Scydmaenilla King
Creators: name: Jałoszyński, Paweł
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Scydmaenilla

description: Genus Scydmaenilla King, stat. rest.
Scydmaenilla King, 1864: 93. Type species: Scydmaenilla pusilla King, 1864 (monotypy). Reduced to subgenus of Stenichnus by Franz (1975).
Revised diagnosis. Eyes located posteriorly; occipital constriction nearly as broad as vertex; fronto-clypeal groove absent; mandibles subtriangular, with abruptly demarcated broad basal part and subapical tooth on mesal margin; submentum trapezoidal, completely demarcated from hypostomae by lateral sutures; hypostomae elongate and demarcated from genae by complete hypostomal ridges; posterior tentorial pits hidden in deep groove between submentum and gular plate; antennae with 3-segmented club; pronotum with one pair of lateral ante-basal pits connected by transverse groove, with variously distinct lateral marginal carinae visible in posterior half; prosternum with moderately narrow basisternal part demarcated from procoxal cavities by carina, at each side with shallow lateral impression, procoxal cavities separated in middle by fine carina; hypomera not demarcated from pronotum; mesoventrite with asetose impressions separated in middle, with or without lateral setose impressions; mesoventral intercoxal process moderately narrow and moderately projecting ventrally, with distinct posterior tip separated from metaventrite; mesocoxal projections with or without posterior lobes; metaventrite with metaventral anterior process, with short and broad metaventral intercoxal process bearing median notch; aedeagus with free parameres.
Redescription. Body (Figs. 74–75, 84–85, 93–98) from flattened to strongly convex, slender, with long appendages, cuticle glossy, distinctly setose.
Head (Figs. 79, 86, 90, 93–98, 99–104) subtriangular, broadest at posteriorly located eyes; neck region short and subcylindrical, only slightly broadened in middle; occipital constriction (Figs. 79, 90; occ) in the narrowest place nearly as wide as vertex; tempora (Figs. 79, 90; tm) much shorter than eyes; vertex and frons (Fig. 86; vt, fr) between eyes confluent and convex, fronto-clypeal groove absent.
Labrum (Fig. 86; lb) transverse with rounded sides and anterior margin.
Mandibles (Figs. 86, 90; md) symmetrical, each with broad basal part and moderately slender distal part, mesal margin with median tooth.
Each maxilla with elongate galea and lacinia (Figs. 79, 90; gal, lac) and long maxillary palp (Fig. 79; mxp) composed of minute palpomere I, strongly elongate and broadening distally palpomere II, long and pedunculate palpomere III only slightly narrowing from middle towards apex, and slender, elongate subconical, pointed palpomere IV.
Labium with trapezoidal submentum (Figs. 79, 90; smn) posteriorly demarcated from gular plate (Figs. 79, 90; gp) by deep transverse groove in which posterior tentorial pits are hidden, laterally demarcated from hypostomae (Figs. 79, 90; h) by complete lateral sutures (Figs. 79, 90; lss); subtrapezoidal mentum (Figs. 79, 90; mn); and elongate prementum (Figs. 79, 90; pmn) with broadly separated, long 3-segmented labial palps (Figs. 79, 90; lp). Laterally mouthparts are demarcated from genae by complete hypostomal ridges (Figs. 79, 90; hr).
Gular plate (Figs. 79, 90; gp) large and subtriangular in shape, with distinct gular sutures (Figs. 79, 90; gs).
Antennae (Figs. 74–75, 84–85, 93–98) with club composed of 3 antennomeres, in some species antennomere X asymmetrical.
Prothorax (Figs. 74–75, 78, 80, 84–85, 89, 91, 93–98, 99–104) in dorsal view with rounded anterior and lateral margins of pronotum, at base with transverse groove connecting one pair of lateral ante-basal foveae or impressions, with lateral marginal carinae or edges in posterior third of pronotum (in some species indistinct or barely marked; see Remarks); hypomera (Figs. 80, 91; hy) not demarcated from notum. Prosternum (Figs. 80, 91) with moderately long basisternal part (Figs. 80, 91; bs) separated from procoxal cavities (Figs. 80, 91; pcc) by carina, laterally basisternal part of prosternum with shallow impression (Figs. 80, 91; lpi) filled with setae different (i.e., denser or in some species shorter) than those on remaining parts of sternum or with fine microsculpture; procoxal cavities (Figs. 80, 91; pcc) separated in middle by fine prosternal intercoxal carina; procoxal sockets (Figs. 80, 91; pcs) closed by lateral expansion of sternum; notosternal sutures (Figs. 80, 91; nss) complete.
Mesoventrite (Figs. 78, 81, 87, 89, 92, 99–104) with narrow anterior ridge (Figs. 81, 92; ar), lateral asetose impressions separated in middle (Figs. 81, 92; ai), without (Figs. 81, 92, 99–103) or with (Fig. 104; si) lateral setose impressions moderately narrowly separated in middle and broadly separated from mesocoxal cavities; mesocoxal projection (Figs. 81, 92; mcp) without carina and without (Figs. 81, 92, 99–103) or with (Fig. 104; pl) posterior lobe bearing dense setae along posterior margin; mesoventral intercoxal process (Figs. 81, 87, 92; msvp) moderately narrow, with distinct posterior tip separated from metaventrite.
