Phaenocephalus Wollaston, 1873

Gimmel, Matthew L., 2013, <strong> Genus-level revision of the family Phalacridae (Coleoptera: Cucujoidea) </ strong>, Zootaxa 3605 (1), pp. 1-147 : 18-23

1. Phaenocephalus Wollaston, 1873

( Figs. 2i, j ; 4 ; 37a, b )

Phaenocephalus Wollaston 1873: 167 . Type species: Phaenocephalus castaneus Wollaston 1873 , fixed by monotypy. Phalacratomus Scott 1922: 240 . Type species: Phalacratomus exiguus Scott 1922 , fixed by original designation. Syn. nov. Heterostilbus Champion 1924 b: 165 . Type species: Heterostilbus marginatus Champion 1924 , fixed by original designation.

Syn. nov.

Type material. Phaenocephalus castaneus Wollaston : one syntype, only a single maxilla and labium remain (on an acetate card in Canada balsam, “ Phanocephalus [sic] [black line dividing label] \ Maxilla, Labium of \ Aug 1885 [handwritten] // 759 // Matthews coll. \ 1904–120. [on underside of label]” ( BMNH). The lectotype is not designated with the expectation that additional, intact specimens (Wollaston implied that there were multiples) will turn up from the syntype series.

Phalacratomus exiguus Scott : 10 syntypes found in BMNH, card mounted (plus one missing from card), the first specimen (with Scott’s handwritten “ TYPE ” label) is chosen as the lectotype in order to stabilize the name, “19 [handwritten on card] // Type [red-bordered disc] // Silhouette, 1908 \ Seychelles Exp. // Seychelle Islands. Percy Sladen Trust Expedition. 1913–170. [on underside of label] // Phalacratomus exiguus \ TYPE. H. Scott [handwritten] // LECTOTYPE \ Phalacratomus \ exiguus Scott \ des. M.L. Gimmel 2011 [red label]” ( BMNH). Nine syntypes from other localities in the Seychelles (including Mahé) were examined, each with label affixed “ PARALECTOTYPE \ Phalacratomus \ exiguus Scott \ det. M.L. Gimmel 2011 [yellow label]”.

Heterostilbus marginatus Champion : five syntypes in BMNH, first one (with Champion’s “type” label) selected as the lectotype to stabilize the species name, “W. Almora Divn \ Kumaon U.P. \ June 1917. HGC. // 996 [handwritten] // Type H. T. [red-bordered disc] // Heterostilbus marginatus type Ch [handwritten] // Heterostilbus (n. gen.) marginatus, Ch. // Ent. Mo. Mag. 1924. \ G. C. C. det. [on underside of label] // G.C. Champion. \ Brit. Mus. \ 1924–63. [on underside of label] // LECTOTYPE \ Heterostilbus \ marginatus Champion \ des. M.L. Gimmel 2011 [red label]” ( BMNH), card mounted. Four syntypes with labels reading “W. Almora” or “Bhatkot” were identified as paralectotypes, while two specimens with “Ranikhet” were excluded from the syntype series (only five specimens and the two former localities were listed in the original description). Each of the four received the label “ PARALECTOTYPE \ Heterostilbus \ marginatus Champion \ det. M.L. Gimmel 2011 [yellow label]”.

Diagnosis. May be readily recognized by the complete or almost complete lack of a sutural stria, elevated mesoventral disc, short tarsi with formula 4-4-4, and ovoid antennomere I.

Description. Very small to small, total length 1.1–1.8 mm. Dorsal surface from completely testaceous to completely black, often with lighter pronotum and elytral margins ( Fig. 37a, b ). Tibial spur formula 0-1-1, tarsal formula 4-4- 4 in both sexes.

Head. Distinctly constricted behind eyes ( Fig. 2j ); without median endocarina. Eyes medium-sized; facets flat; interfacetal setae absent; not emarginate medially; without posterior emargination; periocular groove absent; without setose groove ventrally behind eye. Frontoclypeus emarginate above antennal insertion; clypeal apex arcuate-truncate. Antennomere I ovoid; antennal club loosely 3-segmented, club symmetrical, nearly cylindrical, long, sometimes longer than remainder of antenna; antennomere XI not turbinate ( Fig. 4b ). Mandible ( Fig. 4a ) stout, with apex bidentate; without retinaculum; mandible without ventral ridge. Maxillary palpomere IV fusiform, inner edge slightly swollen medially; galea rounded; lacinia setose, without spines. Mentum with sides divergent toward apex; labial palpomere III constricted at apex ( Fig. 2i ). Labrum with apical margin arcuate. Gular sutures long, extending more than halfway to ventral mouthparts.

