Simplicivalva, Davis & Gentili-Poole & Mitter, 2008

Davis, Steve R., Gentili-Poole, Patricia & Mitter, Charles, 2008, A revision of the Cossulinae of Costa Rica and cladistic analysis of the world species (Lepidoptera: Cossidae), Zoological Journal of the Linnean Society 154 (2), pp. 222-277 : 257

SIMPLICIVALVA GEN. NOV.

Type species: Arbela philobia Druce (1898) (by present designation).

Description

Male: Forewing length: 13–20 mm.

Female: Forewing length: 14–21 mm.

Head: Antenna with inner serrate rami reduced in size; scales on antennal shaft mostly cream, with some pale brown; labial palpus cream to light brown ventrally, and mostly light to dark brown dorsally, sometimes nearly fuscous; frons creamy white, cream and pale brown to dark brown and grey-brown, and often irrorated with brown or fuscous; vertex same as frons.

Thorax: Forewing often with a terminal patch or patterned area, such as spots, at distal area adjacent to termen. Wing venation slightly variable; R 2 of forewing most often fused and forked with R 3, sometimes separate; R 3 or R 2+3 of forewing always separate from R 4; R 4 of forewing always separate from R 5.

Abdomen: Typically cream to light brown dorsally and ventrally; occasionally light to dark brown or greyish dark brown.

Male genitalia: Valva oblong and rounded terminally, with terminal end slightly upcurved, and occasionally shortened and truncate; saccular process often reduced to a small sclerotized ridge, but can be spiniform, with spine-like projection variable in size, length and number of spines; spines are usually small and curved, and arise near the base of the valva, slightly above the sacculus; valva area between sacculus and costa sometimes with modifications, such as small spines; base of costa with basal lobe variable, most often reduced and not pronounced; occasionally pronounced and projecting at an angle or pronounced but flattened and not projecting at an angle. Uncus variable, mostly simple, but sometimes shallowly bifid; elongate and fairly slender, often protruding beyond valvae, although not always; setae sparsely located along uncus. Invagination between tergite 9 of genital capsule and uncus most often curving around base of gnathos. Gnathos bridge mostly elongate, slender, and with a ridge along the midline, but sometimes flattened and without a ridge; arms fairly long and slender, typically not protruding beyond bridge, but can be bilobed, and not recurving into tergite 9. Anal tube mostly membranous, but can be lightly sclerotized. Juxta process variable, typically short, mostly fused to valva, and membranous, although can be elongate and free from valva; aedoeagus with dorsal crest variable, normally present, reduced in size, but can be absent or developed and prominent; coecum mostly developed and curved upward; rostellum digitiform and slender, with apex acute or subacute and rounded; vesica with spines sometimes absent, and when present, spines minute and setiform.

Female genitalia: Sternite 8 developed and triangular, with sides slightly concave. Intersegmental membrane between abdominal sternites 7 and 8 developed, often partially covering sternite 8 and forming a hood from which ostium opens underneath. Ductus bursae variable, from elongate to short. Corpus bursae variable, from large and oblong when ductus is shortened, to small, oblong and ovoid when ductus is elongate.

Etymology: Derived from the Latin ‘simplex’ meaning ‘simplicity’. Simplicivalva refers to the simple form of the valvae in the male genitalia, in which the saccular process is reduced to a weak ridge or is completely absent.

Discussion: Because the wing patterns within Simplicivalva appear so variable, the male genitalia offer the best diagnoses for the genus. In particular, the valvae are characteristic in being relatively large and oblong with upturned apices; the sacculus usually lacks a process but may possess other modifications such as a sclerotized ridge, a basal spine, or a basal patch of spines; the gnathos is usually long and slender, with a prominent ridge along the midline and an apical lobe which occasionally is bilobed. From the few females available for examination, it appears that the female genitalia exhibit no significant characters for generic diagnosis.