Mesene leucogyna Hall & Lamas

Hall, Jason P. W. & Lamas, Gerardo, 2007, Four new symmachiine taxa from the eastern Andes of Peru and Ecuador (Lepidoptera: Riodinidae), Zootaxa 1533, pp. 41-52 : 41-46

Mesene leucogyna Hall & Lamas , new species

(Figs. 1A,B; 5; 9)

Description: Male: Forewing length 13 mm. Forewing costa approximately straight, distal margin slightly convex, four forewing radial veins; hindwing round. Dorsal surface: Ground color of both wings dark orange; forewing with narrow black costal and distal margins, broadening at apex; hindwing with narrow black costal, distal and anal margins; fringe on both wings entirely black. Ventral surface: Ground color of both wings dirty white, with a hint of very pale orange from dorsal surface, becoming grayish along anal margin of hindwing; forewing with very broad dark brown margins distally and along costa, including upper half of discal cell; hindwing with very broad dark brown margins distally and below costa, and a very narrow whitish strip along basal two-thirds of costal wing margin.

FIGURES 1–4. Symmachiini adults (dorsal surface on left, ventral surface on right). 1A. Mesene leucogyna leucogyna Hall & Lamas , n. sp., holotype ɗ, Qbda. Siete Jeringas, Junín, C. Peru (MUSM). 1B. M. leucogyna leucogyna , putative Ψ, Yakunk-Cutucú trail, Morona-Santiago, S. Ecuador (JHKW). 2A. Mesene leucogyna notia Hall & Lamas , n. ssp., holotype ɗ, San Pedro, Cuzco, S. Peru (USNM). 2B. M. leucogyna notia , paratype Ψ, San Pedro, Cuzco, S. Peru (MUSM). 3A. Mesene margaretta anartia Hall & Lamas , n. ssp., holotype ɗ, Aldea, Junín, C. Peru (MUSM). 3B. M. margaretta anartia , paratype Ψ, Pakitza, Madre de Dios, S. Peru (USNM). 4. Symmachia pena Hall & Lamas , n. sp., holotype ɗ, Qbda. Siete Jeringas, Junín, C. Peru (MUSM).

Head: Labial palpi a mixture of dark brown and whitish scaling, second and third segments short; eyes brown and bare, lateral scaling dark brown; frons dark brown, with whitish scaling laterally and ventrally; antennae approximately 70% of forewing length, antennal segments black with a discontinuous nudum section lateroventrally, clubs black.

Body: Dorsal surface of thorax prominently dark orange, ventral surface grayish; dorsal surface of abdomen dark orange, lateral margins dark brown, ventral surface grayish; a broad and continuous band of con cealed androconial scales present dorsally across posterior margin of abdominal tergites four, five and six; forelegs whitish, mid- and hindlegs predominantly dark brown.

Genitalia ( Fig. 5 ): Uncus angular in lateral view, with a short posterior projection from dorsal middle of posterior margin, falces with a prominent angular “elbow”, tegumen typical of tribe; vinculum an evenly narrow diagonal ribbon, saccus anteriorly elongate and ventrally rounded; valvae short and medially divided into a slightly larger, triangular upper section, with an uneven dorsal margin and a slightly upturned, rounded posterior tip, and a vertically elongate lower section, with a narrowly pointed and slightly downwardly curved posterior tip; aedeagus short, broad and bent medially at nearly 90°, posterior tip angular and ill-defined with respect to vesica, rounded anterior tip opens to left, single cornutus a long, broad, sclerotized band, with three or four prominent triangular spines along posterior portion of dorsal margin (when vesica everted); pedicel broad in basal and posterior sections, but medially constricted and bent beyond 90°.

Putative female: Forewing length 14.5 mm. Forewing costal margin approximately straight, distal margin prominently convex; hindwing round. Dorsal surface: Ground color of both wings white; costal margin and distal half of forewing black, distal third of hindwing black, distal margin of white areas on both wings rounded; fringe on both wings entirely black. Ventral surface: Same as dorsal surface, but slightly paler. Head: Same as male, but nudum on antennal segments continuous.

Body: Dorsal and ventral surfaces of thorax black with some white scaling; dorsal and lateral surfaces of abdomen black, ventral surface a mixture of black and white scaling; no abdominal androconia present; all legs predominantly dark brown.

Genitalia ( Fig. 9 ): Corpus bursae slightly elongate and rounded, with a pair of invaginated, spine-like signa at posterior wall; ductus bursae mostly evenly narrow, abruptly becoming broader immediately before ostium bursae, ductus bursae membranous except for a small portion of sclerotization at point of broadening, membranous ductus seminalis exits right ventral side of ductus bursae at posterior margin of sclerotized area; ostium bursae consists of a rectangular band of broad sclerotization that is constricted at middle of posterior margin and flares laterally at anterior corners, and has a pair of narrowly elliptical concave areas dorsolaterally.

Type material: Holotype ɗ, PERU: Junín, Quebrada Siete Jeringas, 1700 m, 11°12’S 75°24’W, 13 Nov 2003 (C. Peña ) (Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima, Peru [ MUSM]).

