Mayfly Species Camelobaetidius variabilis

Source: Redescription of four species of Camelobaetidius Demoulin, 1966 (Ephemeroptera: Baetidae) from Central and North America

Description. Mature nymph body length: 5.6 – 7.0 mm; caudal filaments length 2.4 – 3.2 mm. Head: Labrum (Fig. 4 a): Broader than long; asymmetrically emarginate at apex, arc of anterodorsal setae with seven simple setae, second inner seta extending beyond margin of labrum, further than others; intermediate seta absent; numerous small setae near posterior margin; anterior margin with about 16 small, double frayed setae; lateral margin with 3 simple setae and about 15 apically frayed, long setae; ventral surface with dense arc of short, fine setae near anterior margin; three long setae near lateral margin; minute seta on anterior margin absent. Left mandible (Fig. 4 b): incisors with seven denticles, six similar in size and a middle one very small; prostheca well-developed; no setae between prostheca and mola; numerous small, simple setae on basal region. Right mandible (Fig. 4 c): incisor with seven denticles, six similar in size and a middle one very small; prostheca well developed; tuft of six long, simple setae between prostheca and mola; molar disk well developed; numerous small, simple setae on basal region. Hypopharynx (Fig. 4 d): lingua about 1.8 x wider than superlinguae, equal in length to superlinguae, apically pointed, hairy on dorsal and ventral surfaces; superlinguae with upper half hairy on dorsal and ventral surfaces and serrate area at middle of lateral margin. Maxillae (Fig. 4 e): robust; galea with three apical denticles, and two apical rows of setae, some setae of one of these rows large and thick while others thin, and setae of other row shorter and curved; four setae on lacinia; palp very robust, surpassing apical denticles, segment I short, segment II thick with several marginal fine setae, segment III elongate with several marginal fine setae, longer than segment II. Labium (Fig. 5 a): robust; glossae shorter than paraglossae; both dorsally with numerous elongate and curved setae, ventrally with several elongate and curved setae; palpi with segment I thick, as long as segments II + III, dorsal surface with numerous micropores; segment II with rounded distomedial projection, dorsal surface with several fine marginal setae, and about 4 – 5 short simple setae in upper half; ventral surface with several fine marginal setae; segment III short and rounded, equally developed as distomedial projection, with numerous short, robust spines on ventral surface, dorsal surface with row of short and robust setae on apex. Thorax: Hind wing pads present; one short osmobranchia present at bases of each forecoxa and midcoxa; each claw with 5 – 9 denticles (Fig. 5 b). Abdomen: Posterior margin of tergum IV with rounded spines subequal in length and simple, fine setae surpassing length of longer spines (Fig 5 c); paraproct with 7 – 11 sclerotized spines subequal in length interspersed, several micropores and simple, fine setae on dorsal surface, posterior margin with minute, rounded and triangular spines and three simple, fine setae (Fig. 5 d).