Allomyia renoa ( Milne, 1935 )

Ruiter, David E., Givens, Donald R. & Nishimoto, Hiroyuki, 2021, Redescription of the Allomyia renoa (Milne) female and association and description of the male and larva (Trichoptera: Apataniidae), Insecta Mundi 2021 (883), pp. 1-9 : 2-6

Allomyia renoa ( Milne, 1935)

Diagnosis. Based on the three-part apical segment of the male inferior appendage, this species belongs to the picoides group of Ross (1950) along with A. cidoipes ( Schmid, 1968) and A. picoides ( Ross, 1950) . Schmid’s cidoipes species moniker is an obvious anagram of picoides. Ross (1950) correctly concluded that the A. renoa female was most closely related to A. picoides . Allomyia renoa males are easily separated from A. cidoipes and A. picoides by the broadly separated, narrow, curved ventral rami of the apical inferior appendage of A. renoa , which are most apparent in ventral view.

Redescription. Male ( Fig. 1–5 ): Length 7–9 mm (N = 4). Fresh specimens dark brown in 85% ethyl alcohol (ETOH). Forewing length 7 mm, forewings with pale spots at stigma, just prior to base of forked t3, and arculus. Forewings uniformly clothed with short dark brown setae; hind wings clothed with short black setae. Vertex of head fuscus. Antennae with 41–45 segments; antennae scapes with long, black setae. Basal segment of labial palps with long, black setae. Thoracic nota fuscus. Legs brown; tibiae, tarsi of pro- meso- and metathoracic legs with paired short spines. Segment IX annular, narrow, widest ventromesally and above insertion of inferior appendage. Inferior appendage with basal and apical segments. Basal segment broadly rounded in lateral view, taller than long; with a pair of long, mesally flattened styles originating ventromesally at base, extending beyond apex of basal segment, curved downward throughout, may be sinuous, tapered near apex to acute, downward curved point. Apical segment of inferior appendage consists of three pairs of apical rami. Dorsal rami relatively narrow in lateral view, wider in dorsal view, originating dorsally, subequal to two smaller rami, with stout black, peg-like setae on apical third of ventral surface. Mesal and ventral rami finger-like and curving slightly dorsad throughout length; both with a few black, peg-like setae near apices. Segment X in dorsal view with distal margin apically cleft, tapering to blunt apices, directed posteriorly. Intermediate appendages large, thumb-like, directed laterad. Phallic organ ( Fig. 4–5 ) consists of the phallus sheathed in an endophallic plate, and bordered by paired parameres. Parameres long, thin; apices acute, curved downward throughout in lateral view. Aedeagus mostly membranous, inflated mid-length, with endophallic plate acutely bifid in ventral view.

Female ( Fig. 6–7 ): Length 7and 9 mm (N = 2). Forewing length 7.5 mm. Genitalia generally similar in structure to those of other Allomyia females. Tergum IX separated from sternum IX; fused with segment X near apex, divided to mid-length mesally; in lateral view, base of segment IX longer than tall; dorsal margin tapering abruptly to fused, truncate segment X. In lateral view, sternum IX consisting of setate, quadrate lobe, slightly taller than long; in ventral view triangular, separated mesally from vaginal scale. Vaginal scale three-part, with mesal lobe rectangular, transversely striated, slightly upturned at apex, extending to apex of segment IX lateral lobes; lateral lobes of vaginal scale digitate, curved around base and sides of mesal lobe, smoothly rounded at apex. Supragenital plate long and narrow with smoothly rounded apex. Internal vaginal apparatus (spermatheca) with two parts, ventral part consisting of round, membranous sac in ventral view, likely extensible; dorsal part a keyhole-like sclerotized structure (spermathecal opening).

Pupa ( Fig. 8 ): Length mature pupa 7 and 8 mm (N = 2). Pharate adult with head, thoracic nota blackish-brown. Female antennae extend to anterior margin of abdominal segment VIII. Mandibles reddish-brown, tapering anterad forming a single acute tooth. Lateral line fringe commences on posterior margin of abdominal segment V, extending to anterior margin of segment VII, curving ventrad. Hook plates dark brown, on dorsal abdominal segments III–VII. Pairs of hook plates present anteriorly on segments III–VII; posteriorly on segment V. Hook plate Vp ellipsoidal to circular. Hook plates IIIa each with 5 hooks; IVa with 4 hooks; Va with 3 to 4 hooks; Vp with 14–22 hooks; VI with 5 hooks; VII with 5 hooks. Hook plates IIIa–VIIa with hooks directed posterad; hook plates Vp with hooks directed anterad. Anterior hook plates IIIa–VIIa each with anterior directed stem. Apical process with 2 translucent processes directed posterad.

Larva ( Fig. 9–13 ): Mature larvae 7–13 mm (N = 18).

Head: Head dorsally flattened; dark brown dorsally (in ETOH), paler laterally with no obvious muscle scars; complete carina surrounding dorsal surface; slightly wider than long with eyes located laterally at widest point; eyes located at dorsal margin in lateral view; antennae located closer to mandible than eye; dorsum of head within carina deeply concave, appearing bowl-like, surface with pebbled texture, and entire margin of carina with very short blunt projections. Labrum dark brown, with anterior area yellowish with straw colored setal tufts arising from lateral margins. Mandibles black, without mesal teeth, apically rounded, mesal margins with tuft of white setae.

