Pachythone gagarini Dolibaina & Dias, 2024

Dolibaina, Diego Rodrigo, Dias, Fernando Maia Silva, Mielke, Olaf Hermann Hendrik & Casagrande, Mirna Martins, 2024, An overview of the Brazilian Atlantic Forest species of Pachythone Bates (Lepidoptera: Riodinidae), with the description of a new species and an updated checklist of Pachythonina, Zootaxa 5523 (1), pp. 35-48 : 36-38

Pachythone gagarini Dolibaina & Dias , sp. nov.

urn:lsid:zoobank.org:act:59A8C06D-6F6F-4BD0-A054-6B567D3075A3

( Figs 1–4 , 18–23 )

Diagnosis. Pachythone gagarini sp. nov. can be immediately distinguished from other species of Pachythone by the dorsal color and pattern of the wings, almost entirely dark brown except by thin white lines and a white area along the inner margin of the hind wing, whereas most of the hind wing underside and body are white ventrally ( Figs 1–4 ). The species superficially most similar and potentially sympatric with P. gagarini sp. nov. is P. sumare Callaghan, 1999 ( Figs 5–6 ), from which it differs by its remarkable larger size, white scaling covering a larger extension of the hind wing upper side, and by the presence of spots surrounded by a fine line of white scales in the basal area of the forewing underside.

Description. MALE. Head: Eyes brown and naked, surrounded by white and brown scales; frons predominantly brown; labial palpi short, mostly white, third segment brown; antennae about 55% the forewing length, mostly brown, with long white areas laterally, club dark brown, tip dark orange.

Body: Thorax dark brown with a thin white lateral line dorsally, white ventrally; legs white; first to third abdominal segments dark brown with posterior margin white, other segments white dorsally, entirely white ventrally.

Wing shape: Forewing length in male holotype 18,4mm; female allotype 18,8mm. Forewing costal margin nearly straight, convex near apex; apex not projected; outer margin distinctly convex; anal margin more or less straight.

Dorsal surface: Forewing dark brown; basal area with scattered white scales delimiting four roughly circular slightly darker areas, two in discal cell and two below the discal cell; discontinuous thin and white discal line, surrounding distally the two distal most circular darker areas; end of discal cell with a narrow dark brown mark; postdiscal line thick and dark brown crosses most of the wing; submarginal white line faint, more evident in CuA 2 to the anal margin. Hind wing dark brown, white below CuA 2; basal area with four rounded slightly darker spots, two in and two below the discal cell, which could be surrounded by a thin white line; postdiscal line dark brown and irregular; submarginal area with a thin white zigzagged line; outer line dark brown; fringe same as the ground color.

Ventral surface: Forewing dark brown, darker close to the apex, submarginal and outer margin; white scales concentrated at the base of the wing; basal area with four circular brown spots darker than ground color, surrounded by a fine line of white scales, two in and two below the discal cell; end of discal cell with a dark brown narrow spot surrounded basally and distally by a thin white line; postdiscal dark brown irregular line thinner than on dorsal; submarginal white line surrounds proximally a row of poorly defined rounded spots in the space between veins; tornus covered by white scales; fringe same as ground color, except by a small white spot in CuA 2 –2A. Hind wing mostly white, except basal half of costal area and above the submarginal area; basal area with five circular dark brown spots, one above, two in and two below the discal cell; postdiscal line dark brown and irregular; submarginal area with a row of dark brown ocelli in the space between veins, larger in M 1 –M 3; fringe a mix of brown and white scales, completely white in CuA 2 –2A and along the anal margin.

Genitalia: Tegumen slightly longer than uncus, rectangular in dorsal view, roughly triangular in lateral view, lower anterior most edge as a ventral rounded lobe, dorsolaterally divided from uncus by two long and narrow fenestrae; ventral projection of tegumen fused with dorsal projection of saccus, enlarged, S-shaped; saccus very short; uncus wider than long dorsally, roughly squared laterally, with a short median indentation on the distal margin; gnathos C-shaped, connected to tegumen below fenestra by a narrow area, basal half large with a short anterior projection on its lower portion, distal half narrowing to a sharp tip; valvae laterally with a large rounded basal half, suddenly narrowed into a narrow upcurved distal half; medial projection connects valvae by a short distal tip; transtilla well sclerotized, connected at the base of valva, reaches aedeagus at about its half-length, extending until the anterior margin of aedeagus; aedeagus longer than valvae, strongly curved at near 90º on its anterior half, posterior margin acute, ejaculatory bulb opens anteriorly, vesica opens dorsally, no cornutus.

FEMALE. Differs from male as follows. Wing shape: wings rounder along all margins.

Dorsal surface: Forewing white dots more marked, postdiscal band distally surrounded by a discontinuous thin white line, and with two rectangular white spots near the costal margin. Hind wing postdiscal band surrounded distally by a white line, thicker between median veins.

Ventral surface: Forewing with a larger extent of white scales, mainly after the postdiscal dark brown line.

