Isonychia (Isonychia) radhae n. sp. is described based on larvae and imagoes from Kapila River, Dakshina Kannada, Karnataka State, India. The imagoes of I. radhae n. sp. can be distinguished from the other known Oriental species by the following combination of characters: (i) absence of rusty brown maculae in the costal, subcostal, and median areas of forewing; (ii) forelegs dark brown except coxae; (iii) Scattered barbs present in penis; (iv) Second segment of gonostylus long and slender; and (v) sterna of abdominal segment X in female not deeply cleft. Isonychia radhae n. sp. can be distinguished in the larval stage from other known Oriental species by the following combination of characters: (i) tergites II–IV without distinct stripe medially, tergites V–X with a pair vague oblique stripe; (ii) abdominal terga II–IX with median dark brown maculae progressively larger with dark brown slanting streaks in lateral margins; (iii) gills I and II small, tracheae of abdominal gills I–VII unbranched; (iv) postero-lateral projection on anterior segments of abdomen blunt and small, acute on segments VIII–IX and large at on segment IX; (v) median terminal filament slightly shorter than 1/3 length of cerci; (vi) distal segments of cerci dark, basal ¾ of mesal margin of cerci and lateral margin of terminal filament with long thin setae. Revised keys to the known larvae and male imagoes of Oriental species of Isonychia are also provided.

A new mayfly species Caenis maduraiensis sp. nov. is described and illustrated from nymph and adults collected from lentic habitat around Madurai. The nymph can be distinguished by the following characters: anterior margin of labrum with row of bipectinate setae longer laterally and a group of highly fringed setae behind emargination; and hind claw long, slender and hooked with row of denticles. Adults are characterized by prosternal triangle with slightly concave sides, tip acutely pointed; apical part of forceps abruptly narrowed to the tip, with a long apical spine, and few trichomes on surface.

The interdigital gland is a specialized skin gland located between the digits of Artiodactyla (i.e., even-toed ungulates). Its secretion participates in semiochemical communication, and protects from ultraviolet radiation as well as fungal and bacterial infection of the feet. The present study aimed at finding if there are male-female differences in the anatomy, morphology, and volatile compounds of the interdigital gland of the South Indian breed of Vembur sheep. A total of 24 sheep (12 each of male and female) were spotted at the slaughterhouse and the interdigital gland was removed for examination. The anatomical examination revealed it to resemble a tobacco pipe and to consist of a body, flexure, and excretory duct with an external orifice located at the cleft of the digits. Morphometrically, the interdigital glands differed between males and females. The gland possesses a distinct fibrous capsule, epidermis, and dermis. The fibrous capsule contains several parallel bundles of collagen fibers, nerve fibers, and blood vessels, etc. The epidermis consists of keratinized squamous epithelium formed of stratum basale, stratum granulosum and stratum spinosum. The dermis consists of hair follicles, nerve plexuses, arrector pili muscles, and apocrine and sebaceous glandular lobules. The latter, lined by a simple cuboidal epithelium, are arranged in clusters of acini in the upper portion of the dermis. The apocrine secretory lobules, made up of parenchymal cells, are found in the lower portion of the dermis. The density and diameter of the apocrine and sebaceous secretory lobules were significantly higher in the males than females. Scanning electron microscopic (SEM) analysis confirmed the apocrine and sebaceous secretory components. Twenty-three major compounds were identified in the interdigital gland postings of male and female sheep, among which butanoic acid, 2-methylpropanoic acid, 1-heptanol and octadecanoic acid were present only in the male glandular post, whereas octane, 7-hexyl-tridecane, tetradecane, heptadecane and decanoic acid were present only in the female glandular post. Tetradecanol, tetradecanoic acid and hexadecanol peaks, reportedly antibacterial compounds in pronghorn antelopes, were highly prominent in both male and female sheep. Thus, the interdigital gland of Vembur sheep has two major secretory lobules, namely, sebaceous and apocrine, larger in males than females, which secrete a variety chemical compounds that may serve as chemical communication systems and protect the sheep from foot-borne diseases.

Two new mayfly species of Clypeocaenis (Ephemeroptera: Caenidae) are described based on nymphal and adult characters from Kaveri River, Kodagu, Karnataka, Southern India. The main characteristics that distinguish Clypeocaenis kaveri sp. nov. from other Oriental species are: (i) fore femur with 4 long spines at middle of inner margin, a row of bifid spines at outer margin and row of bifid spines at subapical surface; (ii) dorsal surface of femora with complete transverse row of bifid setae located 3/4 distance from the base; (iii) forceps smaller than penis lobe. The main characteristics that distinguish Clypeocaenis napoklu sp. nov. from other Oriental species are: (i) fore femur with 2 long spines at middle of inner margin and row of thin setae on outer margin; segment 2 with bifid spine at apex.(ii) dorsal surface of femora with incomplete transverse row of bifid setae located 2/3 distance from the base; (iii) forceps little longer than penis lobe. A key for the nymphs of described species has been provided.

Two new species of Clypeocaenis (Ephemeroptera: Caenidae) are described from Gayathripuzha River, Kerala, and Tunga River, Karnataka, Southern India. The species are best distinguished from congeners based on leg and gill characteristics, as follows. Clypeocaenis gayathri sp. nov.: (1) fore tibia with two rows of ventral and lateral filtering setae, femur with bifid spines, middle tibia with trifurcated spines apically; (2) tracheated gill covers with spines and bifurcated ridges on margins, gills III–VI with more numerous fringed bifid fimbriae. Clypeocaenis sharadhae sp. nov.: (1) fore tibia with two rows of long filtering setae on lateral margin and one row on ventral margin arranged vertically, fore tarsus with transverse row of long setae, hind tibia with a row of lanceolate setae on lateral margin; (2) gills III–VI approximately triangular shaped, with fringed bifid fimbriae, gill III with 12 bifurcated and 2 trifurcated fimbriae.