Vettius mitsuko Nakahara, Nakamura & MacDonald, 2020

Nakahara, Shinichi, Anderson, Richard A., Nakamura, Ichiro & MacDonald, John R., 2020, An integrative taxonomic approach supports a new species of Vettius from Central America (Lepidoptera: Hesperiidae: Hesperiinae), Journal of Natural History 54 (27 - 28), pp. 1699-1711 : 1701-1706

Vettius mitsuko Nakahara, Nakamura & MacDonald , new species

( Figures 1–5 )

Systematic placement and diagnosis. Vettius mitsuko n. sp. is supported as sister to Vettius phyllus , the type species of the genus, with a strong support (SH-aLRT/aBayes/ UFBoot = 99.5/1/97; Figure 1 ) based on the maximum likelihood tree (LnL = −2621.466; Figure 1 ). Vettius chagres is strongly supported as sister to these two species (SH-aLRT /aBayes/UFBoot = 94.8/0.998/96; Figure 1 ). The mean genetic distance between three individuals of V. mitsuko n. sp. and two individuals of V. chagres was 0.9%. The mean infraspecific distance among the three specimens of V. mitsuko n. sp. was 0%, and between the two sequenced V. chagres was also 0%. The forewing of V. mitsuko n. sp. appears to serve as a diagnostic character to separate this species from two closely related taxa, V. phyllus and V. chagres , by its greater length (see Figure 4 ). Phenotypically, Vettius mitsuko n. sp. is readily distinguished from V. phyllus and V. chagres by its reduced whitish macules on the dorsal hindwing cells M1, M2, and M3 (completely absent in cell M1, see also description below), whereas the whitish macules occupy at least one-third of these cells in V. phyllus and V. chagres . The whitish streak in the dorsal hindwing cell Cu2 also appears to be reduced in V. mitsuko n. sp. compared to V. phyllus and V. chagres , thus overall giving the impression of ‘darker’ dorsal hindwing as compared with these two species. The ventral hindwing is also different in V. mitsuko n. sp. in lacking the silverish streak in cell Cu2, whereas this streak is clearly visible in V. phyllus and to a lesser extent V. chagres . Vettius mitsuko n. sp. lacks the small silver marking in cell M1 of the ventral hindwing, whereas this marking is visible in V. chagres . The orangeish area posterior of ventral hindwing 2A is wider in V. mitsuko n. sp. compared to V. phyllus , whereas V. chagres lacks this orangeish colouration. The orangeish band extending from the base of the discal cell to cells M2 and Cu 1 in V. mitsuko n. sp. is absent in V. phyllus ; in V. chagres the orangeish colouration does not reach the distal side of cell Cu1 and appears somewhat restricted to the base of the ventral hindwing compared to V. mitsuko n. sp. The male genitalia of V. mitsuko n. sp. is different from these two species by having a narrow and longer saccus, which is similar to the valva in length, but in both V. phyllus and V. chagres , the length of saccus is approximately half of the valva in length. Although the valva shape of V. mitsuko n. sp. and V. chagres are not distinguishable, the valva shape of V. mitsuko n. sp. and V. phyllus appears to have stable differences, namely V. mitsuko n. sp. having less concaved distal margin of valva compared to more strongly concaved distal margin of valva seen in V. phyllus , as illustrated in Figure 4 . Finally, it is important to note that our diagnosis is based solely on examination of male specimens, since we are unaware of any female individuals of V. mistuko n. sp. to our knowledge.

Description

MALE. Forewing length 20.5–23 mm (mean 21.5 mm; n = 4)

Head. Eyes black and naked (no visible hair-like setae), creamy white elongated scales and hair-like scales, as well as greyish elongated scales present at base; frons with dark brownish long hair-like scales and viridian semi-iridescent scales; labial palpi overall length approximately 4 mm (n = 1), first segment short, with white scales and black hairlike scales ventrally in lateral view, black scales present interiorly, second segment length similar to eye diameter, dorsally with black scales and black hair-like scales with whitish scales visible anteriorly, laterally roughly blackish above and whitish below, ventrally with whitish scales and hair-like scales with anterior portion mixed with black scales, dense in black scales interiorly mixed with white scales anteriorly, third segment short, porrect, covered with black scales, most of third segment visible in lateral view but appearing as extending just beyond anterior scales of second segment in ventral view; antenna about two-third of forewing in length, covered with brownish scales with semi-iridescent viridian scales visible on ventral side, apiculus hooked, appearing brighter with light ochre scales ventrally on clava (i.e. club), nudum ca. 12 antennomers.

