Delgadobius Chani-Posse & Couturier, 2012

Chani-Posse, Mariana & Couturier, Guy, 2012, Delgadobius amazonensis — a new genus and species of the subtribe Philonthina from Amazonia (Coleoptera: Staphylinidae: Staphylininae), Zootaxa 3568, pp. 81-88 : 82-84

Delgadobius Chani-Posse & Couturier , new genus

( Figs. 1–13 )

Type species. Delgadobius amazonensis Chani-Posse and Couturier , new species.

Diagnosis. The anterolateral margins of pronotum distinctly deflected forming a ridge above the superior marginal line of hypomeron, the hypomeron with an additional line running obliquely between the superior and inferior marginal lines and the tarsi with the third segment apically bilobed and enclosing a rather minute fourth segment, allow prompt recognition among other Philonthina .

Description. Habitus as in Fig. 1 . Length of the body 7.5–7.9 mm. Body elongate, more or less parallel sided, tapering toward sixth visible abdominal segment. Head, thorax, elytra and abdomen from shiny brunneous to piceous-black or black; antennae with first four segments testaceous-brunneous, antennal segments 5 to 11, palpi and legs brunneous to piceous.

Head capsule ( Figs.1, 4 ) rounded with well developed, moderately large eyes; nuchal constriction and nuchal ridge developed laterally and dorsally; infraorbital ridge present, extending to base of mandibles; postgenal and ventral basal ridges well developed; postmandibular ridge and dorsal basal ridge present; epicranium with two pairs of interocular punctures; each side of vertex with three to four postocular punctures forming a triangle or a rhombus; dorsal and ventral surface of head with sparse, fine punctuation and dense, wave-like microsculpture. Antennae inserted nearer to anterior margin of frontoclypeus than to eyes, moderately long, moderately widened toward apex; first four segments bearing only sparse macrosetae, segments 5 to 11 pubescent. Labrum distinctly emarginate and completely sclerotized with numerous and long macrosetae at apical margin. Clypeus entirely fused with frons. Mandible moderately prominent, with setose prostheca well-developed on medial margin; dorsolateral surface grooved ( Fig. 2 ). Maxilla with lacinia elongate and densely setose along entire medial margin, with galea prominent and densely setose at apex ( Fig. 2 ). Maxillary palpus moderately long, segments 1 to 4 glabrous but with sparse setae at apices, segment 1 minute, segment 2 no more than twice as long as maximum width and slightly longer than segment 3, last segment gradually narrowed to subacute apex, longer than preceding segment ( Fig. 2 ). Gular sutures running close to the base of head and not joined before neck ( Fig. 4 ). Mentum transverse, with anterior margin straight to slightly emarginate, and one seta at each latero-apical angle. Ligula small, entire, slightly angulate and sinuate apically. Paraglossae well developed, exceeding ligula in length, each densely setose medially; hypopharynx densely covered by cuticular ciliae. Labial palpus moderately long, segments 1 and 2 with sparse setae, first two segments subequal in length, segment 3 longer than segment 2 and gradually narrowed to subacute apex ( Fig. 2 ).

Pronotum slightly narrowed anteriad; front margin subtruncate, hind margin broadly arcuate, anterior angles subangulate, posterior angles rounded ( Fig. 1 ); hypomeron with an additional line between the superior and inferior marginal lines ( Fig. 5 ); lateral puncture of pronotum bearing long macroseta separated from superior line of pronotal hypomeron by a distance three times as large as diameter of puncture and rather close to the distinct ridge at the anterolateral margin of pronotum ( Fig. 6 ); dorsal surface of pronotum with two rows of punctures subparallel to each other, with two sublateral groups of punctures, each with 4–5 punctures; surface with fine and dense microsculpture of transverse and oblique waves. Prosternum short, triangular, with only a medial prominence, not carinate, not longitudinal along basisternum, basisternum longer than furcasternum, with two medio-apical macrosetae ( Fig. 5 ). Mesoscutellum with two transverse carinae ( Fig. 3 ). Mesoventrite short, with sternopleural suture nearly transverse and sternacostal carina convex posteriad, laterally directed towards sternopleural suture and reaching it; mesoventral intercoxal process subtruncate. Metaventrite in front of hind coxa arcuately emarginate on each side; metaventral process short, split apically. Legs moderately long; front tibia with setae only, mid and hind tibiae spinose on lateral face, with ventral setae denser on front tibia than on mid and hind tibiae; dorsal surface of all tarsal segments glabrous except for scattered, long marginal setae, and pair of setae at apex of last segment about half as long as claws; front tarsus in both sexes with first four segments slightly dilated, ventral surface of segments 1 to 4 with dense, long whitish adhesive setae ( Fig. 7 ); tarsal segment 3 of all tarsi distinctly bilobed apically and with long whitish adhesive setae ventrally, tarsal segment 4 rather small and enclosed by preceding segment ( Figs. 7, 8 ).

