Choroterpes alagarensis Dinakaran, Balachandran & Anbalagan, 2009

Dinakaran, S., Balachandran, C. & Anbalagan, S., 2009, A new species of Choroterpes (Ephemeroptera: Leptophlebiidae) from a tropical stream of south India, Zootaxa 2064 (1), pp. 21-26 : 22-25

Choroterpes alagarensis Dinakaran, Balachandran & Anbalagan , new species

(Figure: 1–12)

Holotype: ♂ imago (in alcohol)

Body length 4.8mm, fore wing 5.0mm. Head: yellowish brown, antenna yellowish brown and transparent, scape and pedicel washed with yellowish brown. Upper portion of eyes dark brown, stalk short, lower portion black. Ocelli pale yellow and their bases whitish. Thorax: pronotum yellowish brown washed with black laterally and on basal margin; meso- and metanota light yellowish brown, margins and carinae darker. Pleura dark brown; thoracic sterna light yellow. Forewing ( Fig. 1 ): membrane hyaline, transparent, dark yellow at base; longitudinal veins transparent dark yellow, cross veins hyaline. Hind wing ( Fig. 2 ): membrane hyaline, dark brown marking on nodus, C and Sc translucent dark yellow in basal half, remaining veins hyaline. Foreleg: Light brown, tarsus lighter; femur with dark brown spots at apical, middle and basal; tarsal formula: 0.4:1.0 (1.5 mm): 0.04: 0.02: 0.15: 0.1: 0.08. Hind legs: transparent yellow, dark brown spots at apical, middle and basal in femora, tibiae light brown at the femoral joint. Abdomen ( Fig. 3 & 4 ): terga transparent brownish yellow, washed with dark brown, with pale median, submedian line and lateral markings. Abdominal sterna transparent yellowish brown, sternum IX with brown basal and lateral margins. Genitalia ( Fig. 5 ): forceps expanded in basal 1/3; styliger plate whitish, forceps and penes yellow. Penis lobes short and membranous. Caudal filaments transparent, light brown.

♂ sub imago (in alcohol)

Colour of ocelli and eyes as in male imago. Head and antennae: light brownish yellow, Thorax: terga yellowish brown, pleura and sterna washed with brownish yellow. Legs as in male imago. Membrane of fore and hind wing translucent yellow, other details of colouration as in male imago. Abdomen: terga light brown, marks on terga as in male imago except dark brown spot on terminal abdominal segment. Colour and marks of sterna as in male imago. Male genitalia: pale yellow. Caudal filament: light brown in colour.

Allotype:

♀ imago (in alcohol)

Body length: 4.4mm to 4.7mm. Fore wing: 6.5mm – 7.5mm. Head: brown, antenna yellowish brown, scape and pedicel washed with yellowish brown, upper portion of the eye yellowish brown, stalk and short, lower portion brown. Ocelli light yellow, and their bases white. Thorax: pronotum yellowish brown washed with black laterally and on basal margin, meso and metanotum light yellowish brown, magins and carinae darker. Pleura light brown, thoracic sterna pale yellow. Fore wing: colour and marks as in male imago except membrane in cells C and Sc longitudinal and cross veins of fore wing darker. Hind wing: colour and marks as in male imago. Fore and hind leg as in male imago except basal marks in femur extend with tibia. Abdomen: terga of segment IV – X opaque brown, terga V–IX light brown, other details of colouration and marks as in male imago. Genital extension light brown, subanal plate blackish white at base, translucent apically, cone shaped without apical notch. Caudal and marks as in male imago.

♀ sub imago (in alcohol)

Colour of antennae, ocelli and eyes as in female imago. Head light brown. Colour and mark of thorax and leg as in female imago but paler. Wing: colour of membrane and veins of fore and hind wings as in male sub imago. Abdomen: terga opaque, light brown, sterna whitish brown, marks as in female imago. Caudal filament light brown.

