Nesiotus Guillebeau, 1896

Gimmel, Matthew L., 2013, <strong> Genus-level revision of the family Phalacridae (Coleoptera: Cucujoidea) </ strong>, Zootaxa 3605 (1), pp. 1-147 : 36-38

5. Nesiotus Guillebeau, 1896

( Figs. 2n ; 9 ; 38a )

Nesiotus Guillebeau 1896: 298 . Type species: Nesiotus olibroides Guillebeau 1896 , fixed by monotypy.

Type material. Nesiotus olibroides Guillebeau : one specimen located in MNHN, male, card-mounted, genitalia dissected, here designated as a lectotype to stabilize the species and generic names, “Alluaud [handwritten] // Diego Suarez [handwritten] // MUSEUM PARIS \ COLL. GÉNÉRALE // HOLOTYPE [red label] // Nesiotus \ olibroides \ Guilb. [handwritten] // LECTOTYPE \ Nesiotus \ olibroides Guillebeau \ des. M.L. Gimmel 2009 [red label]” ( MNHN). Although Guillebeau mentions “deux examples” in the original description, only one specimen was discovered in MNHN. The paralectotype may be located in BMNH ( Scott 1922: 236).

Diagnosis. May be recognized by the divergent, smoothly arcuate metaventral postcoxal lines, single elytral sutural stria, rows of microsetae on the elytra, metatarsomere I shorter than II with joint between them rigid, prosternal process angulate when viewed laterally and with pair of stiff setae at apex, ventral lobe of the eye expanded posteriorly, mandible without a ventral ridge, and the tegmen with parameres fused to basal piece.

Description. Very small to small, total length 1.2–2.0 mm. Dorsal color reddish-testaceous to piceous, darker specimens often with reddish patches basally on elytra ( Fig. 38a ). Tibial spur formula 2-2-2, tarsal formula 5-5- 5 in females, 5-5- 4 in males.

Head. Not constricted behind eyes. Eyes medium-sized, with ventral lobe expanded posteriorly ( Fig. 2n ); facets slightly convex; interfacetal setae absent; distinctly emarginate medially; with sharp posterior emargination; periocular groove absent; with transverse setose groove ventrally behind eye ( Fig. 2n ). Frontoclypeus emarginate above antennal insertion; clypeal apex arcuate-truncate. Antennal club 3-segmented, club weakly asymmetrical, as long as or longer than remainder of antenna (most extreme in male, Fig. 9b ), antennomere XI not constricted. Mandible ( Fig. 9a ) with apex bidentate; without retinaculum; mandible without ventral ridge. Maxillary palpomere IV fusiform, inner edge swollen medially; galea short, rounded; lacinia with two stout spines. Mentum with sides divergent toward apex; labial palpomere III fusiform. Labrum with apical margin arcuate. Gular sutures long .

Thorax. Pronotum with distinct microsetae; with moderately well-developed scutellar lobe. Prosternum anteriorly with marginal setae distributed in two patches, setae normal; procoxal cavity with anterolateral notchlike extension; prosternal process angulate in lateral view, not conspicuously setose preapically, with pair of spinelike setae at apical corners. Protrochanter without setae; protibia without ctenidium on kickface ( Fig. 9c ). Scutellar shield small. Elytron with weak to moderate spectral iridescence; one sutural stria present; discal striae not impressed and apparently impunctate, but represented by rows of microsetae, irregular rows present in elytral intervals; with weak transverse strigae; lateral margin with row of tiny, sawtooth-like setae. Mesoventral plate ( Fig. 9f ) notched anteriorly, extending posteriorly to metaventrite, dividing mesoventral disc in two, procoxal rests absent; mesanepisternum with incomplete transverse carina; mesocoxal cavities widely separate, separated by more than half width of a coxal cavity. Mesotarsomere III not bilobed. Metaventral process ( Fig. 9f ) not extending anteriorly beyond anterior level of mesocoxae; metaventral postcoxal lines diverging from mesocoxal cavity margin, smoothly rounded behind, without a spur; discrimen short, extending less than halfway to anterior margin of metaventral process; metendosternite ( Fig. 9g ) with anterior tendons moderately separated, ventral process intersecting ventral longitudinal flange behind anterior margin. Anterior margin of metacoxa with emargination sublaterally; metacoxal plate with transverse line; metafemur with subapical row of stout setae on posteroventral surface; metatibial foreface with apical ctenidium roughly perpendicular overall to long axis of tibia; spurs cylindrical, longest spur subequal to width of tibial apex; metatarsomere I shorter than metatarsomere II, joint between I and II rigid ( Fig. 9d ). Hind wing ( Fig. 9e ) with distinct, ovate anal lobe; leading edge with complete row of long setae at level of RA +ScP; AA 3+4 not apparent; cubitoanal system unbranched apically; CuA 2 and MP 3+4 with distal remnants; r4 present; flecks present in apical field just distal to rp-mp2; long transverse proximal sclerite and additional weak, irregular sclerite present just distal to end of radial bar.

Abdomen. Abdominal ventrite I without paired lines or calli; spiracles apparently absent from segment VII. Male with aedeagus upright in repose; tegmen ( Fig. 9h ) with symmetrical anterior margin, parameres fused to basal piece, though separated by from it by a faint suture, parameres with medial longitudinal division; penis ( Fig. 9i ) somewhat wedge-shaped, with endophallic spicules, with large sclerites, apex weakly pointed; spiculum gastrale V-shaped, with arms free. Female ovipositor weakly sclerotized, palpiform.

Immature stages. Unknown.

Bionomics. Unknown.

Distribution and diversity. Apparently endemic to Madagascar. I have seen several new species of Nesiotus from that island.

Included species (1):

Nesiotus olibroides Guillebeau, 1896 ( Distribution : Madagascar) (type!)

Discussion. See notes on the species originally described in Nesiotus by Scott (1922) in the Acylomus discussion.

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 9. Nesiotus n. 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). Nesiotus olibroides Guillebeau, lectotype male. (h) Tegmen, ventral; (i) penis, ventral (scale bar = 0.5 mm).

FIGURE 38. Photographs. Nesiotus n.sp.: (a) dorsal. Stilbus nr. apicalis, male: (b) dorsal; (c) ventral. Xanthocomus sp.: (d) dorsal; (e) ventral. Pseudolibrus sp.: (f) dorsal. Litostilbus testaceus: (g) dorsal; (h) ventral. Litostilbus sp., southeast Asia: (i) dorsal.