Perigomphus basicornis, Amaya-Vallejo & Novelo-Gutiérrez & Realpe, 2017

Amaya-Vallejo, Vanessa, Novelo-Gutiérrez, Rodolfo & Realpe, Emilio, 2017, Perigomphus basicornis sp. nov. (Odonata: Gomphidae) from Anchicayá, Colombia, Zootaxa 4294 (3), pp. 395-400 : 396-398

Perigomphus basicornis sp. nov.

( Figs 1–7 )

Holotype. ♂ ( IEXA), Colombia, Alban Alto Anchicayá, Buenaventura, Valle del Cauca, La Loquita stream (3° 34' 38.5"N, 76° 52' 50.8"W; 630 m a.s.l.), 9.ix. 2016 as mature larvae, reared in lab (LAZOEA-UNIANDES); emerged 22.xi.2016. V. Amaya-Vallejo leg.

Paratype. One ♂ ( IEXA), same data as the holotype; emerged on: 24.iii.2017. Deposited in Colección Entomológica del Instituto de Ecología, A. C., Xalapa, Veracruz, México ( IEXA).

Etymology. The name basicornis refers to the ventral, sub-basal horn-shaped projection of cerci.

Description of the holotype. Head. ( Fig. 1 ). Eyes in life dark brown, with pale yellow borders; labium cream colored, dark brown medially, with long pale setae; labrum pale yellow on distal half, brown on basal half; anteclypeus and postclypeus dark brown, postclypeus with three pale yellow spots, one on each side and one on the middle; frons dark brown with a large, transversal, dorsal pale spot on each side of midline, not contiguous; vertex, occiput and rear of head dark brown, anterior surface of vertex lustrous, postero-dorsal surface of vertex and occiput dull; numerous long, dark brown setae on face and dorsum of head; occiput slightly concave, dark brown with long brown setae along entire width; antenna dark brown.

Thorax. Anterior and middle lobes of prothorax mostly light brown, pale yellow at sides. Synthorax ( Fig. 1 ) with mid-dorsal carina brown, mesepisternum brown with two pale stripes, one dorsal and connected to pale collar anteriorly, not reaching the antealar crest posteriorly, the second one running parallel to humeral suture but only on distal 0.55 of the length of mesepisternum, widened at distal end; mesepimeron brown with a wide pale stripe fulllength; metepisternum and metepimeron mostly pale with a brown stripe on metapleural suture, venter of pterothorax pale yellow. Coxae grayish yellow, prothoracic and mesothoracic femora mostly dark brown, metathoracic femur pale yellow ( Fig. 1 ), tibiae light to dark brown, tarsi and 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, with a slight yellow basal wash. Venation dark brown; width of hind wing 1/3 its length. Second primary antenodal crossvein 6th in FW, 5th in HW. Antenodal crossveins: FW 13; HW 8. Postnodal crossveins: FW 10 (left), 11 (right); HW 9 (left), 9 (right). Pterostigma gray, covering about 3.2 cells in FW, 3.75 cells in HW.

Abdomen. S1–7 very slender widening at S8 from 1.2 mm at base to 1.6 mm posteriorly, S9 about 1.8, S10 about 2.0 mm wide, making the abdomen to appear wedge-shaped. S1 pale yellow, S2 dark brown on dorsum except for a narrow pale yellow mid-dorsal stripe; S3–7 blackish brown with narrow pale yellow mid-dorsal stripe and shorter latero-basal yellow triangle; S8–10 blackish brown except S8 with very small latero-basal yellow spot. Anterior hamule ( Fig. 2 ) with apex deeply excavated medially, the external branch large, flattened, with posteroventral margin straight, the internal branch shorter, hook-like; posterior hamule directed ventro-apically, exposed portion about 1.0 mm long, apex notched before tapering to hook-like point ( Fig. 2 ). Vesica spermalis as shown in Fig. 3 , with a blunt superior tooth on third segment tip with two short flagella, tip of penis guard evenly convex and without median excision. Cerci pale yellow (almost white), in dorsal view ( Fig. 4 ) wide at base, dark medial angle of each cercus rounded and far from that of the opposite; lateral margin with a basal, large peciolated lobe with three conspicuous teeth on distal margin ( Figs. 4, 5 ); long apical portion of cerci slender and slightly curved at tip, mesal margin strongly carinate ending in a rounded point ( Figs. 4, 5 ); cerci in lateral view ( Fig. 6 ) straight with a conspicuous sub- basal, ventral horn-shaped projection; short bristles along entire length. Epiproct dark brown, widely divaricate ( Fig. 7 ), half the length of cerci. Apices in dorsal view extending laterally beyond margins of cerci ( Fig. 4 ), in lateral view with a strongly recurved tip ( Figs. 5, 6 ). Paraproct dark brown, with a finger-like, dorso-lateral projection ( Figs. 5, 6 ).

Measurements (mm). TL 35.0, AL 26.1, FWL 23.8, HWL 22.0, HWW at nodus 7.8, FW ptL 3.9, HW ptL 4.0, head W 6.1, HfL 4.0, cerci L 1.70.

Variations in paratypes. Additional male shares most of the described characters for the holotype, with slight variations in measurements (mm): TL 34.0, AL 25.5, FWL 23.6, HWL 22.0, HWW at nodus 7.7, FW ptL 3.7, HW ptL 4.0, head W 6.0, HfL 4.1, cerci L 1.68.

Differential diagnosis. The new species could be distinguished by the strong sub-basal ventral horn and the absence of subapical notches in the mesal carinate margin of cerci. Distance of extreme base of cerci is subequal to the distance of the tips.

Habitat and Ecology. The larvae of P. basicornis were found in a small seasonal forest creek, with the water flow increased by the rains. The fast-flowing creek was about 50 cm wide and 7 cm depth at its deepest point. They preferred microhabitats with a bottom of pebbles, small rocks and coarse sand, pieces of fallen leaves, thick riparian vegetation and high dissolved oxygen concentrations (9.5 mg /L average) ( Amaya-Vallejo 2009).

Figures

FIGURES 1 – 3. Perigomphus basicornis sp. nov., holotype ♂. 1) Head, thorax and partial view of wings and abdomen. 2) Details of accessory genitalia; ventro-lateral view of genital fossa, showing anterior hamuli and the right posterior hamulus reclined to opposite side. 3) Vesica spermalis, right lateral view.

FIGURES 4 – 7. Perigomphus basicornis sp. nov., holotype ♂. 4) Dorsal view of S 9 – 10 showing the caudal appendages. 5) Left latero-dorsal view of caudal appendages. 6) Left lateral view (slightly ventral) of caudal appendages. 7) S 8 – 10 and caudal appendages, ventral view. a = arm of epiproct, Ah = anterior hamuli, Ce = cerci, Ep = epiproct, p = baso-lateral process of cerci, Ph = posterior hamulus. Pr = dorsolateral process of paraproct, sbvh = sub-basal ventral horn of cerci.