Epeorus petersi Sivaruban, Venkataraman & Sivaramakrishnan, 2013

Sivaruban, T., Barathy, S., Arunachalam, M., Venkataraman, K. & Sivaramakrishnan, K. G., 2013, Epeorus petersi, a new species of Heptageniidae (Ephemeroptera) from the Western Ghats of southern India, Zootaxa 3731 (3), pp. 391-394 : 391-394

Epeorus petersi Sivaruban, Venkataraman & Sivaramakrishnan , n. sp.

Male imago (in alcohol). Body length: 13.0 mm; fore wings: 13.5mm; cerci 50.0 mm. Head yellow, area between lateral ocelli and covers of head dark brown ( Fig. 1 ). Scape and pedicel of antennae light brown, flagellum pale. Eyes pale pinkish violet. Basal half of lateral ocelli dark brown, apical half pinkish white; median ocellus pinkish white, apical half white. Thorax: pale yellow, edges brownish yellow; dark brown fuscous stripes on thoracic pleurae; venter pale; mesothoracic sternum pale yellow with lateral reddish brown sub circular maculae. Legs: yellow with dark brown patches; femora brownish yellow with a proximal suboval dark brown macula, a median, transverse, wide dark brown, band and distal edge washed with reddish brown tibiae yellowish brown washed with reddish brown distally; tarsi dark brown except at base, claws yellowish brown. Wings ( Figs. 2, 3 ): membrane of fore and hind wings hyaline, except base of fore wings reddish brown; longitudinal veins and cross veins of fore and hind wings reddish brown, all cross veins between costa and radial sector of fore wings surrounded with narrow, reddish brown clouds, apical of costal and subcostal area of fore wings washed with dark brown; apical of costal area of fore wings with about 15 cross veins. Abdomen ( Fig. 4 ): terga I–IX brownish yellow, tergum X yellowish brown washed with dark brown except sub medially, terga III–IX with median dark brown longitudinal bar tapering posteriorly, terga I–IX with dark brown lateral maculae as in Figure 3 and terga II–VIII with light brown sub median, longitudinal broad band as in Figure 4 ; posterior margin of all terga with a narrow, dark brown band; sterna I–IX with sub median dark brown longitudinal bar, sterna I–VI with sub median paired dark brown dots, sternum X with two sub median, circular, dark brown dots. Genitalia ( Fig. 5 ): pale brown; sub circular reddish brown macula on each forceps base ventrally; forceps washed with brown, pale apically; penis dark brown. The penes are not lobed apically, have no lateral spine like processes and have no short spines ventrally below the apical margin ( Fig. 5 ). Caudal filaments yellowish brown, annulations at articulations darker.

Female imago (in alcohol). Body length: 14.0 mm; fore wings, 15.0 mm; cerci, 25.0 mm. Head pale yellow, area between lateral ocelli and covers of head dark brown. Scape and pedicel of antennae light brown, flagellum pale. Eyes pinkish white. Basal half of lateral ocelli dark brown, apical half white; median ocellus pinkish white in basal half, apical half white. Thorax: brownish yellow; sub median light brown longitudinal band on meso and metathorax; dark brown; fuscous stripes on thoracic pleurae; venter pale as in male imago. Legs: colouration as in male imago, except tarsi yellowish brown. Wings: structure and colouration as in male imago. Abdomen ( Fig. 6 ): terga I–VII and X pinkish brown, terga VIII–IX pale pinkish brown; terga II–X with median reddish brown longitudinal bar tapering posteriorly, terga I–X with reddish brown lateral maculae as in Figure 6 and terga I–VII with light reddish brown, sub median, longitudinal broad band, posterior margin of all terga with a narrow, reddish brown band. Sterna I–X yellowish brown, sterna I–IX with sub median reddish brown longitudinal bar, sterna I–IX with sub median paired reddish brown dots, dots median to the bars. Caudal filaments yellowish brown, annulations at articulations reddish brown.