Thorax. Pronotum without obvious microsetae; with distinct scutellar lobe. Prosternum anteriorly with discontinuous row of marginal setae, a gap present medially, setae normal; procoxal cavity with anterolateral notchlike extension; prosternal process rounded in lateral view, not setose preapically, without spinelike setae at apex. Procoxae nearly contiguous; protrochanter without setae; protibia without ctenidium on kickface, apical spurs absent ( Fig. 4c ). Scutellar shield small, width at base less than length of eye. Elytron without spectral iridescence; sutural and discal striae completely absent; without transverse strigae; lateral margin without row of sawtooth-like setae. Mesoventral plate deeply notched anteriorly, not extending posteriorly to metaventrite, not forming procoxal rests; mesoventral disc elevated medially, forming a large plate anterior to metaventral process, not setose; mesanepisternum with complete transverse carina; mesocoxae separated by more than half width of a coxal cavity ( Fig. 4f ). Mesotarsomere III not bilobed. Metaventral process extending anteriorly just to halfway point of mesocoxae; metaventral postcoxal lines not separated from mesocoxal cavity margin ( Fig. 4f ); discrimen long, extending more than halfway to anterior margin of metaventral process; metendosternite with anterior tendons widely separated, ventral process intersecting ventral longitudinal flange at anterior margin ( Fig. 4g ). Anterior margin of metacoxa without emargination sublaterally; metacoxal plate without transverse line; metatibial foreface with apical ctenidium straight, perpendicular overall to long axis of tibia; apical spur cylindrical, distinctly shorter than width of tibial apex; metatarsomeres compacted, nearly identical to mesotarsomeres, joint between I and II flexible ( Fig. 4d ); metatarsomere III not bilobed. Hind wing ( Fig. 4e ) with distinct, straplike anal lobe; leading edge with incomplete row of long setae; AA 3+4 not apparent; cubitoanal system not forked; CuA 2 and MP 3+4 without distal remnants; r4 absent; apical field large, occupying well over half of wing, with large curved fleck and two smaller flecks present distal to rp-mp2; small transverse sclerite and small oval sclerite present just distal to end of radial bar.

Abdomen. Abdominal ventrite I without paired lines or calli; spiracles absent on segment VII. Male with aedeagus upright in repose; tegmen ( Fig. 4h ) with symmetrical anterior margin, parameres hinged to basal piece, parameres with medial longitudinal division; penis ( Fig. 4i ) parallel-sided, with fields of endophallic spicules, bilobed or complex apically; spiculum gastrale Y-shaped, with long basal rod. Female ovipositor weakly sclerotized, palpiform.

Immature stages. Unknown.

Bionomics. Specimens have been collected using diverse methods, including forest litter sifting (unusual for the family), Malaise traps, canopy fogging, pitfalls, and beating banana leaves.

Distribution and diversity. I have seen specimens from Africa as far west as Nigeria, Cameroon, and Angola, to Madagascar and the Seychelles (first records for the Afrotropical Region), eastward through the Indian Subcontinent to Japan and southeast Asia (including the Philippines), and into the Australian Region (first records for this region) from New Guinea and Australia (Northern Territory, Queensland, Western Australia, and Lord Howe Island). I have also seen specimens from Fiji (NZAC), where it appears to be the only phalacrid. Many species are undescribed.

Included species (8):

Phaenocephalus castaneus Wollaston, 1873 (Distribution: Japan) (type!) Phaenocephalus coomani Paulian, 1950 (Distribution: Vietnam) (type!) Phaenocephalus exiguus ( Scott, 1922) , comb. nov. ( Phalacratomus ) (Distribution: Seychelles) (type!) Phaenocephalus kobensis (Champion, 1925) , comb. nov. ( Heterostilbus ) (Distribution: Japan, Taiwan) (type!) Phaenocephalus laevigatus (Champion, 1924) , comb. nov. ( Heterostilbus ) (Distribution: India) (type!) Phaenocephalus longiclava (Champion, 1925) , comb. nov. ( Heterostilbus ) (Distribution: Malaysia,

Philippines) (type!) Phaenocephalus marginatus (Champion, 1924) , comb. nov. ( Heterostilbus ) (Distribution: India) (type!) Phaenocephalus minutulus (Champion, 1924) , comb. nov. ( Heterostilbus ) (Distribution: Malaysia, Sri Lanka)

(type!)

Discussion. This genus was first described as a member of the Corylophidae ( Wollaston 1873) , albeit with reservations. Matthews (1899) formally recognized its distinctness by erecting the monotypic family Phaenocephalidae . An additional species was added by Paulian (1950), but its family placement remained unchanged until Pakaluk (1991), who transferred it to Phalacridae based on a detailed examination of a range of anatomical features. My examination and analyses confirm that Phaenocephalus fits within the diagnosis of Phalacridae presented above.

Scott’s genus Phalacratomus falls well within the concept of Phaenocephalus outlined in the diagnosis above, as does the Champion genus Heterostilbus , and I am newly proposing them as junior synonyms of Phaenocephalus .

Figures

FIGURE 2. Key characters for Phalacridae. (a) Schematic of dorsal characters showing small scutellar shield and two sutural striae. (b) Schematic of dorsal characters showing large scutellar shield and one sutural stria. Frontal view of head capsule of (c) Stilbus; (d) Phalacrus; (e) Tolyphus. (f) Maxillary palpus of Megistopalpus. Labial palpus of (g) Grouvelleus; (h) Phalacrinus (scale bar = 0.5 mm); (i) Phaenocephalus (scale bar = 0.2 mm). Dorsal view of head capsule of (j) Phaenocephalus; (k) Phalacrinus; (l) Acylomus (scale bars = 0.5 mm). Ventral view of head capsule of (m) Xanthocomus; (n) Nesiotus.

FIGURE 4. Phaenocephalus sp., male. (a) Left mandible, dorsal; (b) left antenna (scale bar = 0.5 mm). (c) Left protibia and tarsus, dorsal; (d) left metatibia and tarsus, ventral (scale bar = 0.5 mm). (e) Hind wing (scale bar = 1.0 mm). (f) Meso- and metaventrite, ventral (scale bar = 0.5 mm). (g) Metendosternite (scale bar = 0.5 mm). (h) Tegmen, ventral; (i) penis, ventral (scale bar = 0.5 mm).

FIGURE 37. Photographs. Phaenocephalus sp.: (a) dorsal; (b) ventral. Phalacrinus sp.: (c) dorsal. Ranomafanacrinus nigrinus, holotype: (d) dorsal; (e) lateral; (f) ventral. Acylomus aciculatus: (g) dorsal; (h) ventral. Acylomus bicolor: (i) dorsal.