Sparsorythus srokai Srinivasan & Sivaruban & Barathy & Isack 2021, sp. nov.
Creators: name: Srinivasan, Pandiarajan
name: Sivaruban, T.
name: Barathy, S.
name: Isack, Rajasekaran
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Ephemeroptera
Tricorythidae
Sparsorythus
Sparsorythus srokai

description: Sparsorythus srokai sp. nov. (Figs. 1–3)
Types. Holotype (in alcohol): Female mature nymph (Reg. No. ZSI–SRC/I/E/597), South India, Tamil Nadu, Theni district, Veerapandi River, 9.9663 N & 77.4353 E, 308 m a.s.l; 21/i/2021, P. Srinivasan & R. Isack leg. Paratypes: 1 female nymph (Reg. No. ZSI–SRC/I/E/598), 1 male nymph (AMC ZN 190) and 6 female nymphs (AMC ZN 191), same data as holotype.
Diagnosis. The nymphs of Sparsorythus srokai sp. nov. can be distinguished from all other species of Sparsorythus by the following combination of characters: i) presence of lateral setae in the each segment of caudal filaments (Fig. 3I), ii) dorsal surface of labrum entirely covered with scattered ribbon-like bristles (Fig. 2A& 2B), iii) posterior margin of mesonotum reaching segment III in both sexes (Fig. 1A), and iv) left prostheca with several pointed teeth apically (Fig. 2G).
Mature nymphs (in alcohol): Male body length: 3.3–3.5 mm, female body length: 4.6–4.8 mm (Fig. 1). General body coloration grayish-yellow, ventral side of body pale yellowish. Head: Head wider than long and dark blackish with a transverse yellowish line between the eyes (ratio of length: width is 1: 1.8). Head about twice longer than wide. Head widths: 1.01 mm (male) and 1.41 mm (female). Antenna longer than head length 1.8:1 (male) and 1.7:1 (female). Scape about four times the length of the pedicel. Compound eyes black, ocelli greyish. Eyes of female nymphs are slightly larger than those of male nymphs. Ratio of distance between compound eyes to eye width of male = 2.6:1, female = 3.2:1. Labrum (Fig. 2A) oval, ratio of width: length 2.5:1; dorsal surface entirely covered with scattered ribbon-like bristles (Fig. 2B) and two lateral groups of bristles on the ventral side. Hypopharyngeal lingua as wide as long; divided by long rill in middle and nick at the anterior margin of lingua (Fig. 2C). Maxilla (Fig. 2D) oblong-shaped, approximately 1/3 longer than wide, apical part truncate. Labium (Fig. 2E): Glossae and paraglossae fused into a rounded triangular plate and with two groups of setae on lateral submargin. Labial palps three-segmented. First segment oblong shaped, about 1/3 times shorter than the second one, without any setation. The Second segment curved, apical end pointed bluntly with a row of stout marginal setae at its outer margin and tiny submarginal setae at its inner margin. The third segment is very small, bluntly pointed at the apex, without any setation. Labial plate without any nick in the middle of the anterior margin. Mandibles (Figs. 2F–2J) robust and each with a row of long filtering setae on outer margin; outer incisor of both mandibles triangular, with numerous bristles on ventral side; apex with pair of rounded projections; ventral side of inner incisor with bristles and dorsal side with tiny branched setae; left prostheca (Fig. 2F) asymmetrically wider apically, with several pointed teeth (Fig. 2G) and with three to four bristle-like processes at base (Fig. 2H); length of the left prostheca sub equal to the length of inner incisor; right prostheca (Fig. 2I) notched, extended apically with several pointed teeth, no setae on inner side; length of right prostheca slightly shorter than inner incisor (Fig. 2J). Thorax: Width of pronotum subequal to the width of the head. Wing pad pale yellow with black hypodermal pigmentation in the coastal margins (Fig. 1). Posterior margin of mesonotum overlapping at segment III of both sexes (Fig. 1). Length ratio of femur:tibia:tarsus = 1.8:2.2:1 (forelegs); 1.9:2.1:1 (midlegs); and 2.3:2.6:1 (hindlegs). Femora are flat, shorter than tibiae. Three legs dissimilar in shape and size; hind legs larger than fore and mid legs (Figs. 3A–3C). A transversal row of setae on the fore femoral dorsal surface S–shaped (Fig. 3A). Fore femoral setae about 4.1–4.3 times longer than wide with blunt apex (Fig. 3D). A row of setae on fore tibiae is very thin, sharp and about 0.092 mm in size (Fig. 3E). Dorsal surface of middle and hind femora sparsely covered by spines of variable size (Fig. 3G). Mid and hind femora each with short setae at inner margin and long stout setae at outer margin, a row of stout setae along the outer margin of mid and hind femora irregular. Inner margin of mid and hind tibia with longitudinal row of stout setae, setae about 0.035 mm in length (Fig. 3F). Tarsal claws hooked, bearing 2 median denticles and two lateral subapical teeth. Abdomen: Abdomen not flat, lateral sides on segments II–VII concave, segments VIII–IX cylindrical. Denticles of hind margin of abdominal tergum VII short, either pointed or blunt, or terminated by several points. Gills absent on abdominal segment I; gills present on abdominal segments II–VI. Gills each with dorsal lamella and ventral portion consisting of two branches with numerous lateral filaments (Fig. 3H). Gills absent on segment VII. Caudal filaments: Paracercus slightly longer than cerci. Sexual dimorphism: Cerci and paracercus of males much wider and compressed at the base than those of females. Individual segments of caudal filaments each rounded at the posterior margin with setae on the dorsal surface approximately as long as 1/2 of the length of the segment in the proximal part of the cerci and length of the segment increases on its distal part with setae on the dorsal surface approximately as long as 1/6 of the length of the segment. Setae on the ventral surface approximately as long as 1/5 of the length of the segment (Fig. 3I). Lateral margins with spiky setae about half the length of corresponding segments, with these setae present on both sides of paracercus and cerci.
Egg (Fig. 3J): Egg yellowish; oval shaped, longer than wide measuring 184 μm long and 128 μm wide. The polar cap covers approximately about 1/2 of the egg surface. Egg surface covered with hexagonal structures (Fig. 3K). Egg pole opposite to the polar cap bluntly pointed.
Subimago and imago: Unknown
Etymology. This species is dedicated to Dr. Pavel Sroka for his contribution to Oriental Tricorythidae.
Ecology. The nymphs of Sparsorythus srokai sp. nov. were collected in the River of Veerapandi, Theni district (6–12 m wide, about 10 cm depth). The water temperature ranges between 25°C–28°C and pH 7.2–7.6.
description: Published as part of Srinivasan, Pandiarajan, Sivaruban, T., Barathy, S. & Isack, Rajasekaran, 2021, A new species of Sparsorythus Sroka & Soldán, 2008 (Ephemeroptera: Tricorythidae) from Tamil Nadu, India, pp. 185-191 in Zootaxa 5061 (1) on pages 186-189, DOI: 10.11646/zootaxa.5061.1.11, http://zenodo.org/record/5642150