Tyloperla courtneyi, Stark & Sivec, 2005

Stark, Bill P. & Sivec, Ignac, 2005, New Species Of Tyloperla (Plecoptera: Perlidae) From Vietnam And Thailand, Illiesia 1 (1), pp. 1-7 : 1-3

Tyloperla courtneyi , sp. n. ( Figs. 1 -6,21-23)

Material. Holotype ♂ and 1 ♀ paratype from Thailand, Chiang Mai, Doi Inthanon National Park, Siriphum waterfall, 8-9 May 2002, Chiang Mai University Team ( PMSL).

Adult habitus. Triocellate. Head yellowish with dark brown spot between ocelli expanded along anterior margin near callosities; anterior region of frons dusky brown forward of M-line; pronotum brown with darker rugosities ( Fig. 1 ). Palpi, antennae and cerci brown. Legs brown with distal end of femora and proximal end of tibiae slightly darker. Wing membrane and veins brown.

Male. Forewing length 17 mm. Hairbrushes reduced on abdominal sternum 5 but well developed on sterna 6-7 and on thoracic metasternum. Tergum 8 and 9 without distinct lobes but each with a mesal low mound covered with sensilla basiconica ( Fig. 2 ). Basal cushion of hemitergal process about 1/3 of inner length of process; process rounded dorsally, grooved along inner surface and pointed dorsoapically ( Fig. 3 ). Aedeagal sac apically recurved and bearing a pair of small basolateral, spiny lobes ( Fig. 4 ); sac apex offset by a distinct subapical constriction; armature well developed as a broad patch of small spines over apex and extending beyond subapical constriction over lateral and ventral surfaces to near midlength of sac. Cercal segments with a single enlarged ventral bristle.

5

Female. Forewing length 24 mm. Subgenital plate arcuate with a median U-shaped notch extending deeply into plate; plate produced over ca. ¼ or less of sternum 9 ( Fig. 5 ). Vagina about as wide as long with major anterior chamber weakly lined along lateral wrinkles with brown setae. Spermatheca hook shaped ( Fig. 6 ).

Egg. Length ca. 0.42 mm, width ca. 0.38 mm. Collar short, ca. 0.03 mm in length, and wide, ca. 0.20 mm in diameter ( Fig. 22 ); collar rim smooth and slightly flanged, sides with a series of obscure vertical ridges ( Fig. 21 ). Chorion covered with irregularly shaped large pits with ornately punctate floors. Opercular ring distinct as a narrow groove separating lid from egg body ( Fig. 23 ). Micropyles not observed.

Larva. Unknown.

Diagnosis. Males of this species are similar to those of T. formosana (Okamoto) and T. khang (described below) in external genitalic features. It differs from the former in having shorter, more rounded hemitergal calluses and in lacking small subapical lobes on the aedeagal sac. Tyloperla khang lacks lateral lobes on the aedeagal sac but a pair of these are present basolaterally in T. courtneyi .

Etymology. The patronym honors G. Courtney for his leadership in the study of Thai aquatic insects.

Figures

Figs. 1-6. Tyloperla courtneyi. 1. Head and pronotum. 2. Male terminalia. 3. Hemitergal process, dorsolateral. 4. Aedeagus, lateral. 5. Female terminalia. 6. Vagina and spermatheca.

Figs. 21-23. Tyloperla courtneyi egg structures. 21. Entire egg, lateral. 22. Egg collar, polar aspect. 23. Opercular ring and lid.