 1 ) in dorsal view elongate semioval, broadest slightly in front of middle, PL 0.38 mm, PW 0.35 mm; anterior margin weakly rounded, sides strongly rounded, posterior margin weakly bisinuate, anterior pronotal corners weakly marked, posterior corners distinct but obtuse-angled and rounded. Base with median pair of large nearly circular pits separated by narrow and slightly raised area and lateral elongate pits bordered laterally by faint sublateral carinae. Disc covered with fine and inconspicuous punctures and thin, sparse and suberect setae, additionally sides of pronotum and hypomera densely covered with thick bristles. Prosternum with basisternal part ( Fig. 5 ; bst) only slightly shorter than coxal part and sparsely setose; prosternal process ( Fig. 5 ; psp) weakly marked, visible only near anterior margins of procoxae as indistinct and short carina; notosternal sutures ( Fig. 5 ; nss) complete; inner part of each hypomeron demarcated laterally by complete hypomeral ridge ( Fig. 5 ; hyr) and with longitudinal carina extending from its posteromesal margin anteriorly; procoxal sockets ( Fig. 5 ; pcs) narrowly closed; procoxal cavities ( Fig. 5 ; pcc) asetose.

Mesoscutellum not visible between elytral bases, broadly subtriangular, mesoscutoscutellar suture not visible in studied specimen. Mesoventrite with anterior ridge not demarcated; mesoventral intercoxal process ( Fig. 6 ; msvp) carinate and long but moderately elevated, not keel-like, with distinctly marked anterior tip close to anterior margin of mesoventrite and extending up to posterior margins of mesocoxae; mesocoxal projections ( Fig. 6 ; mcp) prominent, without projecting posterior lobes, with mesocoxal sockets ( Fig. 6 ; mscs) located on their mesoventral surface and exposed in ventral view. Prepecti ( Fig. 6 ; pre) long, posterior parts of mesanepisterna and mesepimera not visible in ventral view. Mesoventrite with pair of shallow and indistinctly demarcated asetose impressions behind anterior margin, functioning as procoxal rests ( Fig. 6 ; pcr).

Metaventrite ( Fig. 6 ; v3) subtrapezoidal, broadening posteriorly and with rounded sides, without anterior metaventral process and with metaventral intercoxal process ( Fig. 6 ; mtvp) subtrapezoidal, with long median notch, very narrowly separating metacoxae. Metanepisterna and metepimera narrow.

Elytra ( Fig. 1 ) oval and broadest slightly anterior to middle, EL 0.83 mm, EW 0.60 mm, EI 1.38; humeral calli distinct, developed as short longitudinal protuberances demarcated from inner surface of elytra by distinct subhumeral line; basal impressions short and shallow, each elytron with one small and shallow fovea filled with sparse setae, fovea located closer to mesoscutellum than to humerus; elytral apices separately rounded. Punctures on elytral disc as fine as those on pronotum; setae spare, moderately long, suberect. Hind wings well-developed, about twice as long as elytra.

Legs ( Fig. 1 ) long and slender; procoxae and mesocoxae oval, metacoxae strongly transverse; pro- and mesofemora gradually and weakly clavate, metafemora modified, swollen in basal half and then rapidly narrowing distally, with large shallow pit on posterior (dorsal in Fig. 1 ) surface near middle; tibiae broadening distally and nearly straight; tarsi moderately long, robust.

Aedeagus ( Figs 2–3 , 7–8 ) strongly elongate, AeL 0.35 mm, median lobe symmetrical, oval with subtriangular apical region strongly curved dorsally; endophallus symmetrical and complicated but weakly sclerotized; basal orifice located sub-basally on dorsal wall; parameres long and slender, in lateral view slightly broadening distally, each with two thick and long apical setae.

Female. Similar to male except unmodified metafemora, but their dorsal margin is also slightly concave in the same place as in males; BL 1.48–1.53 mm; HL 0.28–0.30 mm, HW 0.30–0.31 mm, AnL 0.70 mm; PL 0.38 mm, PW 0.35 mm; EL 0.83–0.85 mm, EW 0.58–0.63 mm, EI 1.36–1.43.

Distribution. Central Bolivia.

Remarks. The following characters clearly indicate that Stenichnus andicola is not congeneric with Northern Hemisphere Stenichnus (morphological structures of Stenichnus (s. str.) collaris ( Müller & Kunze, 1822) were illustrated and discussed by Jałoszyński (2013)): submentum lacking lateral sutures (sutures present in Stenichnus ); posterior tentorial pits exposed (hidden in deep transverse groove demarcating 'neck' region in Stenichnus ); eyes distant from occipital constriction and tempora long (eyes very close to occipital constriction and tempora very short); mandibles broad and subtriangular, each with subapical mesal tooth (slender and falciform without subapical tooth in Stenichnus ); pronotum with dense lateral bristles (lacking bristles in Stenichnus ); basisternal part of prosternum only slightly shorter than coxal part (4–5 times shorter in Stenichnus ); hypomeral ridges present and complete (entirely lacking in Stenichnus ); mesoventral intercoxal process strongly elevated, with well-defined anterior tip just behind anterior ridge of mesoventrite and posteriorly extending to posterior margins of mesocoxae (weakly elevated, with anterior tip distant from anterior ridge of mesoventrite and posteriorly extending to about middle of mesocoxae in Stenichnus ); anterior metaventral process absent (present in Stenichnus ); ventrolateral foveae of mesothorax present (lacking in Stenichnus ); mesoventrite behind asetose procoxal rests lacking pair of densely setose impressions (setose impressions present in Stenichnus ); and mesocoxal projections lacking prominent posterior lobes (posterior lobes large and strongly projecting caudad in Stenichnus ). Moreover, Stenichnus has the clypeus with characteristically angulate anterolateral corners (rounded in St. andicola ), slender (and not swollen) maxillary palpomere III, frontoclypeal groove (lacking in St. andicola ), prementum without delimited ligula and lacking a pair of setae (present in St. andicola ), and distinct, deep and asetose basal fovea on each elytron (rudimentary fovea with sparse setae in St. andicola ).

