Perigomphus angularis, Tennessen, 2011

Tennessen, K. J., 2011, Perigomphus angularis spec. nov. from central Ecuador (Odonata: Gomphidae), Zootaxa 2915 (1), pp. 66-68 : 67

Perigomphus angularis sp. nov.

( Figs 1–4 )

Etymology. The name angularis refers to the basal, dorso-medial angle of the cerci.

Specimens examined. One ♂, ECUADOR, Morona Santiago Province, small stream 1 km S of Río Pasanac bridge, Hwy. 45 (1° 57' 0.4"S, 077° 51' 46.8"W; elev. 820 m), 16 Sept. 2005, K. J. Tennessen leg. ( FSCA) .

Holotype. Head: Eyes in life dark brown; labium gray brown, darker medially, tan marginally, with long pale setae; labrum gray, distal margin black; anteclypeus black, postclypeus gray anteriorly, dark brown medially; frons blackish brown; vertex, occiput and rear of head dark brown; numerous long, black setae on face and dorsum of head; occiput rounded, blackish brown with long black setae along entire width; scape dark brown to black, rest of antenna black.

Thorax: Anterior lobe of pronotum gray, middle and posterior lobes brown. Pterothorax similar to that of P. pallidistylus ( Belle 1972, p. 280, Fig. B); middorsal carina brown, middorsal (mesepisternal) brown stripe widened in basal half, 1.35 mm wide at widest point, slightly tapering distally to width of 0.89 mm; adjacent pale mesepisternal stripe olive green, connected anteriorly to pale collar, narrowing distally and ending 0.5 mm before antealar crest ( Fig. 1 ); olive green stripe above mesopleural suture isolated, slightly less than 0.2 mm wide at mid-length, widened at distal end ( Fig. 1 ); metepisternum mostly brown but with an isolated olive green stripe 0.4 mm wide at mid-length, widened distally and with a small dorsally directed arm; metapleural suture with isolated diffuse brown stripe, metepimeron olive green, venter of pterothorax gray tan. Coxae gray brown, femora mostly dark brown, tibiae darker brown to black, tarsi black, pretarsal claws blackish brown with distinct supplementary tooth; femur spines black, distal spines about as long as space between bases of adjacent spines and about 0.8 times width of femur. Wings clear, venation black; width of hind wing 1/3 its length. Second primary antenodal crossvein 6 th in Fw, 5 th in Hw. Antenodal crossveins: Fw 12; Hw 8. Postnodal crossveins: Fw 8 (left), 9 (right); Hw 8 (left), 9 (right). Pterostigma dark brown, enclosing veins black, about 1/7 HwL, covering about 3.66 cells in Fw, 3.75 cells in Hw.

Abdomen: S1–10 mostly dark brown, slender at mid-length (S4–S7 about 0.8 mm wide in dorsal view), widening at S8 from 1.0 mm at base to 1.6 mm posteriorly, S9 about 1.7, S10 about 1.9 mm wide. S1 olive green laterally, brown dorsally, S2 similar, dark brown on dorsum except for narrow yellow mid-dorsal stripe; S3–S7 blackish brown with narrow yellow mid-dorsal stripe in basal half and shorter latero-basal yellow triangle; S8–S10 blackish brown except S8 with very small latero-basal elongate yellow spot. Anterior hamule small, mostly hidden within genital fossa, apex excavated with very small medial projection and numerous light brown setae ( Fig. 2 inset); posterior hamule directed ventro-apically, exposed portion about 0.8 mm long, apex with slight notch before tapering to hook-like point ( Fig. 2 ). Vesica spermalis similar to that of P. pallidistylus ( Belle 1972, p. 280) except 3 rd segment and blunt lobe relatively shorter ( Fig. 2 ). Cercus mostly pale yellow, in dorsal view wide at base, dark medial angle projecting toward midline and almost meeting that of opposite cercus; lateral margin with a basal, laterally projecting lobe; long apical portion slender and straight, mesal margin carinate, with small subapical notch ( Fig. 3 ); cercus in lateral view straight, with slight basoventral projection ( Fig. 4 ); short hair-like setae along entire length. Epiproct dark brown, widely divaricate, length slightly less than length of cerci, apices in dorsal view extending laterally beyond margins of cerci, in lateral view with sharp hook-like recurved tip ( Fig. 4 ). Paraproct black, bulbous, with dorso-lateral projection ( Figs. 3–4 ; projection on left side clearly visible in Fig. 3 but hidden on right side due to slight twist at apex of abdomen during preservation).

Measurements (mm), holotype. TL 36.0, AL 27.3 mm, FwL 23.2, HwL 22.0, HwW at nodus 7.4, Fw PtL 2.75, Hw PtL 2.95, head W 5.3, HfL 4.6, cercus L 1.60.

Female unknown.

Diagnosis. Males of the two known species of Perigomphus are similar in thoracic color pattern, but they are clearly distinct based on four male characters: 1) pallidistylus has about 30 stout black denticles on the dorsal rim of S10 whereas angularis has none, 2) the cerci of pallidistylus in lateral view have a distinct sub-basal ventral projection which is vestigial in angularis , 3) the mesal margin at the extreme base of the cercus is undeveloped and slightly undulate in pallidistylus vs. produced inward as an angular projection in angularis ( Fig. 3 ), and 4) the epiproct is about one-fourth to one-third the length of the cerci in pallidistylus but nearly half the length of the cerci in angularis . In addition, the second primary antenodal crossvein is the 6 th crossvein in the fore wing and the 5 th in hind wing in angularis (7 th and 6 th in pallidistylus ), and the cercus of angularis has a basal, laterally projecting wide lobe ( Figs. 3–4 , labeled p) which Belle (1972) did not figure or mention in his description of pallidistylus .

Biological notes. The small, slow-flowing stream where the holotype of P. angularis was found is on the eastern slopes of the Andes Mountains at 820 masl, and was about 1 to 2 m wide and about 25 cm at its deepest point. Substrate was silt, sand, and rock. The male was perched in a sunny spot amid small trees, on the tip of a twig about 1 m above ground, in the early afternoon. Other species of Odonata observed at the same locality included Epigomphus obtusus Selys , Micrathyria sp. , Orthemis cultriformis Calvert , Hetaerina sanguinea Selys , Polythore derivata McLachlan , Argia sp. , and Telebasis carota Kennedy.

Figures

FIGURES 1–4. Perigomphus angularis sp. nov., male holotype. 1) Pterothorax, left lateral view. 2) Accessory genitalia, right lateral view, inset = apex of right anterior hamule. 3) S10 and anal appendages, dorsal view. 4) S10, right cercus, paraproct and epiproct, right lateral view; Pr = dorso-lateral process of paraproct, p = baso-lateral process of cercus, a = arm of epiproct.