Scirtes flavohumeralis, Ruta, Rafal, 2008

Ruta, Rafal, 2008, Contribution to the knowledge of Seychellois Scirtidae (Coleoptera: Scirtoidea), Zootaxa 1913, pp. 49-68 : 61-64

Scirtes flavohumeralis sp. nov.

( Figs. 44–51 )

Type material (7 males, 13 females). Holotype, male. “ SEYCHELLEN: 16.-30.5. / Mahé, Ostküste / Anse au[x] Pins / 1996, leg. Schödl (1)” (printed label), “ HOLOTYPE / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” (red label, printed). Deposited in NMW. Paratypes. 1 female: “ SEYCHELLES / Mahe, iv.1976. / G. G. Kibby / B. M. 1976-237.” (printed label), “ Scirtes seychellensis / G. KIBBY / Det. 1976” (handwritten/ printed label), “ PARATYPUS / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” (red label, printed). Deposited in NHM. 3 males: “ SEYCHELLEN: 16.-30.5. / Mahé, Ostküste / Anse au[x] Pins / 1996, leg. Schödl (1)” (printed label), “ PARATYPUS / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” (red label, printed). Deposited in NMW. 1 male, 3 females: “ SEYCH., Mahé, 1992 / Anse aux Pins / 19.12., Malicky” (printed label), “Mangrove” (printed label), “ PARATYPUS / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” (red label, printed). Deposited in NMW. 3 females: “ SEYCHELLES: Silhouette / Grande Barbe / 15.03.2002 / leg. J. Gerlach” (printed label), “ PARATYPUS / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” (red label, printed). Deposited in NMW. 2 females: “ SEYCHELLES / Silhouette, Grande Barbe / 16.3.2002 / leg. J. Gerlach” (printed label), “ PARATYPUS / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” (red label, printed). Deposited in NMW and CUMZ. 1 female: “ SEYCH., Mahé, 1992 / Riv. du Cap / 10.12., Malicky” (printed label), “ PARATYPUS / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” (red label, printed). Deposited in NMW. 1 female: “ Seychelles, Praslin, / Anse Lazio, lagune / 5 m, 4.4.2007, / leg. Wewalka (4)” (printed label), “ PARATYPUS / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” red label, printed. Deposited in NMW. 1 female (damaged: head and pronotum missing): “ SEYCHELLES: Grande Soeur / 22.03.2002 / leg. J. Gerlach” (printed label), “ PARATYPUS / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” (red label, printed). Female, Deposited in NMW. 1 male: “ SEYCHELLES: Mahé Is. / Grand Police Bay. / 22.vii.1996. Sweeping. / OU Seychelles Expedition 1996 / OUMNH-2002-007” (printed label), “ Scirtes seychellensis / Det. M. Jäch 2005.” (printed label), “ PARATYPUS / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” (red label, printed). Deposited in OUMNH. 1 male, 1 female: “ SEYCHELLES: La Digue Is. / La Digue Veuve Reserve. / La Mare Soupape wetland. / 16-18.viii.1996. Hand collecting. / OU Seychelles Expedition 1996 / OUMNH 2002-007” (printed label), “ Scirtes seychellensis / Det. M. Jäch 2005.” (printed label), “ PARATYPUS / Scirtes flavohumeralis sp. n. / des. Rafał Ruta 2008” (red label, printed). Deposited in OUMNH.

Diagnosis. Fully pigmented adults with yellowish humeral area, remaining portion of elytra brownish.

Females with oval, oblique depressions at apices of elytra. Several externally similar species occur in SE Asia. Certain identification is possible only on the basis of the morphology of male and female genitalia (strongly modified aedeagus; ring-shaped bursal sclerite).

Description. Holotype, male. Measurements: TL 1.95, EW 1.35, EL 1.68, PW 1.0, PL 0.38, HW 0.65, HL 0.28, interocular space 0.4, greatest depth of body 0.6.

Body oval, flattened, and covered with yellowish hairs. Head, pronotum and scutellum yellowish, elytra brownish, with lighter, yellowish basal portion and humeri, ventrum light, yellowish. Legs yellowish, antennae yellowish, slightly darkened apically. Body 1.44 times as long as broad.

