Epigomphus crepidus Kennedy

Novelo-Gutiérrez, Rodolfo, Gómez-Anaya, José Antonio & Smith-Gómez, Sergio Alejandro, 2015, Description of the larva of Epigomphus crepidus Kennedy, 1936 (Odonata: Gomphidae), Zootaxa 4027 (4), pp. 587-592 : 588-591

Epigomphus crepidus Kennedy

(Figs. 1–8)

Material. Two exuviae (♂, reared), 1 F—1 larva (♀). MEXICO: Jalisco; Municipality of San Sebastián del Oeste, stream at Km 52+800, road S.Sebastián-Puerto Vallarta, reach Potrero de Arriba-Palmillas de Macedo (20° 49.015 N; 104° 58.811 W, elevation 481m asl, stream in moderately disturbed tropical dry forest), 16 March 2014 (1♂ F—0 larva, reared and emerged on 14 May 2014, 13:30 h); same data but stream at Km 57 road S.Sebastián-Puerto Vallarta, Ejido Soyatán (20° 49.899 N; 105° 0 0.649 W, elevation 439m asl), (1♀ F—1 larva); Municipality of Cabo Corrientes, Sierra Paraíso, stream La Ciénega (20° 22.840 N; 105° 19.664 W, 635m asl, stream in a forest of the endemic Pinus jaliscana Pérez de la Rosa), 18 March 2014 (1♂ F—0 larva, reared and emerged on 16 May 2014, 16:05 h), all J.A. Gómez, S.A. Smith, R. Novelo leg. All specimens deposited in Colección Entomológica del Instituto de Ecología, A.C., Xalapa ( IEXA).

Description. Medium-size exuviae (23.7–25.0 mm total length), body robust, antennae, legs and sides of thorax setose, gently tapering caudad, body light yellow-brown lacking any particular pattern (Fig. 1a), F—1 larva light yellow with a complex color pattern on abdomen (Fig. 1b).

Head: Wider than long, but narrower than thorax and abdomen. Labrum 0.7 mm long, mostly bare, anterior border with dense brush of golden setae, flattened ventrally; anteclypeus bare, postclypeus, frons, vertex and occiput with minute, moderately abundant scale-like setae, a tuft of long, upturned, golden setae on frontolateral margins of frons (between antenna and anterior margin of compound eye), occiput mostly bare, with long, golden setae on occipital lobes, anterior margin of frons concave. Antennae 4-segmented (Fig. 2), covered with minute, scale-like setae dorsally, and dense rows of long, yellowish setae on lateral margins, those on external margins longest, those on internal margins stiff, scape globose, pedicel subglobose, 3rd antennomere largest, spindle-shaped, flattened dorsoventrally, twice as long as widest part, 4th antennomere a small sphere; scape, pedicel and 3rd antennomere yellow-brown, 4th antennomere reddish brown, size proportions: 0.26, 0.20, 1.0, 0.08. Compound eyes moderately developed; ocelli pale. Occipital lobes rounded, bulging; a well-developed longitudinal carina beset with small, stiff setae to each side of ventral surface of head. Mandibles (Fig. 3) with molar crest, formula: L 1234 0 a(m1-4)b / R 1234 y a(m1-3)b, in both mandibles tooth a>b. Maxillae: Galeolacinia (Fig. 4) with 7 moderately incurved teeth, three dorsal teeth more or less of same length and robustness, four ventral teeth of different size, apical one largest; maxillary palp thick and robust. Ventral pad of hypopharynx pentagonal, whitish, soft, with a row of anteroventral, subapical, long, stiff setae (Fig. 5). Labium: Prementum-postmentum articulation reaching posterior margin of procoxae. Prementum reddish brown, subrectangular, slightly longer than its widest part, lateral margins smooth, slightly convex at apical 0.60, slightly sinuate and convergent on basal 0.40, basal margin sinuous (Fig. 6); without a longitudinal, central sulcus on ventral surface, a small, shallow, concavity just below ligula beset with some long setae; ligula poorly developed (Fig. 7), apical margin slightly convex, with a ventral row of 9 reddish brown, short, truncate teeth on middle and a row of short, stout piliform setae; labial palp stout (Fig. 7), reddish brown, mostly glabrous, with some sparse, long, delicate setae on external surface; apical lobe stout, tip rounded and finely serrate, internal margin almost straight with 9–11 small, truncate teeth, external margin gently convex and smooth; movable hook reddish-brown, almost as long as palp, sharp and moderately incurved.

