Mayfly Species Camelobaetidius mexicanus

Source: Five new species of Camelobaetidius Demoulin, 1966 (Ephemeroptera: Baetidae), and redescription of Camelobaetidius mexicanus (Traver & Edmunds, 1968)

Description. Nymph. Length of body: 2.3 mm; length of antennae: 1.5 mm; length of cerci: broken; length of terminal filament: broken; tibia I: 0.6 mm; tibia II: 0.6 mm; tibia III: 0.6 mm. Head (Figs. 7). Brown. Antennae brown. Lateral branch of epicranial suture straight. Labrum (Fig. 58). Narrowly rounded anteriorly, broader than long. Length about 0.7 × maximum width; lateral margin with long, fine and bifid setae; anterolateral and anterior margin with long, fine, bifid and pectinate setae. Dorsally with four fine, simple setae scattered over basal area; dorsolateral arc of setae with 1 + 8 long, fine and apically pointed setae. Left mandible (Fig. 59). Prostheca robust, apically denticulate. Margin between prostheca and mola without spine-like setae; subtriangular process narrow. Basal half without setae. Right mandible (Fig. 60). Prostheca slender, apically with longitudinal row of denticles; margin between prostheca and mola straight, with three spine-like setae; setae at apex of mola present. Basal half with four simple setae. Hypopharynx (Fig. 61). Lingua little shorter than superlingua; apex broadly pointed, with tuft of short, fine, simple setae. Superlingua not expanded, with fine, simple setae scattered over lateral and distal margin; apex truncated obliquely. Maxilla (Fig. 62). Inner dorsal row of setae with two denti-setae, apical denti-seta at the same orientation of canines. Medial protuberance of galea with 1 + 2 long, fine, simple setae. Maxillary palp 1.1 × length of galealacinia. Labium (Fig. 63). Glossa shorter than paraglossa; inner margin with nine spine-like setae increasing in length distally; apex with two long, spine-like setae; outer margin with five long, spine-like setae; ventral surface with three, fine, simple setae. Paraglossa sub-rectangular, curved inward; apex with two rows of long, fine, setae; ventral surface bare; dorsal surface with five robust, simple setae near apex. Labial palp segment II with distomedial projection rounded and large; dorsally with a row of five fine, spine-like setae; segment III conical, length 0.7 × width, scattered with spine-like setae. Thorax (Figs. 7). Brown. Hind wing pad present. Thoracic gill absent at the base of coxae. Femur brown. Tibia I 0.9 × length of femur I; tarsi I 0.6 × length of femur. Tibia II 0.9 × length of femur II; tarsi II 0.5 × length of femur II. Tibia III 0.9 × length of femur III; tarsi III about 0.5 × length of femur III. Forefemur (Fig. 64). Length about 2.9 × maximum width; dorsally with row of c. a. 40 long, spine-like setae; posterior surface with seven short, spine-like setae near inner margin; ventrally with two short, spine-like setae. Foretibia. Ventrally with 18 short, spine-like setae; anterior surface with nine fine, simple setae near dorsal margin; patella-tibial suture present, 0.5 × length of tibia. Foretarsi. Ventrally with 13 spine-like setae, and one long, fine, simple setae near apex. Tarsal claws (Fig. 64 a) with six denticles, first denticle distinctly longer than others. Mid femur. Length about 2.9 × maximum width; dorsally with row of 40 long, spine-like setae. Hind femur. Length about 2.8 × maximum width; dorsally with row of c. a. 30 long, spine-like setae. Abdomen (Figs. 7). Brown. Terga without creased surface, smooth; posterior margin of tergum IV without spines. Gill oval. Gills IV (Fig. 65) light brown; margins with narrow spines intercalating short, fine, simple setae; tracheae unpigmented. Gill IV 1.7 × length of segment V; gill VII 1.1 × length of segment VIII. Paraproct (Fig. 66). With two spines near inner margin; surface without shagreened area; postero-lateral extension with pointed and rounded marginal spines.