Thorax. Dorsally black scattered with dark greyish scales, orangeish long hair-like scales visible on prothorax, laterally adorned with silver-blue long hair-like scales, ventrally (i.e. below wings) with orangeish long hair-like scales and whitish long hair-like scales; fore-leg femur black with semi-iridescent olive scales visible dorsally and ventrally whitish, tibia without spurs and spines but with tibial epiphysis, tarsus ventrally with few longitudinal rows of spines; mid-leg femur black dorsally and whitish ventrally, tibia dark olive dorsally with brown setiform scales and greyish ventrally, tibia adorned with row of six spines ventrally and pair of spur at distal end (inner spur longer than outer spur), tarsus colour pattern similar to tibia, spines on ventral surface appearing shorter and more densely placed in few rows compared to tibia; hind-leg similar to mid-leg except for presence of additional pair of tibial spur roughly in middle of tibia on ventral surface (these spurs shorter than those at distal end).

Abdomen. Dorsally and laterally overall dark brownish with mix of blueish-white long hair-like scales and dark brownish long hair-like scales, semi-iridescent viridian scales present partially, posterior end with light brownish long hair-like scales and white long hair-like scales, ventrally whitish with longitudinal dark brown stripe in middle.

Wing venation. Forewing discal cell length approximately 60% of forewing length, dcs short, origin of M2 close to M3 than M1 (i.e. dcm longer than dci).

Wing shape. Forewing overall sub-triangular and appearing elongated, costa approximately straight, apex roughly pointed, outer margin very slightly convex, inner margin approximately straight; hindwing overall round and slightly elongated, costa curved and naturally continues to convexed outer margin, tornus rounded and appearing somewhat produced.

Wing pattern. Dorsal forewing ground colour brown with deep-purple semi-metallic sheen; brand present as densely packed light brownish scales at base of cell Cu1 as well as in adjacent area of cell Cu2, scattered with dark brownish scales; five semi-transparent hyaline macules in cells R4, R5, M3, Cu1, and discal cell, as illustrated; dark brown long hairlike scales distributed at base of cell Cu2, with semi-iridescent viridian scales underneath, roughly mirroring range of hair-like scales, small patch of white scales present along 2A distal of area with these long hair-like scales and viridian scales; white long hair-like scales present at roughly basal ⅓ to ½ of cell 2A; Dorsal hindwing ground colour similar to dorsal forewing; two streaks of white long hair-like scales, one in discal cell (also slightly extending into cells M2 and M3 as concolorous scales), another in cell Cu2, as illustrated; Ventral forewing ground colour greyish brown, iridescent viridian scales scattered at base; semi-iridescent golden-brownish scales along costa and few other cells above discal cell, becoming less apparent distally; yellow markings present in cells R3, R4, R5, M1, and M2 (few yellow scales also visible in cell R2), as illustrated; five semi-transparent hyaline macules appearing as in dorsal surface; small patch of white scales along 2A mirroring that of dorsal surface except for appearing as larger patch; Ventral hindwing ground colour similar to ventral forewing; most area anterior of Rs yellowish, extending into distal side of cell M1, streaks of yellowish scales also visible at distal side of cells M2, M3 and Cu1; orangeish long hair-like scales and orangeish scales distributed in discal cell and extending to cell M2 and Cu1 (somewhat blending with distal yellowish scales), and to less extent in adjacent cells, as well as covering area posterior of 2A; silver marking present at base of cells M2 and M3.

Genitalia ( Figure 3 ). Tegumen somewhat trapezoidal in lateral view, less sclerotised region visible laterally and dorsally, posterior margin with flat angular projection in dorsal view, long hair-like setae along posterior margin in dorsal view (also visible in lateral view), ventral margin forming somewhat rhombus-like plate extending towards gnathos; uncus short, apical tip ending in slightly hooked point in lateral view, short hair-like setae present along ventral margin, possessing concavity in posterior margin in dorsal view; gnathos as short horn-like arms reaching posterior tip of uncus in lateral view; ventral arms of tegumen and dorsal arms of saccus appearing almost evenly broad in lateral view except for broadening near tegumen and saccus; saccus anteriorly projecting as long narrow process, similar or slightly longer than valva in length, posterior margin of saccus slightly projecting; juxta appearing as narrow sclerotised stripe with two rectangular plates on anterior margin in ventral view; valva broad, slightly narrowing distally and apical tip ending up as hooked projection in lateral view; phallus roughly straight, length similar to saccus plus valva, phallobase occupying approximately half of phallus and apparently less sclerotised compared to aedeagus, somewhat inflated, aedeagus distally dentate and terminating in hooked point, manica with two sclerotised plates with hairlike setae.

