Pusiola unicolor Durante, 2022

Durante, Antonio & Apinda-Legnouo, Emelie Arlette, 2022, Fifth contribution to the study of the Lithosiini of Gabon: two genera new for Gabon, with a description of two new species (Lepidoptera: Erebidae: Arctiinae), Zootaxa 5091 (3), pp. 416-428 : 418-419

Pusiola unicolor Durante new species

( Figs 1–4 , 9 , 10 )

Holotype: ♂, GABON, Ipassa (Makokou), 500 m, 0°30’43”N 12°48’13”E, 18/ 20-11-2017, Durante leg., gen. sl. n. 989 MAD; in coll. MSNS.

Paratypes: 7 ♂♂, same data as the holotype ; 5 ♂♂, same locality as the holotype, 4/ 13-12-2013 ; 1 ♂, same locality as the holotype, 14/ 24-3-2015 ; 3 ♂♂, same locality as the holotype, 19/ 24-11-2017 ; 8 ♂♂, same locality as the holotype, 21/ 22-11-2017 ; 3 ♀♀, same data as the holotype ; 2 ♀♀, same locality as the holotype, 5/ 10-4-2010 ; 7 ♀♀, same locality as the holotype, 19-2/ 11-3-2011 ; 1 ♀, same locality as the holotype, 16/ 28-2-2012 ; 3 ♀♀, same locality as the holotype, 4/ 13-12-2013 ; 14 ♀♀, same locality as the holotype, 14/ 24-3-2015 ; 3 ♀♀, same locality as the holotype, 18/ 20-11-2017 ; 5 ♀♀, same locality as the holotype, 19/ 24-11-2017 ; 14 ♀♀, same locality as the holotype, 21/ 22-11-2017 ; all Durante leg. 4 ♀♀, same locality as the holotype, 14/ 25-6-2016 , Durante & Fasiello leg. All in the first author’s collection.

Diagnosis. The absence of a discal dot on the forewings distinguishes Pusiola unicolor n. sp. from Pusiola celida and Pusiola cinerella ( Wallengren, 1860) ; the pale shades of yellow (creamy, ochreous, ivory) or light grey of the majority of the congeneric species are diagnostic compared to the dark grey-brown colour of P. unicolor n. sp. The only species that could require comparison of the genitalia are P. flavicosta ( Wallengren, 1860) and P. tinaeella ( Kiriakoff, 1958) . The former however possesses a yellow line along the forewing’s costal margin, absent in P. unicolor n. sp.; the latter is generally paler than unicolor n. sp. In any case, the following genital apparatus characters are diagnostic.

Comparing P. flavicosta and P. tinaeella with P. unicolor n. sp. the differential characters are as follows: i) the valva and uncus of P. unicolor n. sp. are longer and more slender; ii) the juxta is L-shaped and protrudes caudally, while it is trapezoid and flat in flavicosta , and X-shaped and flat in tinaeella ; iii) the saccus is larger and u-shaped in P. unicolor n. sp., with a larger median notch, while it is slender and bifid in flavicosta and tinaeella ; iv) the aedeagus of P. unicolor n. sp. bears only granicula (graniculi in Birket-Smith (1965); see also Tuxen (1970) on the neuter grammatical gender of this noun) on the vesica, while there are granicula and a large thorn-like cornutus in flavicosta and tinaeella .

Description. Wingspan ♂ 17.5–19 mm; ♀ 19-21 mm.

Head frons and vertex, notum including patagia and tegulae, and abdominal tergites all same colour as forewing upperside or slightly darker; clypeus always darker; antennae ciliated (cilia longer in the male, Figs. 9A, 9B ), dorsally same colour as the vertex, ventrally unpigmented; labial palpi porrect, not extending beyond the frons, as dark as the clypeus or even darker.

