Scaphidium spinipenne, Löbl, 2023

Löbl, Ivan, 2023, Three new species of Scaphidiinae from Mindanao and Palawan (Coleoptera: Staphylinidae), Journal of Tropical Coleopterology 4, No. 2, pp. 1-10 : 2-6

Scaphidium spinipenne sp. nov.

urn:lsid:zoobank.org:act:FB667474-A894-46B6-BE0A-852F0F8C7592

( Figures 1-5 )

Type material. Holotype male: Phil.: Mindanao Sibagat Agusan del Sur , VII.2019 [001 M] ( MHNG).

Description. Total length 4.10 mm, body length without head and abdomen 3.40 mm. Head, antennomeres I and VI, nearly entire pronotum, most of elytra and legs light ochraceous; antennomere VII darkened (following antennomeres missing). Narrow basal margin of pronotum darkened. Elytron blackish on narrow basal humeral stripe; middle of elytral disc with two blackish spots, inner spot with irregular anterior and posterior margins situated between first and third discal striae, outer spot touching fourth discal stria situated at same level; epipleuron dark brown. Upper part of hypomeron ochraceous, inferior part of hypomeron darkened. Ventral side of thorax and abdomen ochraceous. Legs ochraceous, with trochanters and bases of femora darkened. Head with eyes about 1 mm wide, frons very finely punctate, at narrowest point 0.18 mm wide; eyes prominent. Pronotum about 1.40 mm long, at anterior margin 0.90 mm wide, at base about 2.10 mm wide; pronotal disc convex in middle and very finely punctate, with punctures indistinct at magnification 100 times; lateral margins sinuate, convexly expanded in basal third, slightly concave in anterior two thirds; lateral margin carinae exposed in dorsal view; lateral margin stria sparsely punctate; anterior margin bead in middle twice as large as on sides, anterior margin stria impunctate; antebasal puncture row impressed, dense, not interrupted in middle, consisting of coarse, evenly large punctures; discal punctation very fine, as that on frons. Exposed part of scutellum nearly twice as wide as long. Elytra flat, inflexed, strongly narrowing apicad, elytral disc below level of pronotal centre; lateral margins rounded in basal third, oblique in middle third, lateral margin carinae exposed in dorsal view, lateral margin striae punctate; sutural striae not extending along basal margin, coarsely and densely punctate; adsutural areas sightly convex, with hardly visible punctation at magnification 100 times. Elytral disc with five impressed, longitudinal rows of coarse puncture; first row starting about 0.20 mm posterior of level of scutellar tip and extending up to apical fourth of sutural length; second row starting near basal margin of elytron and as first row extending apically up to apical fourth of sutural length; third and fourth rows starting as the second row near base but longer, ending about 0.25 mm anterior of apical margin of elytron; fifth row starting as second to fourth rows near base, longer than fourth row, ending about 0.10 mm anterior of apical margin of elytron; row intervals somewhat convex, very finely punctate, several coarse punctures scattered near apical margins. Mesoventral ridge raised between procoxal cavities. Mesoventrite and mesanepisternum impunctate, latter with strigulate microsculpture. Pseudepimeron extending to mesocoxa, narrow. Metaventrite with entire discrimen, lacking premetacoxal lines, with few fine punctures near mesocoxal cavities, metaventral sides with strigulate microsculpture, impunctate on prevailing surface; lateral margin impressed along metanepisternum; submesoxocal lines punctate. Metanepisternum distinctly narrowed anteriad. Legs elongate and slender. Abdomen impunctate, with strigulate microsculpture.

Male. Elytron with spine at middle of apical margin, latter rounded outward, oblique between spine and sutural angle ( Fig. 1 ). Entire mesal area of metaventrite punctate and pubescent, with long horizontal setae, longest setae extending to apical margin of ventrite I. Femora lacking particular sexual characters. Protibia in basal half straight, in apical half weakly curved, gradually thickened apicad, at apex about twice as wide as at base. Protarsomeres I to III weakly enlarged, with short ventral setae. Mesotibia 1.5 times as long as protibia, as protibia weakly curved and gradually widened apicad, at apex twice as wide as at base, with sort setae. Mesotarsi long, mesotarsomeres I to III strongly widened, with long ventral setae, lacking tenent setae. Aedeagus as Figs 2-5 , 1.08 mm long, apicomesal parts of parameres membranous. Female. Unknown.

Etymology. The species epithet is a Latin adjective referring to the spinose elytron.

Diagnosis. The new species has large eyes, the head width exceeding the width of the anterior margin of pronotum, the pronotum convex dorsally, the elytra flattened with five coarsely punctate striae, and long legs as Scaphidium striatipenne Gestro, 1879 , Scaphidium sulcipenne Gestro, 1879 and Scaphidium tricolor Achard, 1920 from the Great Sunda Islands. The shape of the elytral apices bearing a spine is unique for S. spinipenne . In addition, this species is distinguished from S. striatipenne and S. sulcipenne by the unicolor pronotum and the light apices of elytra. Unlike S. spinipenne , males S. sulcipenne have protibiae widened at apices and protarsi and mesotibiae with conspicuously long setae, while the males S. striatipenne have a profemoral tubercle. Scaphidium tricolor may be also distinguished by its male profemora that are denticulate ventrally and protibiae rugose in apical halves.

Comments. Achard (1922a) established the genus Hemiscaphium to accommodate species of Scaphidium Olivier, 1790 having particularly large eyes, a prosternum not or weakly carinate, a mesoventrite with a robust carina, a convex pronotum, long and slender legs, often bearing conspicuous sexual characters, and elytra strongly narrowed apicad and bearing two to five longitudinal punctate striae. Achard (1922b) provided a synopsis of the 12 species assigned to Hemiscaphium , all but the Myanmar Hemiscaphium brunneopictum Achard, 1922 reported from the Sundaland islands. A character analysis ( Leschen & Löbl, 1995) showed that Hemiscaphium and several other Scaphidiini genera established by Achard (1922a) were based upon variable characters and without well-defined synapomorphies or autapomorphies, resulting in their placement in synonymy of Scaphidium .

The antennae of the sole available specimens of S. spinipenne have been broken off, four club segments of one antenna are missing and only two basal antennomeres of the second antenna are present. Nevertheless, the species exhibits unique and conspicuous characteristics that in my opinion justify its description. To date, 12 species of Scaphidium have been reported from the Philippines. Only one of them, Scaphidium seriatum Heller, 1917 , has elytral disc with longitudinal rows of coarse punctures. The latter species differs notably from Scaphidium spinipenne by the elytra having only two puncture rows, and the smaller and uniformly rufous body ( Heller, 1917). Members of Scaphidium are uncommon in the collections I had occasion to examine, possibly because they are night-active ( Tang et al., 2014).

Figures

Figure 1. Dorsal habitus of Scaphidium spinipenne sp. nov.

Figures 2-7. Male genitalia. 2-5. Scaphidium spinipenne sp. nov.; 2. Aedeagus in dorsal view, scale =0.2 mm; 3. Aedeagus in lateral view, without basal bulb, scale = 0.1 mm; 4. Paramere in ventral view, scale = 0.1 mm; 5. Internal sac, scale = 0.1 mm; 6, 7. Baeocera alamada sp. nov., aedeagus in dorsal and lateral views, scale = 0.2 mm.