PLATE I. Fig. 1. Epigomphus crepidus : a) Last stadium exuvia, dorsal view; b) F −1 larva showing the complex abdominal color pattern, dorsal view.

PLATE II. Figs. 2–8. Details of the morphology of the F −1 larva of E. crepidus . 2) right antenna, dorsal view; 3) Mandibles, ventrointernal view: a, right mandible, b, left mandible; 4) Left maxilla showing palp and galeolacinia, ventral view; 5) Ventral pad of hypopharynx; 6) Prementum, ventral view; 7) ligula and palps, ventral view; 8 Caudal appendages (female), dorsal view.

Thorax: Prothorax slightly narrower than head, setose on inferior border. Anterior margin of pronotum slightly concave, lateral margins convex and bulging, posterior margin convex; a large, subquadrate glabrous area on each side of midline, remainder of pronotum with sparse, minute, scale-like setae. Synthorax mostly bare, with minute, sparse, scalelike setae and some tufts of long, curled setae on inferior margins, meso- and metaspiracles present. Legs short (when fully extended, hind legs scarcely reaching posterior margin of S7), strongly setose (Fig. 1b), with long, yellow-brown, delicate setae mainly on sides and shorter, stiff, reddish setae mainly on anterior surfaces of tibiae and tarsi; burrowing hooks moderately developed (Fig. 1a); dorsal margins of metafemora same length as metatibiae (Fig. 1a); tarsal formula 2-2-3, claws simple, with a pulvilliform empodium. Wing sheaths scarcely surpassing anterior margin of S4, strongly divergent (Fig. 1a), mostly bare, with sparse, minute scale-like setae, and abundant long, delicate setae on borders.

Abdomen: Yellow-brown, gradually and moderately darkening on middle third of tergites 6–9, the whole surface of S10 dark reddish brown (Fig. 1a), more or less spindle-shaped, ventral surface flat, dorsal surface convex, lacking dorsal protuberances, widest on S5; lateral margins of S1–9 with long, stiff yellowish setae, with scale-like setae on S10, lateral margins of S7–9 serrate, serrations stouter and sharper on S8–9, those of S7–9 ending in slightly divergent, sharply pointed spines increasing in size and robustness posteriorly (Fig. 1a); tergites 2–10 with combined short and long, delicate setae mainly on dorsolateral thirds and also with minute scale-like setae, all of them sparse except on posterior margins where scale-like setae are abundant. Sternites following same color pattern as tergites; sternites 3–8 divided into five plates, sternites 2 and 9 divided into three plates, ventral sutures parallel on 2–3, moderately divergent on 4–8, strongly divergent on 9. Male gonapophyses lacking; female gonapophyses vestigial. Caudal appendages (Figs. 1, 8) dark reddish brown, with abundant setae on internal margins and finely serrate on external margins, pyramidal, sharplypointed, external margins concave, tips of cerci and paraprocts divergent, paraprocts and cerci subequal, epiproct slightly longer; male epiproct with a pair of dorsal tubercles at basal 0.50, rounded apically and divergent at basal 0.30.

Measurements. Exuviae (N= 2): Total length (incl. caudal app.) 23.7–25.0; abdomen (ventral, excl. caudal app.) 14–15; maximum width of head 5.0–5.2; hind femur (lateral) 4.5–4.7; maximum width of abdomen (ventral) 6.8–7.0; epiproct 1.1–1.2, cerci 0.9–1.0, paraprocts 0.9–1.0.

Habitat. Larvae were found in small, shallow streams of 2nd and 3rd order, at sluggish margins in shady places, inhabiting banks of fine sand, mud and black detritus.