Mayfly Species Camelobaetidius maidu

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

Description. Mature nymph with body length: 4.5 – 6.1 mm; caudal filaments length 2.5 – 2.9 mm. Head: Labrum (Fig. 1 a): Broader than long; asymmetrically emarginate on apex, arc of anterodorsal setae with seven simple setae, inner seta longer than rest and extended beyond margin of labrum; intermediate seta present but sometimes missing due to detachment (in this case, the setal socket remains present, see figure 2); numerous small, simple or spatulate setae near posterior and lateral margin; anterior margin with 12 – 18 small, double, frayed setae; lateral margin with 5 – 7 simple setae and 8 – 10 apically frayed long setae; ventral surface with dense arc of short, fine setae near anterior margin; nine small setae near lateral margin; one minute seta on anterior margin on each side of cleft. Left mandible (Fig. 1 b): incisors with seven denticles, first outer one longer than others, middle one very small; prostheca well-developed; no setae between prostheca and mola; several small, simple setae on basal region. Right mandible (Fig. 1 c): incisor with seven denticles, first outer one longer than other denticles, middle one very small; prostheca well-developed; tuft of four long, simple setae between prostheca and mola; molar disk well developed (sensu Sibaja-Araya & Esquivel, 2018: p. 92); few small, simple setae on basal region. Hypopharynx (Fig. 1 d): lingua about 1.5 x width of superlinguae, equal in length to superlinguae, apically pointed, hairy on dorsal and ventral surfaces; superlinguae upper half hairy on dorsal and ventral surfaces and with serrate area at middle of lateral margin. Maxillae (Fig. 1 e): robust; galea with three apical denticles, and two apical rows of setae, some setae of one of these rows large and thick, but others thin, and setae of other row shorter and curved; four setae on lacinia; palp not surpassing apical denticles, segment I short, segment II thick with corrugated margin and several marginal fine setae, segment III elongate with corrugated margin and several marginal fine setae, longer than segment II. Labium (Fig. 3 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 several micropores; segment II with a rounded distomedial projection directed towards third segment, dorsal surface with several fine marginal setae, and about six short simple setae on upper half; ventral surface with several fine marginal setae; segment III short and rounded, more developed than 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 small osmobranchia present at base of each forecoxa; each claw with 6 – 11 denticles (Fig. 3 b). Abdomen: Posterior margin of tergum IV with small, triangular spines subequal in length and simple, fine setae not surpassing length of larger spines (Fig 3 c); paraproct with 5 – 7 sclerotized spines, several micropores and simple, fine setae on dorsal surface, posterior margin with minute triangular spines and two simple fine setae (Fig. 3 d).