Camelobaetidius maidu Jacobus & McCafferty, 2005

Sibaja-Araya, Fabián & Esquivel, Carlos, 2020, Redescription of four species of Camelobaetidius Demoulin, 1966 (Ephemeroptera: Baetidae) from Central and North America, Zootaxa 4758 (2), pp. 257-274 : 258-260

Camelobaetidius maidu Jacobus & McCafferty, 2005

( Figures 1–3 )

Camelobaetidius maidu Jacobus & McCafferty, 2005: 154 ; McCafferty, 2011b: 323.

Diagnosis. Mature nymph. The following combination of characters can be used to diagnose C. maidu from remaining species in the region: 1) labrum with anterior margin with 12–18 small, double, frayed setae; seven setae on anterodorsal arc, 13–17 anterolateral setae; intermediate seta present, though sometimes inconspicuous; numerous small, simple or spatulate setae near posterior margin; ventral surface with about nine short setae near lateral margin; one minute seta on anterior margin on both sides of cleft ( Figs. 1a , 2 ); 2) mandibles with seven denticles on incisors, first outer denticle longer than other denticles ( Fig. 1b, 1c ); 3) maxillary palps with corrugated margin on segment II ( Fig. 1e ); 4) segment II of labial palp with a distomedial projection directed towards third segment ( Figs. 3a ); 5) one small osmobranchia at base of forecoxa; 6) tarsal claws each with with 6–11 denticles ( Fig. 3b ); 7) posterior margin of abdominal tergum IV with small triangular spines subequal in length ( Fig. 3c ); 8) paraproct with 5–7 spines ( Fig. 3d ).

Description. Mature nymph with body length: 4.5–6.1 mm; caudal filaments length 2.5–2.9 mm.

Head: Labrum ( Fig. 1a ): 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. 1b ): 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. 1c ): 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. 1d ): lingua about 1.5x 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. 1e ): 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. 3a ): 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. 3b ).

Abdomen: Posterior margin of tergum IV with small, triangular spines subequal in length and simple, fine setae not surpassing length of larger spines ( Fig 3c ); 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. 3d ).

Distribution: USA and Mexico ( Jacobus & McCafferty, 2005).

Material examined: Paratypes, two mature nymphs (one male and one female); USA, California, Plumas County, North Fork Feather River , XI.2001, (mouthparts in microvial) [ PERC] .

Figures

FIGURE 1. Camelobaetidius maidu Jacobus & McCafferty 2005, nymph. a) labrum (left d. v., right v. v.), b) left mandible, c) right mandible, d) hypopharynx (left d. v., right v. v.), e) maxilla.

FIGURE 2. Camelobaetidius maidu Jacobus & McCafferty 2005, nymph. Labrum with intermediary setae present (white oval) and detached with remaining setal socket (black oval).

FIGURE 3. Camelobaetidius maidu Jacobus & McCafferty 2005, nymph. a) labium (left d. v., right v. v.), b) claws, c) IV tergum spines, d) paraproct.