Metaventrite (Figs. 78, 81, 87, 89, 92, 99–104) broader than long, with metaventral anterior process (Figs. 81, 87, 92; mtap); metaventral intercoxal process (Figs. 81, 92; mtvp) broad and short, with distinct median notch. In two species, metaventrite with lateral carinae (Figs. 103–104; lmtc) extending from posterior margin of mesocoxal projection to slightly more than half length of ventrite.
Elytra (Figs. 74–75, 84–85, 93–98) oval, with well-marked humeral calli; each elytron with one or two rudimentary basal foveae barely noticeable in dry-mounted specimens. Hind wings well-developed.
Legs (Figs. 74–75, 84–85, 93–98) long and slender; femora clavate, tibiae nearly straight, in some species metatibiae with sub-apical group of long setae forming slender brush (Figs. 93, 95–96), tarsi strongly elongate.
Abdominal sternites VII and VIII separated by indistinct suture (Figs. 78, 81).
Aedeagus (Figs. 82–83, 111–112, 114–115) variable in shape, from strongly elongate to stout, with symmetrical or nearly symmetrical internal armature; parameres free, with apical and subapical setae.
Spermatheca (Figs. 81, 103) relatively large, globular, thick-walled, with slender and long ductus spermathecae.
Distribution and composition. Seven named and one undetermined species are distributed in eastern and south-eastern Australia (three in Queensland, three in New South Wales and one in South Australia) and southeastern Tasmania (one species).
Remarks. Franz (1975) redescribed Scydmaenilla and its type species, S. pusilla on the basis of a non-type female (Figs. 84–92) preserved in NHM and identified by Lea. However, this specimen belongs to a clearly different species than two syntypes from the collection of King (AMS), not examined by Franz. The genus was correctly identified by Lea, and this specimen (in addition to the syntypes of S. pusilla) was used to describe some details of morphology of Scydmaenilla s. str. given above.
Within Australo-Pacific region, Scydmaenilla, and especially the new subgenus described below and represented by S. adelaidensis, is most similar to Stenichnus. Most details of the head structure, prosternum, meso- and metaventrites of Scydmaenilla highly resemble those known in Stenichnus s. str., and the mesoventrite in S. adelaidensis differs from that of Stenichnus s. str. only in the prepecti not demarcated from anterior parts of mesocoxal projections (Fig. 104) (completely demarcated in Stenichnus, Fig. 23). The lack of fronto-clypeal groove (present in Stenichnus); subtriangular mandibles with the mesal teeth (falciform and without mesal teeth in Stenichnus); one pair of lateral foveae or impressions and a transverse groove on pronotal base (at least four foveae or large punctures in Stenichnus); lack of one deep elytral basal fovea (present in Stenichnus) and a different structure of the aedeagus and spermatheca justify the position of Scydmaenilla as a separate genus, and not merely a subgenus of Stenichnus. The major key characters are compared in Table 1.
Although it was not possible to examine details of the prementum in the fragile specimens available for the study, the long and flexible prementum and broadly separated bases of maxillary palps suggest that the prementum may be modified in a similar way as that in Stenichnus. Additional specimens are necessary to clarify this morphological question.
In the type species of the genus, S. pusilla, the pronotum has distinct lateral marginal carinae or edges in posterior third, such carinae can also be found in the undetermined female of Scydmaenilla from NHM and in S. sydneyana and S. adelaidensis, while in the remaining four species carinae are indistinct or barely discernible. The presence or absence of the lateral edges or marginal carinae of pronotum was often used as an important diagnostic character to define genera in Cyrtoscydmini. However, in Scydmaenilla the variability in the lateral margins of pronotum does not seem to correlate with any other characters. Scydmaenilla pusilla (with distinct edges) differs from S. constricta, S. queenslandica, S. thompsoniana and S. brisbanensis (all species with indistinct edges) only in minor characters and not in any structures potentially useful for defining separate genera. Only S. adelaidensis (a species with distinct lateral pronotal edges) differs from S. pusilla (and all other congeners) in the structure of the mesoventrite and elytral base; these differences justify a placement of this species in a separate subgenus.
Scydmaenilla was placed in Scydmaenini by Csiki (1919). However, this genus was correctly treated as belonging to Cyrtoscydmini by Franz (1975) and Newton & Franz (1998).
description: Published as part of Jałoszyński, Paweł, 2013, Revision of subgenera of Stenichnus Thomson, with review of Australo-Pacific species (Coleoptera, Staphylinidae, Scydmaeninae), pp. 39-79 in Zootaxa 3630 (1) on pages 63-69, DOI: 10.11646/zootaxa.3630.1.2, http://zenodo.org/record/283467