Epeorus (Caucasiron?) psi (Eaton, 1885)

Figs 17, 18

Iron psi? (Eaton, 1885): Braasch 1980 b: 58.

Epeorus (Belovius) psi (Eaton, 1885): Tshernova 1981: 332.

Epeorus (Caucasiron) psi (Eaton, 1885): Vasanth et al. 2021: 516-519.

Type locality.

India: Kullu district (orig. Kooloo, Himalaya) (Eaton 1883–1888).

Examined material

(deposited in IECA and NMNH NASU). • 20 larvae (barcoded specimens: IN 4, IN 42 - both mounted on slide), 2 male subimagoes (barcoded specimen: IN 44 - genitalia mounted on slide): India: Uttarakhand state, vicinity of Guptkashi town, Madhyamaheshwar Ganga Mandahishvar River – left tributary of Mandakini River, 30°32.27700'N, 79°05.95698'E, 1102 m a. s. l., 15. – 16. 5. 2018, Martynov A. V. leg. (code: IND 2018 / 11) . • 5 larvae (barcoded specimen: IN 43 - mounted on slide): India: Uttarakhand Pradesh, vicinity of Guptkashi village, Mandakini River, 1087 m a. s. l., 30°32.24700'N, 79°05.73900'E, 16. 05. 2018, Martynov A. V. leg. (code: IND 2018 / 12) .

Distribution, habitat, and biology.

Himalayas: India (Eaton 1883–1888; Vasanth et al. 2021), Nepal (Braasch 1980 b, 1981), south-east Tibet (Ma and Zhou 2022); Hengduan Shan and Yunnan-Guizhou Plateau: China (Ma and Zhou 2022) (Fig. 1). The species inhabits mountain streams and rivers in relatively wide altitudinal range. The altitude of the sampling sites ranged between 488 and 2100 m a. s. l. (our data; Braasch 1980 b, 1981; Vasanth et al. 2021). Adults were recorded in May (Braasch 1980 b).

Main morphological diagnostics of the larva.

i) abdominal sterna with a pair of oblique stripes and a longitudinal median line (sometimes reduced anteriorly) (Fig. 17 H), ii) coloration of abdominal terga as on Fig. 17 G), posterior margin of abdominal terga with basally denticulate spines and shorter denticles (Fig. 18 F), iv) tergum X with a short posterolateral projection (Fig. 18 L, arrow), v) gill plates VII narrow (in natural position from ventral view) (Figs 17 I, 18 J), vi) projection on gill plates III well-developed (Fig. 18 H, arrow), vii) femora with median femur spot (Fig. 17 F), viii) dorsal surface of femora with lanceolate (sporadically elongated spatulate) setae (Fig. 18 D), ix) abdominal terga with elongated spatulate and lanceolate setae (Fig. 18 E), femora with an extended and pointed dorso-apical projection (Figs 17 F, 18 M).

Remarks.

Morphology. The species was originally described by Eaton (1883–1888) based on male and female imago. The larva and the male subimago were later described by Braasch (1980 b) from Nepal. Association with imagoes of E. psi was based on the specific pattern of colouration on abdomen and the shape of penis lobes.

Taxonomy. The species was attributed to the subgenus Iron within its own species group “ Iron psi - Gruppe ” (Braasch 1980 b, 2006 b). Vasanth et al. (2021) examined the morphology of larvae and assigned the species to the subgenus Caucasiron based on “ the shape of gills II – VII with an outer thumb-like projection ”. Although the shape of gill plates II – VII is similar to those of E. (Caucasiron), male genitalia with bifurcated penis lobes and extended latero-apical tip, as figured by Eaton (1883–1888) and described by Braasch (1980 b, 2006 b), are not consistent with the diagnosis of E. (Caucasiron) as given by Kluge (1997, 2015). Therefore, the systematic position of E. psi remains unclear until the systematic revision based on molecular data is available.

Distribution. Specimens from Taiwan identified as E. psi by Ulmer (1912) were later described as E. erratus Braasch, 1981 .