Synarmostes monoculus, Ballerio, 2021

Ballerio, Alberto, 2021, The Ceratocanthinae of Madagascar and Comoro Islands: a revision of the genera Synarmostes and Goudotostes, and of the flightless Philharmostes, with description of 64 new species (Coleoptera: Scarabaeoidea, Hybosoridae), Fragmenta entomologica 53 (2), pp. 105-282 : 160-161

Synarmostes monoculus sp. nov.

( Figs 18 e-h, 31 m-o, 35) http://zoobank.org/ urn:lsid:zoobank.org:act:0F5561B7-1A77-4314-9C16-EA6A8F0551EF

Type series. Holotype, ♂, deposited in the collection of the California Academy of Sciences , San Francisco, CA, USA, labelled as follows: / CASTYPE 20257 / Madagascar: Majunga Réserve forestière Beanka 52.7 Km E of Maintirano el. 300 m 24-27 Oct. 2009 / 18° 03’ 44” S 044° 31’ 33” E California Acad. of Sciences coll. B. L. Fisher et al. tropical dry forest on tsingy sifted litter BLF22925/ Synarmostes monoculus n. sp. det. A. Ballerio 2020 Holotypus ♂ / [distended, glued on card, dissected, male genitalia glued in DMHF resin on a separate card, same pin]. Paratypes [1 ♂ dissected]: 1 ♂ ( CASC), same collecting data as holotype .

Diagnosis. Synarmostes monoculus sp. nov. can be differentiated from all other species of Synarmostes by the following combination of characters: a) small size, b) ventral ocular area small-sized, c) dorsal ocular area vestigial, d) dorsal setation absent (20×), e) flightlessness, f) carinae of elytral apical third regular (without tubercles or other irregularities), g) scutellum with transverse comma-shaped punctation, h) pronotal punctation consisting of transverse comma-shaped punctures, i) pronotum without an anteromedian area smooth or with very sparse punctation, j) head with dense and impressed simple punctation, k) elytra with small transverse sparse comma-shaped punctures mixed to some horseshoe-shaped punctures. Synarmostes monoculus sp. nov. belongs to the antsingyi group of species and is very similar to S. antingyi sp. nov., from which differs mainly because of the presence of uniform punctation on pronotal disc and the vestigial dorsal ocular area and to S. beankae sp. nov., from which differs because of the smaller elytral punctation and the vestigial dorsal ocular area.

Description. Size: HL = 0.6 mm; HW = 1.1 mm; PL = 1.0 mm; PW = 1.8 mm; EL = 1.9 mm; EW = 1.8 mm. Overall morphology as in generic diagnosis. Small-sized flightless Synarmostes . Body convex. Dark-brown with bronze sheen, shiny, dorsum glabrous (20×), underside, tarsi and antennae reddish-brown, setation yellowish-brown. Head: W/L ratio = 1.40, clypeal apex obtuse, apical projection small but distinctly protruding and sharp; dorsal ocular area absent (probably vestigial: a hint of eye visible in transap- rence only), inferior ocular area small; head dorsal surface, except from smooth vertex, uniformly covered by large impressed dense simple punctures (interpunctural distance about twice to thrice the diameter of each puncture), a distinctive deep curved line is present just below the gena on the spot where the dorsal ocular area is normally present. Fore margin with one or two irregular rows of long transverse lines. Vertex smooth with one continuous transverse impressed line. Pronotum: subrectangular (W/L ratio = 1.88), regularly convex, pronotal surface almost uniformly punctured, only sides and base almost impunctate; punctures short transverse comma-shaped, each one bearing a simple puncture internally, curvature centripetally orient- ed. Interpunctural distance once to three times longer than punctural width.

Scutellum : with some transverse comma-shaped punctures. Elytra: longer than wide (W/L ratio = 0.90); subovoidal (dorsal view); inferior sutural stria reaching humeral area although under the form of a very shallow fine line; humeral callus indistinct; elytral surface regularly convex, uniformly covered by sparse punctation. Interpunctural distance once or twice the maximum width of punctures. Punctures comma-shaped becoming horseshoe-shaped on apical third, small and transverse, each one having a simple setigerous puncture internally. Elytral distal third with eight raised longitudinal carinae (excluding elytral suture), sometimes having a longitudinal shallow line among them. Wings: flightless (apterous). Male genitalia: aedeagus (L = 0.8 mm) with parameres as in Figs 31 m-n, spiculum gastrale (L = 0.8 mm) as in Fig. 31 o .

Etymology. Latin adjective in the nominative singular meaning “with a single eye”, due to the absence of the dorsal ocular area.

Distribution and habitat. Known only from the type locality in western Madagascar. The type series was collected by sifting litter (leaf mold, rotten wood) on a Tsingy in tropical dry forest. See under S. beankae sp. nov. for further details.

Figures

Fig. 18 – Synarmostes caterinae sp. nov., a, dorsal view of distended holotype; b, ventral view of rolled up paratype; c, dorsal view of rolled up paratype; d, lateral view of rolled up paratype; Synarmostes monoculus sp. nov., e, dorsal view of distended holotype; f, ventral view of rolled up paratype; g, dorsal view of rolled up paratype; h, lateral view of rolled up paratype.

Fig. 31 – Aedeagi and spicula gastrales, a–c, Synarmostes antsingyi (Tsingy de Bemaraha); d–f, Synarmostes beankae sp. nov., holotype; g–i, Synarmostes bekaraokae sp. nov., holotype; j–l, Synarmostes caterinae sp. nov., holotype; m–o, Synarmostes monoculus sp. nov., holotype.