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.

A study of spider species diversity was conducted in some selected localities of in and around Madurai city from October 2019 to March 2020. A total of 29 species of spiders belonging to 22 genera from 6 families were identified from the study sites. Araneidae and Salticidae were found to be the most dominant family with species from 6 and 7 genera respectively. Based on guild structure analysis, Orb-web builders and stalkers were the most dominant feeding guilds. There were considerable disparities in spider species diversity and distribution across all study sites during the study period, with Vadipatti (23 species) having the highest spider species diversity and Kelavasal (7 species) having the lowest diversity. Spider species diversity (Shannon’s index), richness (Margalef’s index) and evenness (Pielou’s index) indices were higher on Vattipatti (2.23; 3.37; 0.46), and least in the Kelavasal (1.11; 1.06; 0.23). Among 29 species, Argiope anasuja, Cyrtophara cicatrosa, Cyrtophora citricola, Gasteracantha geminata and Myrmarachne bengalensis were the most dominant species in Vatipatti and Arasakulam due to the existence of their prey and diverse range of plants, which influenced that these species were more dominant. The present study revealed that spider diversity was higher in rural areas (Vatipatti and Arasakulam) with superior ecological settings, but lower in urban areas (Thiagarajar College campus and Kelavasal) with the most intact ecological environment