Elytra with sub-basal ridge short, immediately adjacent to elytral articulation; punctation moderately coarse, transverse distance between punctures distinctly more than diameter of one puncture. Hind wings with veins CuA and MP4 fused in one vein, MP3 present.

Abdomen with paired prototergal glands on tergum 1 manifested by invaginated capsules with small openings ( Fig. 3 ); terga 3 to 5 with anterior and posterior transverse basal carinae; tergum 7 (fifth visible) with whitish apical seam of microtrichae; surface with fine and dense microsculpture of transverse and oblique waves; hind margin of tergum 8 (sixth visible) subtruncate in both sexes.

Male genitalia. Sterna 7 and 8 emarginate medio-apically, emargination with semi-membranous extension. Genital segment with styli of tergum 9 stout and moderately setose apically; tergum 10 subangulate at apex ( Fig. 9 ); sternum 9 with proximal portion long, asymmetrical ( Fig. 10 ). Aedeagus with parameres fused to one short sclerite only attached to median lobe at base; median lobe elongate, with apical part distinctly narrowed ( Figs. 11, 12 ).

Female genitalia. Sterna 7 and 8 straight to slightly sinuate apically. Ovipositor consisting of paired proximal and distal gonocoxites, the latter bearing styli with two apical setae ( Fig. 13 ).

Etymology. The genus name is dedicated to Dr. César Delgado, entomologist and friend of the second author, in recognition of his long research activity in the locality where this genus was found (Iquitos).

Distribution and diversity. Delgadobius is a Neotropical genus with only one species known at present, recorded from Iquitos ( Peru) and Manaus ( Brazil), which are included in the Amazonian subregion ( Morrone, 2009).

Taxonomic notes and relationships. With exception of the condition shown by the infraorbital ridge in Delgadobius which is well-developed and extends far beyond the postgenal ridge, all other characters meet those that define Philonthina according to Smetana and Davies (2000): maxillary and labial palpus each no more than moderately slender and long; neck with dorsal basal ridge; middle portion of disc of neck virtually impunctate; ligula entire; pronotal hypomeron no more than moderately inflexed below anterior angle of pronotum, meeting prosternum at a very flat angle, with both sclerites fused, and notosternal suture absent; superior marginal line of pronotal hypomeron deflexed under anterior angle of pronotum before continuing onto anterior margin of pronotum; tarsal formula 5, 5, 5; empodial setae between claws of all tarsi absent. Smetana and Davies (2000) describe the infraorbital ridge as “usually rudimentary” in Philonthina , “extending at most very little in front of postgenal ridge”. Although Delgadobius does not share this condition with most members of Philonthina , exceptions for this character are also observed in Philonthoblerius Tottenham 1949 , Endeius ovaliceps Coiffait 1981 and Flohria Sharp 1884 .

Current available keys to genera of Philonthina are mostly based on the Holarctic fauna ( Smetana 1995, Smetana and Davies 2000, Newton et. al. 2000, Navarrete-Heredia et al. 2002) and they do not reflect the diversity present in other zoogeographical regions. This is the case for this new genus, which does not fit into any of those keys.

An assessment of the phylogenetic affinities of Delgadobius with the other Neotropical genera of the subtribe and representatives from other regions (Chani-Posse, in press) supports the statement that Delgadobius is probably endemic to the Neotropical Region. According to this assessment, the genera Atopocentrum Bernhauer , Chroaptomus Sharp and the new genus may constitute a derived lineage within the group of Neotropical Philonthina . Although each of these three genera is characterized by striking morphological features (e.g. Chani- Posse, 2006 for Chroaptomus ), they share the following characters: lateral puncture of pronotum with long seta at a distance about three times as large as diameter of puncture; prosternum without mid-longitudinal carina; sternopleural (anapleural) suture transverse or nearly transverse; mesoventrite with medial carina in coxal acetabulum and intercoxal process rounded. On the other hand, the presence of an additional oblique line connecting the superior and inferior lines of the pronotal hypomeron in Delgadobius is at present only found in Craspedomerus Bernhauer within Philonthina and in Holisus Erichson (Hyptiomina) .

A more complete understanding of the phylogenetic affinities of Delgadobius will require further studies on a broader scale that include both pantropical elements of Philonthina and a thorough evaluation of the current classification at a supra-generic level.

Figures

FIGURES 1 – 13. Delgadobius amazonensis: 1, habitus; 2, mouthparts; 3, mesonotum, metanotum and first abdominal segments; 4, head, ventral view (IoR = infraorbital ridge); 5, prosternum and hypomeron (aL = additional line, Pr = pronotal ridge); 6, pronotum and hypomeron, lateral view; 7, front tarsus, ventral view (S = segment); 8, mid tarsus, lateroventral view; 9, tergum 10 (male); 10, sternum 9; 111, aedeagus, dorsal view; 12, aedeagus, lateral view; 13, gonocoxites of female genital segment. Scale bars = 0.4 mm.