Head 2.36 times as broad as long, 1.63 times wider than interocular space, with subtle punctures separated by 0.5–0.7 diameter, eyes moderately protuberant. Antennae filiform, antennomere 1 and 2 wider than remaining ones, cylindrical, antennomere 3 shortest, antennomere 4 longest; length ratios of antennomeres 2.67: 2.0: 1.0: 2.0: 2.67: 2.67: 2.67: 2.67: 2.67: 2.67: 3.33; L/W ratio of antennomeres 1.33, 1.2, 1.5, 1.5, 2.0, 2.0, 2.0, 2.0, 2.0, 2.0, 2.5. Clypeus transverse, with rounded anterolateral angles and somewhat explanate lateral edges. Labrum very small, with rounded anterior angles, partly hidden under clypeus. Mandibles with explanate and tapered apices, without mesal denticles.

Pronotum small, transverse, 2.67 times as broad as long, widest at posterior angles. Pronotum with subtle but dense punctation similar to that of head, punctures separated by a single diameter. Posterior margin of pronotum bisinuate. Anterior angles slightly explanate. Scutellum subtriangular, punctation similar to that on pronotum.

Elytra oval, without longitudinal ridges, 1.24 times as long as broad and 4.47 times as long as pronotum. Sides rounded in posterior third, regularly converging to apex. Humeri evident. Punctures evenly larger than those of head and pronotum, distance between punctures = 0.5 diameter. Epipleura wide at base, abruptly narrowed near ventrite 1, reduced in apical portion. Hind wings fully developed.

Prosternal process elongate, laminar, forming a sharp ridge. Mesocoxae separated by an extremely narrow and long process with subparallel sides (ca. 6 times as long as wide), metaventral discrimen present in posterior 3/4. Metacoxae touching one another. Last ventrite with shallow subtriangular emargination. Ventrite 2 with a few larger punctures along mesal portion of anterior margin, last ventrite with 2 small teeth in posterior area. Ratios of ventrites’ lengths: 1.0: 1.5: 1.5: 1.5: 1.8. Metafemora enlarged, ca. 5 times broader than metatibia. Metatibial spurs present, longer as long as 0.7 length of 1st tarsomere, slightly curved. Shorter spur slightly curved, as long as 0.3 length of tarsomere 1 and 0.4 length of longer spur.

Male genitalia. Aedeagus (L 0.68, W 0.38) strongly modified, in the form of ring with 4 tempered projections; sternite 9 small (L 0.2, W 0.15), Y-shaped, with long setation on apices; tergite 8 (L 0.28, W 0.23) with short apodemes and row of setae on apex; tergite 9 (L 0.24, W 0.15) with relatively long apodemes and setae on apex.

Female. Apical portion of elytra modified, with oblique, elongate-oval depressions. Prehensor (L 0.35) tubular, short; bursal sclerite (L 0.08, W 0.13) ring-shaped, with small projection pointed inwards; ovipositor long (L 2.0); terminal segments long: sternite 8 L 0.55, tergite 8 L 1.15.

Variability. Total length of males 1.7-2.1 (mean 1.96, n=7), total length of females 1.95–2.2 (mean 2.04, n=11). Body varies from uniformly yellow with poorly visible lighter humeri to brownish with clearly visible and contrasting light-yellow humeral region.

Name derivation. Referring to lightened humeri of the typical form.

Remarks. Modifications of the elytral apices in females of Scirtidae were described for the first time by Champion (1897) and the analogy to the similar (although present in males) structures in Melyridae : Malachiinae was immediately noticed. Champion (1918) described modifications (foveae or excavations) in the genera Scirtes Illiger, 1807 , Ora Clark, 1865 and Cyphon Paykull, 1799 . The use of the term “excitator” is proposed here (by analogy to the name of similar structures in Malachiinae ) to designate the modifications of the elytra in females of the family Scirtidae . The function of the excitators is presently unknown, although observations on mating behaviour of Cyphon coarctatus Paykull, 1799 suggest that modified adscutellar areas of elytra in this species play a role in stimulation of male before copulation ( Nyholm 1972). It seems highly probable that modified portions of elytra secrete sexual pheromones.

Figures

FIGURES 44 – 49. Scirtes flavohumeralis sp. nov. 44) male, habitus; 45) female, close-up of elytra; 46) aedeagus; 47) sternite 9; 48) tergite 8; 49) tergite 9. Scale bar = 0.2 mm (for Figs. 46 – 49).

FIGURES 50 – 51. Scirtes flavohumeralis sp. nov. 50) female genitalia; 51) prehensor and bursal sclerite, close-up.