A NEW SPECIES OF ISSIKIELLA FROM THE AMAZON BASIN (Mecoptera: Bittacidae)

A new species of Issikiella is described from southern Pará State, Brazil, and compa red with the other two known species.


INTRODUCTION
The genus Issikiella was described by Byers (1972) to include a species, Issikiella pulchra, from southern Brazil and another (undescribed) from southern Bolivia. Penny and Arias (1982) described one further species from central Amazonia and recorded one further locality for the genus, Belém, near the mouth of the Amazon. During a recent collecting trip to the middle Rio Araguaia, a further new species was collected near Conceição do Araguaia, approximately 750 km south of Belém in southern Pará State. Thus, the present distributional data indicate that the genus issikiella has a broad range encompassing most tropical and subtropical forests of South America, south of Venezuela and east of the Andes. Original description based on 13 males, 16 females, pinned.
Head: Clypeus, vertex and occiput pale brown; rostrum and ocellar triangle dark brown. Rostrum slender, labrum about five times as long as its width at base; maxillary and labial plaps dark brown, darker than other rostral elements. First segment of maxillary palp with long sensory hair. Terminal (fifth) segment of maxillary palp about same length as fourth. Eyes brown, separated in front by distance about equal to width of base of labrum, and width of ocellar triangle. Antennae short (about 3.0 mm in both sexes), very slender, each comprising elongate scape and ovoid pedicel and apparently 18 thin, cylindrical flagellomeres (segmentation obscure beyond 10th flagellomere); hairs on apical segments about four times as long as diameter of flagellomeres.
Thorax: Notal and pleural areas pale brown, becoming yellowish-brown near legs; generally glabrous, with almost no pilosity. Femora and tibiae yellowishbrown with a few scattered black spines; femora darkened at apices; tibiae only slightly darkened at tips, basitarsi dark yellowish brown grading into brown on more distal tarsomeres. Hind femur not enlarged, of more or less uniform diameter throughout in both sexes. Hind tarsus not conspicuously enlarged in male.
Wings; highly iridescent, clear dark yellow from base to origin of M and in cells. C and Sc to stigma, veins dark brown; stigma intense dark brown, large, extending from anterior wing margin to vein F)2 + 3, color continuing on crossveins and at apex of branches of R and M, beyond last crossvein; additional spots of brown at origin of Rs, first fork of Rs, origin of M, end of Cu2, in cells R and M, around both thyridia and along proximal crossveins. Subcosta extending well beyond origin of Rs (ORs), joining C just before level of first fork of Rs; Scv just beyond ORs. Vein R2 + 3 no* deflected backward at Rev. In front wing, vein 1A extends slightly beyond level of humeral crossvein (h), 2A ends just before level of h; apical crossvein present near end of 1 A, another near end of 2A; vein 3A not present. In hind wing, 1A coalesces with Cu2 for most of its length, turning to posterior wing margin as crossvein beyond level of h. Vein 2A very small, difficult to distinguish. Only one pterostigmal crossvein, near proximal end of stigma, joining R2 + 3 just beyond first cell R3.
Abdomen of Male: Segments 2 through 8 dark brown dorsally, yellowish brown ventrally; segments 7 and 8 much darker dorsally than preceding segments. Fused basistyles dark brown; epiandrial lobes translucent yellow. Epiandrial lobes elongate, with apex obtusely rounded at caudo-dorsal margin (Fig. 1); a mesally directed spiniferous point on dorsal margin approximately two-thirds distance to tip (Fig. 2) wider than long; a mesally directed, subapical, setiferous projection on ventral margin apically rounded, with small lobe at anterior base; numerous small, black denticles along mid-dorsal margin. Basistyles fused along entire length, without median membranous area. Dististyles relatively large, mesally-directed. Proctiger with a simple dorsal plate. Cerci slender, elongate, extending well beyond apex of basistyles. Aedeagus slender, only slightly enlarged at base, apparently only once coiled.
Abdomen of Female: Segments 2 to 8 uniformly dark brown, slightly enlarged posteriorly. Anterior margin of 9th and 10th terga forming more heavily sclerotized crescentic marks. Ninth sternum bearing membranous indentation, with heavily sclerotized and pigmented spot at apex (Fig. 3). Cerci quite long and slender, gradually tapering to point.
Types: Holotype male, allotype female and 27 paratypes collected at Morro da EMBRATEL, 7 km west of Conceição do Araguaia, 19-1-4-11-1983, N. D. Penny, J. A. Rafael, A.Y. Harada, J.E.B. Brasil, and R.N Habitat: This species was fairly abundant at the base of a low, forested moutain, near Conceição do Araguaia. This is one of the few areas in the region which has retained its original forest ve-getation. However, on the lower slopes there was some indication that the area had occasionally been burned, thus creating a great deal of low, herbaceous vegetation, mostly ferns. Issikiella araguaiensis was collected in association with one female Pazius (Mecoptera: Bittacidae).
Species Relationships: Of the two other known species of Issikiella, I. araguaiensis is much more closely related to I. byersi than to I. pulchra. The male epiandrium of both I. aragualensis and I. byersi has dorsal and ventral marginal projections, while I. pulchra has a central projection. Additionally, the male cerci are long in I. araguaiensis and I. byersi, while being quite short in I. pulchra. This new species can be separated from I. byersi by the shorter dorsal projection and more elongate ventral projection of the epiandrial lobes, the simpler proctiger, shorter aedeagus, and in females the distinctive spot on the ninth sternum.