Mayfly Species Tricorythodes mosegus (Tricos)

Source: Life stage descriptions, taxonomic notes, and new records for the mayfly family Leptohyphidae (Ephemeroptera)

Larva: Body length 4.5 – 5.5 mm; caudal filaments 2.5 – 3.5 mm. Head: Compound eyes remote, widely separated; ocelli clear. Antennae approximately 2 x length of head capsule. Mouthparts: Labrum (Fig. 19) dorsally with long, fine simple setae along lateral margin; row of elongate, branched setae recessed from anterior margin; ventrally with vertical row of simple, fine setae near mid­line, and row of short, branched setae along anterior margin. Right mandible (Fig. 20) with outer incisors three-lobed; inner incisor two-­lobed; prostheca and molar region as in Fig. 20; scattered setae on dorsal surface. Left mandible (Fig. 21) with outer incisors four-­lobed, mostly fused; inner incisor with two denticles; prostheca arising at base of inner incisor, appearing fused with side of outer incisor; molar region as in Fig. 21; scattered setae on dorsal surface. Hypopharynx with long, fine simple setae on anterior surface (Fig. 22); inner basal edge of superlinguae with row of setae. Maxilla (Fig. 23) with three-­segmented palp and short, terminal setae; apex of galea-­lacinia with two large fused apical spines, row of heavy setae. Labium (Fig. 24) with moderately ­expanded mentum with numerous long, simple setae along outer margins and ventrally; glossae and paraglossae subequal in length with smooth margins; glossae with small fine, simple setae; paraglossae with numerous long, simple setae; notch between glossae slightly deeper and more rounded than notches between glossae and paraglossae; labial palp three­-segmented with long, simple setae. Thorax: Scattered small hairs and setae present. Dorsal surface of forefemur with median transverse row of long setae, inner margin with smaller setae basally and outer margin with row of long setae apically (Fig. 25). Tarsal claws (Fig. 26) with single row of uniform, small flattened denticles numbering 10 – 12. Meso­femora and metafemora with few, scattered setae on dorsal surface not forming a distinct row as in forefemur; meso­claws and metaclaws with approximately 10 and 12 denticles, respectively; denticles sometimes flattened and appear as a single structure. Abdomen: Scattered hair-like setae present on terga. Dorsal lamella of gill 2 (operculate gill) subtriangular, brownish-­yellow with scattered patches of black shading (Fig. 27); outer margin with longitudinal ridge and scattered small setae along edge of ridge; numerous long and short setae along margin of gill. Cerci with row of setae at each annulation.