Thorax. Thoracic sternites as dark as the forewings underside; legs same colour, with the dorsal face of the first two pairs darker; spurs formula 0-2-4. Forewing upperside ground colour grey-brown, with a faint, very small dark vaguely triangular mark half way along the costa; a few specimens slightly darkening towards the termen. Forewing underside slightly darker than the upperside, anal area paler. Hindwing upperside slightly darker than or same colour as the forewing upperside; costal area sometimes paler. Hindwing underside same colour as the upperside. Fringes concolorous.

Abdomen. Abdominal sternites as dark as thoracic sternites; abdominal scales slightly darker along the pleurae; anal tuft paler; male with the eighth abdominal segment very short, about ¼ the length of the seventh, anteriorly forming shallow double-dimple-like coremata ( Fig. 9D ), and latero-posteriorly two dome-shaped projections ( Fig. 9D ); female with seventh abdominal segment slightly sclerotized, one and a half times longer than the sixth ( Fig. 10E ), and eighth abdominal segment the same length as the sixth, slightly sclerotized, with a V-shaped membranous notch in the middle of the sternum.

Genitalia. ♂. Uncus pointed, long and slender, bent slightly backwards; tegumen pear-shaped in dorsal view, with fairly large pedunculi (sensu Diakonoff 1939); vinculum slender, U-shaped, but with the saccus notched at the ventro-cephalic end; juxta protruding caudally, more or less axe- or L-shaped with the handle pointed, dorsally directed; valvellae appearing as weak, not clearly delimitated sclerotizations, ventro-laterally with respect to the juxta. Valva slender compared to the typically stouter Pusiola valvae (e.g. P. flavicosta ); distal half of the supravalva flap-like, sub-oval, ending proximally with a curved processus distalis plicae ( Fig. 10A ); ala valvae with slender proximal portion (sacculus) and pointed distal process, long, slender and strongly sclerified, imperceptibly distally exceeding the supravalva. Aedeagus about three times longer than wide, tubular, with an undelimited flat sclerotization at the dorsal distal end, coecum penis sub-conical, ductus seminalis inserted dorsally, vesica with globular general appearance, and a distal and a ventral lobus covered in oval-shaped scobinate granicula ( Fig 10D ).

Female. Caudal ventral margin of the seventh abdominal segment curly and dense (lamella antevaginalis, Fig. 10E ); eighth segment as long as the sixth, slightly sclerotized, with no lamella postvaginalis; papillae anales gently tapering caudally; posterior apophyses slightly longer and more slender than the anterior ones; anterior apophyses somewhat longer than the eighth segment; dorsal pheromone glands unpaired, with one caudal opening at the intersegmental membrane between A8 and A9, anteriorly bifurcated into two fairly narrow lobes not exceeding the posterior apophyses ( Fig. 9C ).

Ostium bursae as an inconspicuous opening medially in the intersegmental membrane between A7 and A8; antrum thick and short, truncated cone-shaped, with many thin spicules in the wall ( Fig 10F ); ductus bursae absent; corpus bursae oval, membranous, with a dense scobination of thorn-like spicules in the tissue of the wall, thicker than those of the antrum. Thorn-like spicules are of two sizes: thinner and denser along the caudal 2/3 of the corpus ( Fig 10H ), stronger and more dispersed along the anterior 1/3 ( Fig. 10G ); no signa; appendix bursae conical, membranous, caudally with respect to the corpus bursae, the ductus seminalis initiating at the posterior part ( Fig. 10E ).

Etymology. The name unicolor (meaning “of the same colour”) refers to the usually identical colour of the fore- and hindwings.

