Walkeriella, Mielke & Grehan & Grados, 2019

Mielke, Carlos G. C., Grehan, John R. & Grados, Juan, 2019, Description of Walkeriella miraculosa, gen. n. et sp. n. from South-East Peru (Lepidoptera: Hepialoidea: Hepialidae), Zootaxa 4609 (2), pp. 335-342 : 336-337

Walkeriella gen. nov.

Type species: Walkeriella miraculosa sp. nov., monotypic by present designation.

Diagnosis. Externally distinguished from all other Pan-American Hepialidae by a large white spot edged with dark brown at the base of each discal cell and by the large curved spot between Rs1 and M 1 at the outer anterior discal cell. Walkeriella gen. n. is also recognized by the distinctive male genitalia, particularly the valva with its concave inner (medial) surface extending from the base to the apex in contrast to either a blade-like shape or lobular shape in the other American species, and by the ‘oxycanine’ venation on the forewing and ‘hepialine’ venation ( Dumbleton 1966) on the hindwing with partial fusion of Rs1+Rs2 and Rs3 at their base.

Description. Male ( Figs 2–9 ). Head. Clypeus anteriorly glabrous and mesally projected, differentiated from the frons. Labial palpus with one tiny, rounded palpomere. Antenna lamellate.

Thorax. Legs: Distitarsus without arolium. Fore- and hindwings: venation typical for cibyrine genera with Sc and R aligned very close together over much of the distal wing ( Grehan & Rawlins 2018). Forewing with Sc1 and hindwing with vestigial (barely visible) Sc1 ( Fig. 4 ).

Abdomen ( Figs 6–8 ). Well sclerotized, tuberculate plates distinct; tergum I with lateral ridge meeting anteriolateral tuberculate plate; anterior margin with weakly sclerotized ridge, not fused to dorsal tergal brace of tergosternal connection. Tergosternal connection with short dorsal and lateral brace curving together next to broad, triangular intermediate zone with prominent posterior-ventral tergal knob; upper anterior margin with small space or lacuna ( Fig. 6 ).

Male genitalia ( Fig. 9 ). Tegumen indistinct, likely fused to the pseudotegumen, ventral portion articulated with saccus. Saccus U-shaped anteriorly; posterior edge W-shaped with lateral expansions on either side, with indentation mesally. Tergal lobes forming narrow arch meeting anterior margin of pseudotegumen. Pseudotegumen compound of two conspicuous C-shaped lateral plates fused together on their anterior-ventral margins; its dorsal projection asymmetrical, ventral projection symmetrical with strongly sclerotized apex. Fultura inferior trapezoidal. Fultura superior comprising two reduced and narrow sclerotized longitudinal bands, one on either side. Valvae slightly curved, tapered and lightly setose. Phallus membranous.

Female. Unknown.

Etymology. This new genus is named for Francis Walker, a British entomologist, who described some Neotropical Hepialidae species in the 19 th century. The name follows the tradition of Druceiella , Dugdaleiella Grehan & C. Mielke , Hampsoniella , Kozloviella Grehan & C. Mielke , and Pfitzneriella Viette. The gender of the name is feminine.

Remarks. The presence of Walkeriella gen. n. in southern Peru, a relatively well surveyed country, is surprising since no other similar taxon is so far known from the Neotropical region. The presence of a strongly developed posterior lateral knob, a broad intermediate connection between the tergosternal bar and the lateral ridge and a broken anterior margin at the tergosternal connection, along with a very close parallel position between the outer hindwing Sc and R veins support inclusion of Walkeriella gen. n. within the ‘cibyrine’ cluster of genera ( Grehan 2012). The configuration of Rs1+Rs2 and Rs3 is unique among all Hepialidae genera and this is the first case that both hepialine and oxycanine venations are found in the same species. In the holotype the left forewing has an oxycanine arrangement (Rs3 joining the common stalk of Rs1+Rs2) whereas the right wing has a hepialine arrangement with Rs3 joining the base of Rs4. The hindwing arrangement is hepialine on both sides. The paratype has oxycanine venation on both forewings and hepialine venation on both hindwings. Further investigation will be necessary for a better understanding of this pattern.

Figures

FIGURES 2−4. Walkeriella miraculosa sp. nov., male holotype habitus. 2, Dorsal view (a), ventral view (b). Scale bar = 1 cm. 3, Forewing ornamentation (adc = anterior discal cell, cdc = central discal cell, mb = marginal band, pdb = postdiscal band, pdc = posterior discal cell, pmb = premarginal band, smb = submarginal band). 4, Wing venation.Arrow indicates the fusion of Rs1 + Rs2 and Rs3.

FIGURES 5−9. Walkeriella miraculosa sp. nov., male holotype morphological features. 5, Legs. Scale bar = 0.5 cm. 6, Tergosternal connection (ab = anterior break, db = dorsal brace, iz = intermediate zone, lb = lateral brace, SII = sternum II, TII = tergum II, tb = tergosternal bar, tl = tergal lobe). 7, Abdomen upper dorsal, lower ventral view. Scale bar = 0.5 mm. 8, Tergum (left) and sternum (right) VII and VIII. Arrow indicates the projections of tergite VII. Scale bar = 0.5 mm. 9, Genitalia: lateral view (9a), ventral view (9b; arrows indicates the fultura superior), anterior view (9c), phallus everted (9d). Scale bar = 0.5 mm.