Stenichnus andicola is here assigned to Sciacharis Broun, 1893 on the basis of the head with long tempora (i.e., posterior margins of eyes distant from occipital constriction); clypeus not demarcated from frons by groove; submentum lacking lateral sutures; posterior tentorial pits located clearly in front of transverse impression demarcating the 'neck' region; occipital constriction and 'neck' region much narrower than vertex; prothorax without lateral edges; pronotum with paired antebasal pits and faint sublateral carinae; basisternal part of prosternum only slightly shorter than coxal part; prosternal process weakly developed, with diffused margins and not separating procoxae; notosternal sutures and hypomeral ridges well-developed; procoxal sockets narrowly closed; sides of pronotum with bristles; mesothorax with ventrolateral foveae; mesoventral intercoxal process long and carinate but weakly elevated, not keel-like, posteriorly reaching posterior margins of mesocoxae; metaventral intercoxal process narrow, subtrapezoidal, with median notch, very narrowly separating metacoxae. Moreover, the swollen maxillary palpomere III, pronotum with two pairs of large antebasal pits; mesoventral intercoxal process extending from just behind anterior ridge of mesoventrite to posterior margins of mesocoxae resemble character states known in the subgenus Maorinus Franz, 1980b of Sciacharis .

However, Stenichnus andicola differs from previously studied type species of Sciacharis s. str. and subgenus Maorinus in one rudimentary basal elytral fovea filled with sparse setae, and not two asetose and distinct foveae, as seen in Sciacharis . Also the head in Sciacharis bears thick bristles on tempora and often on the posterior margin of vertex, while the setae present on tempora in St. andicola are thicker than those on elytra, but distinctly thinner than typical bristles densely covering sides of pronotum. These are minor differences and alone cannot be used to establish a new genus or a subgenus of Sciacharis . As mentioned previously ( Jałoszyński 2014a, b), Sciacharis is still very poorly studied genus, showing a great morphological diversity and characters very similar to those of Euconnus Thomson, 1859 . The current subgeneric system of Sciacharis is also unclear and some of its subcomponents (e.g., Magellanoconnus Franz, 1967 or at least some of its species) may in fact belong to separate genera. Certainly St. andicola does not belong in Stenichnus ; and the morphologically closest taxon seems to be Sciacharis (Maorinus) . It is placed here in Sciacharis (incertae sedis), pending further study.

It is noteworthy that Sciacharis is similar to Venezolanoconnus Franz, 1988 , except for clearly different body shape (pear-shaped in Venezolanoconnus , i.e., with strikingly small head, pronotum broadening posteriorly and very broad, stout elytra), large paired antebasal pronotal pits (pits lacking or one pair of rudimentary submedian pits present in Venezolanoconnus ), mandible with subapical mesal tooth (lacking tooth in Venezolanoconnus ), and aedeagus with slender and 'normal' parameres, while that of Venezolanoconnus has strikingly broad parameres nearly surrounding median lobe laterally and expanding onto ventral and dorsal walls, also the endophallus of Sciacharis is symmetrical, while that of Venezolanoconnus is strongly asymmetrical. Relationships between Southern Hemisphere Cyrtoscydmini remain unclear and only a comprehensive phylogenetic analysis, carried out when all genera have been properly revised, may provide robust bases for reclassification of this large and taxonomically challenging group of ant-like stone beetles.

In the original description, Franz (1980a) gives more precise collecting data for the type series of this species: "Gebirgskamm [mountain ridge] westlich (west to) Comarapa, Strasse von [road from] Sta. Cruz nach [to] Cochabamba, Nebelwald [cloud forest] Waldstreu [forest leaf litter], 7.10.1968 ".

Figures

FIGURES 1 – 3. Sciacharis andicola (Franz). Dorsal habitus of male holotype (1), aedeagus in ventral view (2) and enlarged sub-basal region of aedeagus showing details of endophallus (3).

FIGURES 4 – 8. Morphological structures of Sciacharis andicola (Franz), paratype female (4 – 6) and holotype male (7 – 8). Head in ventral view (4); prothorax in ventral view (5); pterothorax in ventral view (6); aedeagus in ventral (7) and lateral (8) views. Abbreviations: ar, anterior ridge; bst, basisternal part of prosternum; cd, cardo; gal, galea; gp, gular plate; gs, gular suture; fo, foramen occipitale; hy, hypostomal ridge; h, hypomeron; hyr, hypomeral ridge; lac, lacinia; lp, labial palp; 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; nss, notosternal suture; occ, occipital constriction; pcc, procoxal cavity; pcr, procoxal rest (= asetose impression); pcs, procoxal socket; pf, profurca; ppf, palpifer; pre, prepectus; psp, prosternal intercoxal process; ptp, posterior tentorial pit; smn, submentum; v 3, metaventrite; vlf, ventrolateral fovea.

FIGURES 28 – 30. Original set of labels of holotypes. Sciacharis andicola (Franz) (28), Meridaphes venezolanus (Franz) (29), and Perumicrus peruanus (Franz) (30).