FEMALE. Unknown

Types. HOLOTYPE, male with the following labels written verbatim:// PANAMA: Bocas del Toro vic. Fortuna; Fortuna cabin; Palo Seco Forest Preserve ca. 910 m.; N08° 46’ 40.86 ‘“ W082° 11 ” 25.02’’, 31 July 2019. John R. MacDonald//LEP-DNA-68820//( MEM) . PARATYPES: three males with the following labels written verbatim:// PANAMA: Bocas del Toro vic . Fortuna; Fortuna cabin; Palo Seco Forest Preserve ca . 910 m.; N08° 46’ 40.86’’ W082° 11’ 25.02’’, 5 August 2019. John R. MacDonald//LEP-DNA-68821//( MEM);// PANAMA: Bocas del Toro vic . Fortuna; Fortuna cabin; Palo Seco Forest Preserve ca . 910 m.; N08° 46’ 40.86’’ W082° 11’ 25.02’’, 1 August 2019. John R. MacDonald//LEP-DNA -68819//Genitalic vial SN-20-35 S. Nakahara//( MEM);// COSTA RICA: Prov . Cartago Guayabo Nat. Monument, 1100 m 09°58’20’’ N, 83°41’ 25’’ W 21 .viii .2012 I . & M . Nakamura leg.// Genitalia Prep. 06- 2020-2 I. Nakamura//(ICNA).

Etymology. The specific epithet is dedicated to Ichiro Nakamura’s wife, Mitsuko Nakamura, who accompanied him on the field trip which yielded the first known specimen of this spectacular new skipper. This species name is regarded as a feminine noun in apposition.

Distribution and natural history ( Figure 5 ). Vettius mitsuko n. sp. is known to date from two localities approximately 220 km apart in Central America: Guayabo, Cartago province, Costa Rica and Fortuna cabin, Bocas del Toro province, Panama. Both sites lie at a similar altitude of around 1,000 m. At the type locality, JRM observed V. mitsuko n. sp. flying in a light gap area along a jungle trail along a sloping hillside. Of the three specimens collected, only a single individual was seen each day, which seemed to be active between 11 am-2 pm and would land on sunlit leaves of vegetation about 1–3 m off the ground. Some local members of the butterfly community include Pierella helvina incanescens Godman & Salvin, 1877 , Morpho helenor veragua Le Moult & Réal, 1962 , Eryphanis bubocula (Butler, 1872) , Nessaea aglaura (Doubleday, [1848]) , Antirrhea pterocopha Salvin & Godman, 1868 (all Nymphalidae ), and Mesosemia coelestis Godman & Salvin, 1885 (Riodinidae) . The trail where JRM collected Vettius mitsuko n. sp. is shaded and winds down from the Fortuna cabin, where Catasticta sibyllae Nakahara, Padrón & MacDonald, 2018 (Pieridae) was captured in May 2018 by the waterfall along the road that runs in front of this cabin (see Nakahara et al. 2018a). These two sites are approximately 0.16 km apart.

Figures

Figure 1. A maximum likelihood tree inferred in IQ-TREE (v.2.0.6) (LnL = -2621.466). Support values are SH-aLRT/aBayes/UFBoot; HT denotes the holotype.

Figure 2. Adult male Vettius: top row, V. mitsuko n. sp. holotype, dorsal surface on left and ventral surface on right. Bottom row, V. phyllus (from Darién, Panama; dorsal surface on left and ventral surface on right.) on right, V. charges (from Colón, Panama; dorsal surface on left and ventral surface on right.) on right. Scale bar = 1 cm.

Figure 3. Male genitalia of V. mitsuko n. sp. based on SN-20-35: a) genitalia (without phallus) in lateral view; b) external view of valva in lateral view; c) dorsal view of valva; d) phallus in ventral view; e) phallus in lateral view. Scale bar = 1 mm.

Figure 4. Comparison of Vettius species male genitalia and forewing lengths: a) saccus of V. phyllus; b) saccus of V. chagres; c) saccus of V. mitsuko n. sp.; d) left valva of V. phyllus; e) left valva of V. chagres; f) left valva of V. mitsuko n. sp.; Graph showing the male forewing lengths of three species discussed herein, number of examined specimens for each species are: V. phyllus (n = 16; mean = 18.8 mm); V. chagres (n = 10; mean = 18.25 mm); V. mitsuko n. sp. (n = 4; mean = 21.5 mm). Scale bars = 1 mm. All materials used for genitalia dissection and forewing length measurements for V. phyllus and V. chagres were from Panama.

Figure 5. a) Photo along the trail showing the general habitat where V. mitsuko n. sp. was found; b) second photo shows the view of the backyard of the Fortuna cabin with the trail beginning at the far end of the yard where it slopes steeply downhill; c) distribution map of V. mitsuko n. sp. (TL denotes its type locality).