Thorax: Pronotum with lightly pebbled texture, light brown with dark margin; dark muscle scars present on posterior third; strongly convex, in lateral view with most inflated area near posterior margin; without transverse furrow in anterior third; very few setae present on pronotum, but with fringe of dorsal very fine pale setae (may appear absent). Mesonotum light brown with dark area in posterior lateral corners, lightly pebbled, with setae clearly separated into three setal areas (sa). S a1 discrete consisting of 1 to 2 setae, sa3 discrete with about 3 to 4 long setae; sa2 not discrete, in broad area with a dozen or more scattered setae. Primary setae in positions sa1, sa2, sa3 black, long and slender. Secondary setae in sa2 position black, long and slender (10–15 setae). Metanotal sa1 sclerites inconspicuous, small, with 4–8 setae; sa2 sclerites small, brown, with about 7–12 setae, sa3 sclerites long, narrow, parenthesis shaped, with 12–20 long, slender black setae on anterior portion. Epimeron of metathoracic legs extends ventrad curving beneath coxae. Epimeron with 18–21 long, slender black setae; episternum with 8–17 long, slender black setae. Prosternum with short brown prosternal horn and light brown prosternal sclerite.

Legs: Dark brown; profemora with short, translucent spike-like setae. Pro- meso- and metathoracic trochanters with short, translucent spike-like setae. Procoxae with black primary setae in position 1. Pro- meso- and metatrochanters with black primary setae in positions 2 and 3. Pro- and meso femora with black primary setae in positions 2 and 3; metafemora with black primary setae in positon 4. Pro- meso- and metatarsi with black primary setae in position 2. Pro-meso- and metatibiae with black primary setae in position 3. Meso and metanotal coxae and trochanter without brush of fine setae on ventroapical margin; femora with accessory setae on both anterior and posterior surfaces.

Abdomen: Dorsum of abdominal segment I with 6–18 long, slender black setae laterad to dorsal hump; lateral humps with 4–8 long, slender, black setae; sternum of abdominal segment I with about 40 long, slender, black setae. Abdominal segment II with short, slender black setae in sa2 position. Dorsum of segments III–V appears to be consistently glabrous; segment VI with short, slender black setae in sa2 position; segment VII with short, slender black setae in sa2 position and a single long, slender black seta located laterad; segment VIII with long, slender black setae in position sa2. Dorsum of abdominal segment IX with brown sclerite bearing 10 long, black slender setae along posterior margin; sclerite ellipsoidal in form; posterior margin convex; anterior margin straight; lateral margins rounded. Abdomen with single pairs of gills, dorsally and ventrally on segments III–VI in posterior position; gills may be lacking on dorsum of abdominal segments V and VI. Ventral chloride epithelia present on segments III–VII; dorsal chloride epithelia absent. Lateral sclerite of anal claw brown, slightly crenulate mesally; with 4 long, black slender setae; sole plate brown with single, long, slender seta; anal claw with small accessory hook and a single black seta.

Case: Larval and pupal cases similar, slightly tapered and curved in lateral view, consisting primarily of small sand grains with a few larger stones incorporated, especially laterally at pupation. Posterior end of case membranous with circular hole to allow for flow of water through case.

Material Examined. Specimens examined include: California. Collections made by DR Givens at Lassen Volcanic National Park ( LVNP), Shasta and Tehama Counties , deposited CSUC. Shasta County, King’s Creek LVNP, (Hwy. 89), 40.45952 −121.46954, 28.2 km S of NW entrance to LVNP ( HWY. 89) ; 21-vii-2012, 4 L; 27-vii-2012, 16 L, 01-viii-2012, 1M, 3F, 28 L; 27-v-2013, 1F; 30-vi-2013, 2M, 2F, 2 L; 11-vii-2013, 2 L; 19-vii-2013, 2 P, 6 L; 09-ix-2013, 6 L. King’s Creek at King’s Creek Picnic Site, 40.46133 −121.47683, 28 km S of NW entrance to LVNP, 11-vii-2013, 1 L ; 19-vii-2013, 1 L. Small tributary flowing into King’s Creek in upper meadow, 28.2 km S of NW entrance to LVNP, 28-vi-2013, 2F, 1 P, 1 L ; 29-vi-2013, 2 L; 09-ix-2013, 1 L. Small creek at Paradise Meadow , LVNP, 13-vii-2013. Tehama County, small snowmelt creek 5.47 km N of SW of LVNP entrance (Hwy. 89), 01-vii- 2013, 1M. Nevada. Washoe County , tributary to Galena Creek , about 820.2 m northwest of Mount Rose Ski Area well pad, near Highway 431, Mt. Rose Highway , 39.31948 −119.89963, 27-vi-2017, J. Lee and D. Ruiter collectors, 1 M ( INHS) ; 27-vi-2017, 1 M, 1 F ( MCZ), 1 M, 1F ( DERPC) .

Figures

Figures 1–5. Allomyia renoa (Milne). Male genitalia, scale line = 0.2 mm. 1) Lateral. 2) Dorsal. 3) Ventral. 4–5) Male phallus. 4) Lateral.5) Ventral. Abbreviations: ifa = inferior appendage (paired); ima = intermediate appendage; par = paramere; phl = phallus; IX = segment IX; X = Tergum X.

Figures 6–8. Allomyia renoa (Milne). 6–7) Female genitalia, scale line = 0.2 mm. 6) Lateral. 7) Ventral. 8) Pupal hook plates. Abbreviations: spr = supragenital plate; spr.sct = spermathecal sclerite; ssc.o = spermathecal opening; IXt = tergum IX; Xt = tergum X; III–VII = abdominal terga III through VII; a = anterior; p = posterior.

Figures 9–13. Allomyia renoa (Milne). Larva. 9) Head, oblique view, scale line = 0.5mm. 10) Thorax, dorsal view, scale line = 1.0 mm. 11) Lateral view, scale line = 1.0 mm. 12) Larval case, lateral view, scale line = 1.0 mm. 13) Right pro-, meso- and metathoracic legs. Abbreviation: sl= spike-like setae.