Mature nymph (in alcohol):

Body length: 5–6mm. Head: light yellowish brown washed with brown, clypeus yellowish and brownish spots present anterior to median ocellus, and pale areas between lateral ocelli and eyes. Antennae yellow, basal segments light yellowish brown. Mouthparts: Labrum ( Fig. 6 ) is expanded and angle laterally, length of labrum slightly more than 1/3 the total width, anteromedian emargination well broad and ‘U’ shaped; mandibles ( Fig. 7 ) with outer margin slightly angled a tuft of setae at angle; maxilla ( Fig. 8 ) with anteriomedian tooth obsolete; hypopharynx as in figure 9; segment of two labial palpi 3/4 the length of segment one, segment three slightly shorter than segment 2, with 3 large dorsal seta on segment 3 ( Fig. 10 ); labrum yellowish brown, basal 2/3 of mandibles brown, outer margin of maxilla, labium yellowish brown. Thorax: terga dark brown, pronotum crescent shaped sub median spots and later margin yellowish brown, mesonotum washed with brown on lateral margin; pleura washed with yellowish brown, sterna yellowish brown. Legs: yellowish white, femora with 3 dark brown spots on apical, median and basal spots, apical and median spot at tibiae and tarsi pale yellow; claw with 2 sections of 15+4 denticles ( Fig. 11 ), with denticles in both sections increasing in size toward apex. Abdomen: terga washed with brown, sterna yellowish brown, male with dark brown at base of each segment, female with sterna washed with yellowish brown, posteriolateral spines present on segment II–IX; gills ( Fig. 12 ) brownish white, trachea brown, secondary trachea lacking side branches, caudal filaments yellowish brown.

Etymology. alagarensis: named for the place of collection, Alagar hills, Tamil Nadu, South India.

Specimens examined. Male imago Holotype labeled India, Tamil Nadu, Nuburagangai stream, 425 m, 10 0 14’180’’N and 77 0 58’567’’E; 10/xii/2006, Col. S. Anbalagan & S. Dinakaran. Female imago Allotype (with nymphal and subimago exuvia) same locality and date as holotype, Col. S. Anbalagan & S. Dinakaran. Paratypes (22 ♂ ♂, 15 ♀ ♀, 65 nymphs): Nuburagangai stream, 12 ♂, 10 ♀ reared with nymphal exuviae; 11 ♂, 9 ♀ ( CRE), Nuburagangai stream, 425 m, 10 0 14’180’’N and 77 0 58’567’’E; 12/xii/2006, Col. S. Anbalagan & S. Dinakaran. 25 nymphs ( CRE), same locality, date and collectors as holotype; 3 ♂, 2 ♀, 17 nymphs ( CRE); Thadaganachiamman stream, 375 m, 8º 57'.938'', 77º 08'.73'', 25/xii/2006, Col. C. Balachandran & S. Anbalagan ; 5 ♂, 3 ♀, 15 nymphs ( CRE); Thalayar , 400 m, 10º 14'.733''N, 77º 30'.98''E, 19/iii/2007 Col. C. Balachandran & S. Anbalagan ; 3 ♂, 1 ♀, 8 nymphs ( CRE); Ayyanar falls , 350 m, 8º 42'.718''N, 77º 07'.29''E, 24/vi/2006, Col. C. Balachandran & S. Anbalagan.

Ecology. This species found in leaf packs, gravels, boulders, submerged roots and woody debris and occurs in slow flowing stream areas. Baetis sp. , Caenis sp. , and Goerodes palnius were associated with this species.

Diagnosis. Choroterpes alagarensis can be separated from Choroterpes nanjingensis by the following combination of characters. In the imago: (1) hind wing dark brown marking on nodus; (2) forceps and penes yellow; (3) penis lobes short. In the nymph: (1) labrum anteromedian emargination well broad and ‘U’ shaped; (2) mandibles with outer margin slightly angled a tuft of setae at angle; (3) apical, median and basal part of femora with dark brown spots.

Figures

FIGURE 1–5. C. alagarensis. 1, fore wing; 2, hind wing; 3, lateral view of male abdominal segments; 4, tergites II – VII of male abdomen; 5, male genitalia.

FIGURE 6–12. Nymph of C. alagarensis. 6, labrum; 7, right mandible, dorsal; 8) maxilla, ventral; 9) hypopharynx, ventral; 10, labium: right, ventral view, 11) fore claw of nymph and 12) gill IV.