Anisagrion inornatum (Selys, 1876)

Tennessen, Kenneth J., 2012, The nymph of Anisagrion Selys 1876, based on the discovery of A. inornatum (Selys, 1876) in Ecuador (Odonata: Coenagrionidae), Organisms Diversity & Evolution (New York, N. Y.) 12 (3), pp. 297-300 : 297-299

Description of final stadium nymph of Anisagrion inornatum

Relatively stocky nymph, medium brown, head mottled with tan, legs tan, abdomen appearing granular except on two submedian pale stripes ( Fig. 1 ); caudal lamellae markedly tracheated.

Head Maximum width 2.2–2.3 times length (see Methods). Eyes gray-black, unpatterned. Frons predominantly dark to light brown with pale round spot posterior to antennal base. Postero-lateral lobes rounded, each with 12–15 posterior sharp spinules. Antenna 7 segmented, about 2.0 mm long (1.34–1.38 times head length), mostly pale except antm2 dark basally and narrowly along outer margin ( Fig. 2 ); antm3 longest (0.50–0.52 mm), approximate ratios 1: 1.5: 2: 1.2: 0.9: 0.7: 0.5 (antm1 length given a value of 1); a few very fine pale setae on antm1-6. Mandibular formula: L 1 +2 3 4 5 0 a b, R 1 +2 3 4 5 y a. Labium: articulation of prementum/ postmentum lies between bases of coxae II; prementum sub-triangular ( Fig. 3 ), about 5.6 mm long, 4.55 mm wide at anterior widest point (ratio length to maximum width 1.22–1.24); anterior margin strongly convex, finely crenulated; usually 4 large premental setae per side (one side on reared male had two small basal seta and three large distal setae); lateral margin with 12–15 spinules; latero-distal corner (at base of palp) with three or four pale spinules. Labial palp: dorsal margin with five long setae; distal margin between movable hook and distal tooth with six or seven small teeth, three or four small dorsal teeth, and two or three larger ventral teeth ( Fig. 4 ); movable hook curved, 0.6 mm long, about 0.75 times length of outer palpal margin.

Thorax Prothorax and anterior triangular portion of pterothorax tan. Wing pad tips reaching middle of S5. Legs pale, femora without transverse dark bands but with a narrow dark longitudinal stripe on dorsal carina; femora I–III with spinules along longitudinal carinae; tibiae I–III with spinules on carinae plus scattered long, fine pale setae, distally with ventral patch of trifid setae.

Abdomen Cylindrical; S2–8 with 10–16 short spinules on conspicuous dark round bases along lateral carina in an uneven row; dorso-posterior margins of S5–9 with small widely-spaced spinules; S10 elevated posteriorly with median indentation and pale dorso-medial spinules 0.05–0.10 long ( Fig. 5 ). Venter of S1–8 with scattered small spinules; venter of S1–7 each with narrow dark medial stripe. Female cercus triangular in lateral view, 0.42 length of cercus; male cercus more elongate, slightly concave on dorsal surface, 0.55 length of S10. Tips of female gonapophyses reaching posteriorly to level of cercus tip ( Fig. 6 ); outer valves with complete row of 14–18 ventral spines and 4 or 5 longer fine setae, plus a few small setae along sides ( Fig. 6 ). Caudal lamellae membranous, richly tracheated. Median lamella subovate ( Fig. 7a), widest at 0.6 length, ratio of length to maximum width 2.75–2.80; without a discernible nodus; dorsal series of short basal spines about 0.33 length of lamella and consisting of 30 closely based spines, ventral series of spines shorter, extending 0.25 length of lamella and consisting of eight more widely spaced spines; lamella tip abruptly tapered to an acute point, comprising about 0.13 total length of lamella. Lateral caudal lamellae ( Fig. 7b) more lanceolate, 0.44–0.48 length of abdomen, widest at 0.6 lamella length, ratio of length to maximum width 3.0– 3.05; nodus indiscernible; dorsal series of short spines 0.28 length of lamella and consisting of 15 spines, ventral series of spines longer, 0.40 length of lamella and consisting of 40 spines; small stout setae on lateral carina variable in size, series extending from base of lamella to about half its length; tip of lamella similar in shape to that of median lamella except shorter in relation to lamella length (<0.10).

Measurements: (♂ N 0 2, ♀ N 0 3). Total length 11.0– 11.7. Head length 1.40–1.45, maximum width 3.12–3.22. Prementum length 2.2, maximum width 1.8. Femur I: 1.6– 1.7; femur II 2.05–2.15; femur III 2.5–2.7. Abdomen total length 7.0–7.1; S10 length 0.40–0.47; cerci length ♂ 0.26, ♀ 0.17. Median caudal lamella length 5.3–5.4; maximum width 1.93–1.95. Lateral caudal lamella length 5.15–5.30; maximum width 1.68–1.72.

Specimens examined: Anisagrion inornatum : Ecuador, Loja Province, seep along Rio Chamba, Vilcabamba, S04° 15.82', W079° 13.03' (elev. 1555 m); 22/VIII/2008, coll. K.J. T., one ♂ exuviae (reared) [emerged: 3/IV/2008], four final instar nymphs .

Apanisagrion lais : USA, Arizona, Cochise County, Leslie Canyon Rd. , stream, N31° 35.54', W109° 30.40' (elev. 1,417 m), 22/VII/2007, four nymphs, coll. K.J. T .

Figures

Fig. 1 Final stadium nymph of Anisagrion inornatum

Fig. 2 Right antenna of A. inornatum. Bar 0.5 mm

Fig. 3 Prementum of A. inornatum, dorsal view

Fig. 4 Apex of right palpal lobe of A. inornatum, frontal view. Bar 0.25 mm

Fig. 5 Male S10 + basal portion of caudal lamellae of A. inornatum, dorsal view

Fig. 6 Female S9‐10 + gonapophyses of A. inornatum, caudal lamellae omitted, lateral view