Remarks. In this species, the morphology of the male genitalia diverges in some way from the typical pattern of the genus (i.e. from the type species P. flavicosta ): in the new species presented above the uncus is slender, long and almost straight, whereas in most of Pusiola species it is stouter (i.e. shorter and less slender), and is caudally curved; the valvae are proportionally longer; the tegumen is twice as long as the vinculum (in other Pusiola species , valvae are nearly of the same length); the juxta is projecting sharply backwards. However, other characters allow us to at least tentatively include this species in the genus Pusiola , such as the overall size of the adult; shape of the wings (slightly broader than other Lithosiina genera); the general structure of the genitalia (curved process of the ala valvae, presence of the processus distalis plicae, notched saccus); and the presence of a subapical spur at the distal end of the aedeagus (in P. unicolor n. sp., the subapical spur has the shape of a flat apical sclerotization).The wing venation fits Hampson’s description (1900) for the genus, with the only exception being the apical veins in the forewing: in flavicosta is [Rs2(Rs3, Rs4)]M1, whereas in unicolor n. sp. it is [Rs2, Rs3) Rs4]M1 ( Fig. 9E ). In addition, it should be remarked that the new species does not fit well within any other genus in Africa ( De Toulgoët 1984; Krüger 2015), or even in South-East Asia. Holloway (2001) for instance, indicates the cases of similarity, e.g. Lambula fuliginosa ( Walker, 1862) with Euconosia xylinoides ( Walker, 1862) . Neither of both species are considered to be related to unicolor n. sp. Despite a similar uncus and bilobed saccus in all three species mentioned above, there are significant diagnostic differences: males of Lambula fuliginosa possess i) a folding on the costa of forewing, ii) a small tuft of scales on costal area of the hindwing (Holloway 2001: 298), iii) a process on the ala valvae bending over the supravalva, iv) socii present, v) a slender aedeagus and a slender cornutus. Similarly, despite the similar uncus and bilobed saccus, Euconosia xylinoides differs by: i) differently-shaped forewings, ii) distal margin of supravalva with dense hairs, iii) stout process on the ala valvae rises from a lower position than in Pusiola species , iv) presence of slender aedeagus and vesica with at least one long lobus in Euconosia species.

Ultimately, it should be stressed that the placement of P. unicolor n. sp. into the genus Pusiola has to be considered somewhat doubtful at least until a robust and contemporary revision of the genus is done.

Figures

FIGURE 9. Pusiola unicolor n. sp.—A: central segment of the antennal flagellum, male; B: central segment of the antennal flagellum, female; C: dorsal pheromone gland; D: acrosternite; E: forewing venation; F: hindwing venation. A: anal vein; co: coremata; CuA: Anterior cubital vein; dp: dome-shaped projections; M: median vein; pg: dorsal pheromone glands; R: radial vein; Rs: radial sector vein; Sc: subcostal vein; VIII st: eighth sternum.

FIGURE 10. Pusiola unicolor n. sp.—A–D: male genitalia. A: processus distalis plicae, enlarged; B: genitalia, aedeagus removed; C: aedeagus, vesica everted; D: granicula of the vesica, enlarged. E–H: female genitalia. E: genitalia; F: enlarged spicule of the antrum; G: enlarged spicule of the foremost part of the corpus bursae; H: enlarged spicule of the medio-caudal part of the corpus bursae. aa: anterior apophyses; ab: appendix bursae; ae: aedeagus; an: antrum; ap: posterior apophyses; av: ala valvae; cb: corpus bursae; cp: coecum penis; dl: distal lobus; fs: dorsal flat sclerotization of the aedeagus; gr: granicula; ju: juxta; pa: papillae anales; pav: distal process of the ala valvae; pd: processus distalis plicae; pe: pedunculi; pg: dorsal pheromone glands; sa: saccus; sv: supravalva; te: tegumen; un: uncus; ve: vesica; vi: vinculum; VII st: seventh sternum; VIII st: eighth sternum; vl: ventral lobus.

FIGURES 1–8. Lithosiini spp.: adults. 1, Pusiola unicolor n. sp.—holotype male. Gabon, Ivindo National Park. 2, ditto—paratype, male. Gabon, Ivindo National Park. 3, ditto—paratype, female. Gabon, Ivindo National Park. 4, ditto—paratype, female. Gabon, Ivindo National Park. 5, Pusiola celida—male. Gabon, Mondah forest. 6, Novilema bifurcum n. sp.—holotype, male. Gabon, Ivindo National Park. 7, Novilema fluminale—male. Gabon, Ivindo National Park. 8, ditto—male. Gabon, Ivindo National Park.