Tricorythodes fictus Traver

Tricorythodes fictus Traver

Tricorythodes fictus Traver, 1935:635.

Tricorythodes fictus was described by Traver (1935) from Murry County, Oklahoma based upon male and female imagos. The exact type location of the species is unknown, but was likely the Turner Falls area through which Honey Creek flows. This stream has long been known to aquatic collectors for its diverse fauna and minimally disturbed habitat.

Larvae of Tricorythodes fictus were collected and reared from Honey Creek and several locations in the Hill Country of Central Texas. Larvae appear to prefer small to moderate sized streams with limestone outcrops. Small bits of limestone and other debris can often be found attached to hairs on the thorax and abdomen of this species. Mature larvae were collected during the winter and early spring months, indicating an early season emergence for this species. Tricorythodes fictus is currently known from south­central Oklahoma throughout the Hill Country of Central Texas, south to Chihuahua, Mexico (Randolph and McCafferty, 2000). Additional larval material from south­central Mexico seems to belong to this species, but cannot be determined with certainty at this time because adults are unknown.

Larvae: Body length 3.5–6.0 mm; caudal filaments 2.5–3.0 mm. General color pale yellowish­brown with underlying gray maculation; immature larvae pale with limited gray maculation.

Head: Pale yellow with limited gray maculation; compound eyes remote, widely separated; ocelli clear; antennae approximately 2 to 3 times length of head capsule. Mouthparts: Labrum (Fig. 1) dorsally with long, fine simple setae along lateral margin; row of short, branched setae recessed from anterior margin; ventrally with vertical row of simple, fine setae near mid­line; branched setae along anterior margin. Right mandible (Fig. 2) with outer incisors three­lobed; inner incisor two­lobed; prostheca and molar region as in figure 2; scattered setae on dorsal surface. Left mandible (Fig. 3) with outer incisors fourlobed, mostly fused; inner incisor two­lobed; prostheca arising at base of inner incisor, with thicker base and more setae than on right incisor, but not appearing fused with inner incisor; molar region as in figure 3; scattered setae on dorsal surface. Hypopharynx with long, fine simple setae on anterior surface (Fig. 4); inner basal edge of superlinguae with row of setae. Maxilla (Fig. 5) with one­segmented palp and terminal setae; apex of galealacinia with cluster of fused spines and row of heavy setae. Labium (Fig. 6) with moderately­expanded mentum; numerous long, simple setae along outer margins; glossae and paraglossae subequal in length with numerous long, simple setae; edges of glossae and parglossae jagged; notch between glossae deeper with bottom more rounded than notches between glossae and paraglossae; labial palp three­segmented with long, simple apical setae.

Thorax: Pale­yellowish brown, with hairs along lateral margins. Pronotum with gray maculation along margins and mid­dorsal line; long, simple setae along lateral margins and median transverse ridge. Dorsal surface of forefemur with median transverse row of long setae, inner margin with small setae anteriorly, and outer margin with row of long setae, becoming shorter apically (Fig. 7). Tarsal claws (Fig. 8) with single row of uniform, small, apically flattened denticles numbering 14–16 (with minute apical denticle, slightly separated from primary row, only visible at high magnification). Meso­ and metafemora with few, scattered setae on dorsal surface not forming a distinct row as in forefemur. Meso­ and metaclaws with approximately 10 and 14 denticles, respectively; denticles sometimes flattened.

Abdomen: Terga 2–9 with transverse, anterior gray maculation (much reduced in early instars); scattered hairlike setae present on terga. Dorsal lamella of gill two (operculate gill) subtriangular brownish­yellow with areas near margins shaded grayish­black (Fig. 9) and hairs along most of margin; outer margin with longitudinal ridge and scattered small setae along edge of ridge; inner apex with numerous, long setae. Cerci with row of setae at each annulation. Body frequently covered by thick periphyton biofilm, composed of diatoms, bacteria, fungi, and detritus.

Type Material Examined: Tricorythodes fictus: HOLOTYPE: Murry Co., Oklahoma, 20 March 1932, A. Sandoz, male imago (genitalia removed and slide mounted) (CU).

Other Material Examined: OKLAHOMA: Murry Co., Honey Ck. at Turner Falls Pk., above Falls, 30­iv­1995, DE Baumgardner, 3M, 2F, 1F reared (TAMU). Same but, 21­ iii­1995, 25L (TAMU). Same but, 16­ii­1995, 4M, 3L (TAMU). Same but, 07­ii­1994, 3L, 1M reared (TAMU). TEXAS: Bandera Co., Medina R. @ Hwy. 16, 1 mi. NW Medina, 08­ iii­1997, DE Baumgardner & DE Bowles, 1M (reared), 4F (reared) (TAMU). Montgomery Co., New Caney, Peach Creek at FM 1485, 05 ­i­1997, NA Wiersema, 2M. Hays Co., San Marcos R. @ Cape Rd., San Marcos, 22­ii­1997, DE Baumgardner, 11L (TAMU). Kerr Co., Fessenden Ck. @ Hwy. 41, 19 ­iv­1997, DE Baumgardner and DE Bowles, 1F (reared), 6L (TAMU). Comal Co., Guadalupe R @ Hwy. 311, 20 ­vi­1993, JL Cook, 3L (TAMU). Val Verde Co., Devils River at Devils River State Park, 22­xii­1992, DE Baumgardner, 2L, 2M (TAMU). Val Verde Co., Devils River at Dolan Creek Preserve (TNC), 08­xi­1998, DE Baumgardner, numerous larvae, reared adults (TAMU).