Mature larva (in alcohol) Head: dorsum yellowish brown, carinae darker, sutures paler, area in between ocelli dark brown. Scape and pedicel of antennae yellowish brown, flagellum light brown. Eyes whitish grey. Venter of the head pale. Thorax: dorsum yellowish brown, venter pale. Legs: femora yellowish-brown, with a pair of dark brown maculae as in Figure 13 ; joints of femora and tibiae dark brown; apices of femora produced into an acute spine; tibiae yellowish brown, tarsi brown, claws with three denticles. Abdomen ( Fig. 7 ): terga yellowish brown, a pair of sub median bars in segment II-VIII, a pale yellow zone around the bars in tergum VI, tergum IX pale yellow, a pair of sub median spines and a median row of sparse setae on segment I–X, terga II–X with dark brown longitudinal bar tapering posteriorly; posterolateral spines on segment II–VII; sterna I–IX with sub median dark brown dots, sternum X with two sub median, circular, light brown dots, dots median to the bars. Gills: lamellae pale, with a broad, sclerotized band along the anterior margin, tracheae and filaments smoky pinkish black ( Figs. 8 and 9 ). Caudal filaments dark brown, annulations at articulations paler.

Etymology. This species is named in honor of Professor W. L. Peters, for his outstanding contribution to the systematics and phylogeny of Ephemeroptera .

Holotype (in alcohol): Male imago (Ref. No. MSUMNH 11), Kumbakkarai, Theni district, Tamilnadu, India, latitude 11 ° 45’ 11.02, longitude 77 ° 20’ 49.51, 14/x/2006. Colls. T. Sivaruban & S. Barathy.

Paratypes (in alcohol): 1 female imago (allotype, Ref.No. MSUMNH13), 6 male imagos, 1 male larva, 4 female larvae (Ref. No. MSUMNH 12), same data as holotype .

Holotype and Paratypes are deposited at Manonmaniam Sundaranar University Museum of Natural History, Manonmaniam Sundaranar University, Alwarkurichi , Tirunelveli , Tamilnadu, Inida .

Ecology. The larvae were collected in a small perennial stream of Kumbakkarai , Theni district, Tamilnadu, India (2– 4 m wide and 0.4 cm depth; water current 0.4m /sec) on the southern Western Ghats. The temperature ranged between 22ºC–25ºC and pH between 6.2–7.5. The substratum component, gravel with rocks. The collection site is moderately impacted with organic pollution due to visit of local people .

Discussion. Epeorus petersi n. sp. can be distinguished from other Oriental species by the following combination of characters. Imago: (1) penes are not lobed apically, without lateral spine like processes and without short spines ventrally, ( Fig. 5 ); (2) longitudinal and cross veins of fore and hind wings reddish brown, all cross veins between costal and radial sector of fore wings surrounded with narrow, reddish brown clouds, apical of cells on costal and subcostal area of fore wings washed with dark brown; and apical of costal area of fore wings with about 15 slanting cross veins ( Fig. 2 ). Larva: (1) abdominal terga yellowish brown, a pair of sub median bars in segment II–VIII, and a pair of sub median spines and a row of sparse setae on posterior margin of segment I–X ( Fig. 7 ); (2) posterolateral spines on abdominal segment II–VII, progressively longer and curved inwards posteriorly ( Fig. 7 ); and (3) posterior edge of the lamellate portion of gill 1 bluntly pointed ( Fig. 8 ).

There have been sporadic descriptions of species of Epeorus from India, especially from Himalayas (e.g. Eaton 1885; Kapur & Kripalani 1963). The only species from Western Ghats, E. gilliesi was described by Braasch (1981) from Khandala of the Northern Western Ghats, located in the state of Maharashtra. Then, Braasch & Soldan (1987) reported the species from Southern Western Ghats, based on an immature larva from Kerala. Epeorus petersi n. sp. is described from the Kumbakkarai stream, extending the range of this genus further down on the southern segment of the Western Ghats.

The larva of E. petersi n. sp. can be differentiated from that of E. gilliesi by the shape of posterior edge of the lamellate portion of gill 1 ( Figs. 8, 9 ), tergal colour pattern ( Figs. 7, 12 ), and by the presence of dorsal femoral patches ( Figs. 13, 14 ). The male imago of E. gilliesi remains unkown.

Figures

FIGURES 1–6. Imagos of E. petersi. 1–5, male imago: 1. Head; 2. Fore wing; 3. Hind wing; 4. Abdominal terga; 5. Genitalia (ventral view); 6. Female imago: abdominal terga.

FIGURES 7–14. Epeorus petersi and Eperorus gilliesi, larvae. 7. Dorsal view of abdomen of E. petersi; 8. Gill I of E. petersi; 9. Gill VII of E. petersi; 10. Gill I of E. gilliesi (after Braasch 1981); 11. Gill VII of E. gilliesi (after Braasch 1981); 12. Dorsal view of abdomen of E. gilliesi (after Braasch 1981); 13. Leg of E. petersi; 14. Femur of E. gilliesi (after Braasch 1981).