Sparsorythus srokai, Srinivasan & Sivaruban & Barathy & Isack, 2021

Srinivasan, Pandiarajan, Sivaruban, T., Barathy, S. & Isack, Rajasekaran, 2021, A new species of Sparsorythus Sroka & Soldán, 2008 (Ephemeroptera: Tricorythidae) from Tamil Nadu, India, Zootaxa 5061 (1), pp. 185-191 : 186-189

publication ID	https://doi.org/ 10.11646/zootaxa.5061.1.11
publication LSID	lsid:zoobank.org:pub:43A13AB8-513E-4DB7-AEA1-1244A21C15E1
DOI	https://doi.org/10.5281/zenodo.5699115
persistent identifier	https://treatment.plazi.org/id/613287F8-4553-084E-FF67-C0CEFAB8F93C
treatment provided by	Plazi
scientific name	Sparsorythus srokai
status	sp. nov.

Treatment

Sparsorythus srokai sp. nov. ( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 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. GoogleMaps Paratypes: 1 female nymph (Reg. No. ZSI–SRC/I/E/598), 1 male nymph ( AMC ZN 190 View Materials ) and 6 female nymphs ( AMC ZN 191 View Materials ), same data as holotype GoogleMaps .

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 View FIGURE 3 ), ii) dorsal surface of labrum entirely covered with scattered ribbon-like bristles ( Fig. 2A& 2B View FIGURE 2 ), iii) posterior margin of mesonotum reaching segment III in both sexes ( Fig. 1A View FIGURE 1 ), and iv) left prostheca with several pointed teeth apically ( Fig. 2G View FIGURE 2 ).

Mature nymphs (in alcohol): Male body length: 3.3–3.5 mm, female body length: 4.6–4.8 mm ( Fig. 1 View FIGURE 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 View FIGURE 2 ) oval, ratio of width: length 2.5:1; dorsal surface entirely covered with scattered ribbon-like bristles ( Fig. 2B View FIGURE 2 ) 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 View FIGURE 2 ). Maxilla ( Fig. 2D View FIGURE 2 ) oblong-shaped, approximately 1/3 longer than wide, apical part truncate. Labium ( Fig. 2E View FIGURE 2 ): 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 View FIGURE 2 ) 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 View FIGURE 2 ) asymmetrically wider apically, with several pointed teeth ( Fig. 2G View FIGURE 2 ) and with three to four bristle-like processes at base ( Fig. 2H View FIGURE 2 ); length of the left prostheca sub equal to the length of inner incisor; right prostheca ( Fig. 2I View FIGURE 2 ) notched, extended apically with several pointed teeth, no setae on inner side; length of right prostheca slightly shorter than inner incisor ( Fig. 2J View FIGURE 2 ). 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 View FIGURE 1 ). Posterior margin of mesonotum overlapping at segment III of both sexes ( Fig. 1 View FIGURE 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 View FIGURE 3 ). A transversal row of setae on the fore femoral dorsal surface S–shaped ( Fig. 3A View FIGURE 3 ). Fore femoral setae about 4.1–4.3 times longer than wide with blunt apex ( Fig. 3D View FIGURE 3 ). A row of setae on fore tibiae is very thin, sharp and about 0.092 mm in size ( Fig. 3E View FIGURE 3 ). Dorsal surface of middle and hind femora sparsely covered by spines of variable size ( Fig. 3G View FIGURE 3 ). 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 View FIGURE 3 ). 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 View FIGURE 3 ). 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 View FIGURE 3 ). 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 View FIGURE 3 ): 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 View FIGURE 3 ). 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.