Compsoneuria perakensis Braasch and Boonsoong

Braasch, Dietrich & Boonsoong, Boonsatien, 2010, A contribution to the Heptageniidae (Insecta, Ephemeroptera) of Thailand and Malaysia, Zootaxa 2610, pp. 1-26 : 11-13

Compsoneuria perakensis Braasch and Boonsoong sp. nov.

Description. Male: Body length 5.85 mm (second male 5.26 mm); forewing 5.5 mm, hind wing 1.34 mm; caudal filaments lost.

Head: Compound eyes contiguous, dark, natural colour not conserved (Fig. 46).

Thorax: General colour of prothorax yellow brown. Forewings (Fig. 47) have cross veins brown shaded in costal and subcostal fields and crowded cross veins beneath second and third cross vein in C and SC fields; bulla region is expressed by a brown blotch. Most other cross veins and all longitudinal veins are faintly brown or even colourless; first strong cross veins are dark brown. Hind wing (Fig. 48) is almost without any tinction; only 2 cross veins in subcostal field are brown shaded. Hind leg (Fig. 49): femora length 1.8 mm, tibiae length 1.65 mm, tarsi length 1.06 mm; lengths of tarsal segments in descending order: 1=2>5>3>4. Cross bars in femur are indicated by black streaks, moreover, the face of dorsal femur is speckled; tibia with 3 cross bars, ends of tarsal segments darkened.

Abdomen: Dorsally smoky brown, terga III–VIII, with a long median darker tapered streak, sometimes slighty cleft; only in tergum V not distinctly expressed; sterna clouded, smoky brown. Sides of abdominal segments similar to that of tergum VII with a rather indistinct darker mark (Fig. 50). Penis (Figs. 51–52): somewhat slender with conspicuously tapered stem and without hook or spines. Forceps segments with length of 0.07, 0.31, 0.07 and 0.09 mm, styliger sockets low, rim at sides little elevated; styliger and first forceps segment brown, other 3 segments colourless.

Etymology: The specific name refers to the collection site Perak in northern Malaysia. At the same time S. Perak (Sungai = river) is a synonym for S. Belum (Belum River).

PLATE VII. FIGURES 46–52. Imagos of Compsoneuria perakensis sp. nov. 46, Male head, dorsal view. 47, Male forewing. 48, Male hindwing. 49, Male foreleg. 50, Male, abdominal tergum, color pattern. 51, Male genitalia, ventral view. 52, Penis, dorsal view.

Diagnosis: This new species from Malaysia represents a species of Compsoneuria with a copulatory organ of a tapered penis stem, not being as stocky as in other species from Southeast Asia, of which the whole penis stem is almost evenly broad, for example in Compsoneuria diehli , C. flowersi ( Braasch & Soldán 1986 c, b), C. spectabilis Eaton, 1881 or C. thienemanni . Further, C. perakensis has no hook at inner contour of penis lobes apically as the four prior species. African species of Compsoneuria ( Demoulin 1956; Kimmins 1937; own material) represent that more slender penis type. The adults of Compsoneuria langensis and C. lieftincki have brown-shaded hind wings. Male of Philippine Compsoneuria palawanensis Braasch and Freitag, 2008 has, so far known, unique titillators, conspicuously cleft basally.

Material examined: HOLOTYPE: male, North Malaysia, Hulu, Province Perak, Belum Expedition, B. Camp 5°30’07’’ N, 101°26’21’’ E, headwaters of S. Belum River, 250 m above sea level, VIII–XII.1993; leg. Rothamsted, at light; PARATYPE: 1 male, same locality, same time.

Types deposition: HOLOTYPE: male ( MNHU); PARATYPE: 1 male ( ZMKU); all preserved in 80 % alcohol.