Genitalia: Sterigma well sclerotized, as an inverted V-shaped plate, median distal margin projected and with a short indentation; antrum sclerotized as a tube with a deep ventral indentation; bursa copulatrix membranous, long; ductus bursae slender, about twice longer than corpus bursae; corpus bursae oval, with a pair of lateral signa on its upper portion, signa oval with a central keel, almost entirely open except by the very short basal portion.

Etymology. The new species is named to honor Paulo Gagarin (St. Petersburg, Russia, 1885— Rio de Janeiro, Brazil, 1980), a Russian nobleman (he liked to style himself as “Prince”) and painter settled in Brazil after the First World War, where he lived between 1921 and his death in 1980. He amassed a significant Lepidoptera collection comprising of specimens mostly from Rio de Janeiro and São Paulo states, including all specimens of P. gagarini sp. nov. known to date. About 10.000 specimens he donated from his collection to Museu Nacional do Rio do Janeiro were destroyed in the September 2th, 2018 museum fire, however, the bulk of his collection of about 25.000 specimens are currently deposited at the DZUP. The name is formed as a noun in the genitive case.

Type material. Holotype male with the following labels: / HOLOTYPUS / [ Brazil, Rio de Janeiro, Petrópolis] Independência , [900 m], 22-I-1937 [Gagarin leg.] / Ex. Col. Gagarin / DZ 31.050 / Holotypus Pachythone gagarini Dolibaina& Dias det. 2024 / deposited at the DZUP. Allotype female with the following labels: / ALLOTYPUS / Independencia 900m [,] Petropolis-E[stado]. do Rio [de Janeiro,] 24-2-1938 GAGARIN [leg.] / Ex. Col. Gagarin / DZ 31.051 / Allotypus Pachythone gagarini Dolibaina & Dias det. 2024 / deposited at the DZUP .

Paratypes (4 males and 1 female). BRAZIL — Rio de Janeiro: Petrópolis (Independência), 900m, 15-XI-1936, 1 male, Gagarin leg. (DZ 31.053) and 1 female, Gagarin leg. (DZ 31.049*), 2-III-1938 , 1 male, Gagarin leg. (DZ 31.047*), 27-IV-1938 , 1 male, Gagarin leg. (DZ 31.054), 25-VIII-1938 , 1 male, Gagarin leg. (DZ 31.052) .

Distribution and phenology. Although expected to occur in a wider geographical range, Pachythone gagarini sp. nov. is only known from its type locality, an Atlantic Forest hilltop of mid elevation known as Morro Independência, Petrópolis municipality, Rio de Janeiro state, Brazil ( Fig. 23 ). Individuals were recorded from January to April, August and November.

Comments. Pachythone gagarini sp. nov. is one of the most easily recognizable species of the genus. The wings are almost completely dark brown with white dots, anal area of the hind wing white, four brown rounded spots surrounded by a fine line of white scales at the base of the ventral forewing, in addition to its occurrence confined to the Brazilian Atlantic Forest, permits its unequivocal recognition. Interestingly, the presence of spots surrounded by a fine line of white scales on the ventral forewings of P. gagarini sp. nov. is unique in the Pachythonina , resembling those present in several genera of the Nymphidiini ( Hall 2018) , including Annulata Hall, 2018 , Catocyclotis Stichel, 1911 , Livendula Hall, 2007 , Nymphidium Fabricius, 1807 (Nymphidiina) and Zabuella Stichel, 1911 (Zabuellina).

Conservation. The type locality of P. gagarini sp. nov. is a small area impacted by human occupation in the last decades which suppressed part of the vegetation. Another poorly known riodinid currently listed as “Endangered” in the Brazilian Red List of Endangered Species, Petrocerus catiena (Hewitson, 1875) ( Freitas et al. 2018) , was also recorded in the type locality of P. gagarini sp. nov. ( Callaghan 1979). No additional specimen of P. gagarini sp. nov. has been recorded in nearly 90 years, probably because of sampling bias in the potential area of occurrence of the species. Additionally, P. gagarini sp. nov. was probably captured on a hilltop, areas considered difficult access that are neglected by most collectors.

Figures

FIGURE 23. Distribution map of the species of Pachythone endemic to the Brazilian Atlantic Forest.

FIGURES 1–6. Adults of Pachythone endemics from the Atlantic Forest of Brazil, in dorsal (left) and ventral (right) views. 1–4. P. gagarini, Dolibaina & Dias, sp. nov., 1–2, male holotype from Morro da Independência, Petrópolis, Rio de Janeiro; 3–4, female allotype, same locality as the holotype. 5–6. P. sumare, male from Joinville, Santa Catarina. All specimens are deposited at the DZUP. Scale bar: 1 cm.

Figures 18–22. Male and female genitalia of P. gagarini, Dolibaina & Dias, sp. nov. 18: lateral view of the male genitalia. 19: dorsal view of tegumen and uncus. 20: ventral view of valvae and pedicel. 21: female genitalia in ventral view and front view of the signum (indicated by the arrow). 22: lateral view of the papilla analis.