No additional male specimens of this taxon have been located in the world’s major collections. The specimen described and illustrated here from the Yakunk-Cutucú trail, in Morona-Santiago province, southern Ecuador, as the putative female of this taxon is not designated as a paratype because of the distance of its capture location from the type locality and slight wing pattern differences, leaving the possibility that it may belong to yet another undescribed subspecies of M. leucogyna .

Etymology: The name of this species has been derived from combining the Greek words for “white” and “female”, in reference to its highly sexually dimorphic black and white patterned female.

Diagnosis: This new species possesses the concealed androconial scales diagnostic of the Symmachiini ( Harvey, 1987) on male abdominal tergites four, five and six, a character state that is shared only with the species of Mesene , the two species of Chimastrum Godman & Salvin, 1886 , and Esthemopsis crystallina Brévignon & Gallard, 1992 ( Hall & Harvey, 2002) . By having small, compact and rounded wings, an orange and black patterned male, and no black spotting, leucogyna can be placed in the genus Mesene .

By sharing similar male wing patterns, and very similar male and female genitalia, the Andean M. leucogyna can confidently be placed as sister to the allopatric lowland sister species pair (as first determined by Hall & Harvey, 2002) of Mesene nepticula Möschler, 1877 (Amazonia) , and Mesene simplex Bates, 1868 (southeastern South America). The male genitalia of these three species have the same unique valve shape, and the genitalia of the two lowland species differ significantly from those of M. leucogyna only by having a shorter sclerotized pad on the everted vesica that lacks distal spines. The female genitalia of the three species do not differ significantly. Of the two lowland relatives, M. simplex has the most similar male to that of M. leucogyna because it is also almost entirely orange, lacking the isolated white or orange forewing subapical spot of M. nepticula . The male of M. leucogyna (from both the nominotypical subspecies and the subspecies described below) differs externally from that of M. simplex by being slightly larger, and by having a frons, palpi and legs that are dark brown to black with some white scaling instead of predominantly orange, a ventral abdominal surface that is grayish instead of pale orange, slighter broader black borders on both wings, black scaling along the anal margin of the hindwing, a broad subcostal black border on the ventral hindwing, and no traces of white marginal markings in ventral hindwing cells Cu2, M3 and M2. The only sympatric congener with which M. leucogyna might be confused is M. cyneas (Hewitson, 1874) . However, both sexes of M. cyneas differ externally from the male of M. leucogyna by having an entirely black thorax, abdomen and frons, black instead of whitish to cream forelegs, mid- and hindlegs that are half black and half orange, white fringe scaling in the forewing apex, considerably broader black borders on both wings, no black scaling along the anal margin of the hindwing, and no subcostal black border on the ventral hindwing. The female of M. leucogyna is unique within Mesene in being black and white. Indeed it does not closely resemble any phenotype within the Symmachiini . Perhaps the most similar riodinid butterfly is the female of Machaya watkinsi (D’Abrera, 1994) (incertae sedis section) (a novel combination discussed by Hall, 2007), a species that is sympatric with M. leucogyna in the southern Andes. However, the female of M. watkinsi is readily distinguished from that of M. leucogyna by having an angular hindwing, a variably faint white subapical forewing band, and a basal white forewing patch that is medially divided by a horizontal black line and suffused with yellow along its costal margin.

It is worth reiterating here that Mesene bigemmis Stichel, 1925 (with its synonyms fissurata Stichel, 1929, and arouany Brévignon, 1998) is not a synonym of Mesene nepticula stigmosa Stichel, 1910 , as indicated in the recent catalog of Callaghan & Lamas (2004), but an unrelated species belonging to the Mesene phareus group (with very different male genitalia), as clearly indicated by Hall & Harvey (2002) (rev. stat.).

Biology: This very rare taxon appears to be confined to montane forest habitats, where it is currently known from between 1350 and 1700 m. The male holotyp e was observed resting about 6 m above the ground in a forest lightgap. The only known putative female was collected at 1445 hrs flying across an open ridgetop lightgap about 3 meters above the ground (K. Willmott, pers. comm.). Males of the superficially similar but unrelated Mesene cyneas were perching in the same lightgap at that time.

Distribution: Mesene leucogyna leucogyna is currently known with certainty only from the type locality in the central Peruvian department of Junín, but may range at least as far north as central eastern Ecuador if the figured female truly belongs to nominotypical M. leucogyna , rather than another undescribed subspecies. This taxon appears to be replaced in the southern Andes by M. leucogyna notia .

Figures

FIGURES 5 – 8. Symmachiini male genitalia in lateral view. 5. Mesene leucogyna leucogyna, holotype %, Qbda. Siete Jeringas, Junín, C. Peru (MUSM). 6. Mesene leucogyna notia, holotype %, San Pedro, Cuzco, S. Peru (USNM). 7. Mesene margaretta anartia, paratype %, Pakitza, Madre de Dios, S. Peru (MUSM). 8. Symmachia pena, holotype %, Qbda. Siete Jeringas, Junín, C. Peru (MUSM). Scale bar = 1 mm.

FIGURES 9 – 10. Symmachiini female genitalia in dorsal view. 9. Mesene leucogyna leucogyna, putative Ψ, Yakunk- Cutucú trail, Morona-Santiago, S. Ecuador (JHKW). 10. Mesene leucogyna notia, paratype Ψ, San Pedro, Cuzco, S. Peru (MUSM). Scale bar = 1 mm.