Taxonomic studies on Pyrgomorphidae (Orthoptera: Caelifera: Pyrgomorphoidea) from Telangana, India

Introduction

Grasshoppers belonging to the order Orthoptera constitute one of the largest and most diverse groups of phytophagous insects occurring in natural and agricultural ecosystems. Orthopterans play significant ecological roles as herbivores, prey for numerous vertebrate and invertebrate predators and bioindicators of habitat quality. Several species are economically important because they cause considerable damage to cereals, pulses, oilseeds, vegetables and forage crops, whereas others contribute to ecosystem functioning by participating in nutrient cycling and energy transfer (Uvarov, 1966; Dirsh, 1975) [12,4] . The superfamily Pyrgomorphoidea comprises a distinct lineage of short-horned grasshoppers characterized by conical heads, robust bodies, well-developed prosternal processes and considerable variation in wing development. Among its constituent families, Pyrgomorphidae Brunner von Wattenwyl, 1874 is one of the most recognizable groups because of its striking colouration, morphological diversity and host-plant associations. Approximately 500 species distributed among nearly 170 genera have been reported worldwide, with maximum diversity occurring in tropical Africa and Asia (Kevan & Akbar, 1964) [6] . (Akwanjoh, 2018 [1,2,8,10,11,13] India possesses a rich pyrgomorphid fauna owing to its diverse climatic conditions and vegetation types. Classical taxonomic studies by Kirby (1914) [7] , Dirsh (1961) [3] , Kevan and Akbar (1964) [4] , Shishodia et al. (2010) [9] have considerably improved the knowledge of Indian Pyrgomorphidae. Nevertheless, information from the Deccan Plateau, particularly Telangana, remains fragmentary and scattered in regional faunal surveys. Telangana encompasses diverse agro-climatic zones, including dry deciduous forests, scrublands, grasslands and intensively cultivated agricultural landscapes. These habitats support a rich assemblage of grasshopper species, many of which are associated with economically important crops such as maize, paddy, sorghum, pearl millet and pulses. Accurate identification of pyrgomorphid species is essential not only for biodiversity assessment but also for pest management and ecological investigations. Taxonomic studies based on external morphology, morphometric measurements and genital characters continue to provide reliable criteria for species identification despite recent advances in molecular systematics. Comprehensive taxonomic documentation also facilitates biodiversity conservation, faunal inventories and future phylogenetic studies.

Materials and Methods

Field surveys were conducted from October 2020 to January 2021 across the Northern, Central and Southern Telangana Zones, covering agricultural fields of maize, paddy, pearl millet and redgram as well as natural grasslands. Grasshoppers were collected by sweep netting, hand collection and visual searching during morning and evening hours, then transferred to killing jars charged with ethyl acetate and preserved by standard entomological procedures. Specimens were identified under a stereoscopic microscope using the classifications and keys of Kirby (1914) [7] , Dirsh (1961, 1975) [3,4] , Kevan and Akbar (1964) [] , Shishodia et al. (2010) [9] and the Orthoptera Species File. Morphometric data were recorded in millimetres using digital Vernier calipers for body length, antennal length, head length, pronotum length, tegmen length, hind femur length and hind tibia length with measurements taken separately for males and females whenever both sexes were available. Species descriptions were prepared based on external morphology, coloration, diagnostic structures and morphometric observations. Distributional information was compiled from the present collections together with published Indian records. Each species account includes synonymy, diagnosis, material examined, distribution and remarks following current taxonomic conventions.

Family: Pyrgomorphidae Brunner von Wattenwyl, 1874 Family diagnosis

Members of Pyrgomorphidae are medium to large-sized grasshoppers characterized by a conical head, oblique frons, filiform antennae, distinct prosternal process, robust hind femora and well-developed or reduced tegmina and wings. They are predominantly phytophagous and inhabit grasslands as well as cultivated ecosystems.

Subfamily: Pyrgomorphinae Brunner von Wattenwyl, 1874 Subfamily diagnosis

Body small to medium-sized with a conical head, projecting fastigium, filiform antennae, open mesosternal interspace and slender hind femora. Tegmina and wings may be fully developed or reduced.

Genus Atractomorpha Saussure, 1862 Genus diagnosis

Body slender and green with an elongated conical head, elliptical eyes, narrow pronotum and elongated tegmina. Antennae are shorter than the combined length of the head and pronotum.

Atractomorpha crenulata crenulata (Fabricius, 1793) [14] Material examined: Palem, Jagitial, Rajendranagar, Sircilla and Aswaraopeta collected from maize, paddy, bajra, grasses and redgram during October 2020-January 2021.

Diagnosis: Slender bright-green grasshopper with elongated conical head, narrow frontal ridge, elongated pronotum and well-developed tegmina (Plate 1). Females are larger than males. Diagnosis: Large grasshopper with characteristic blue-black and yellow bands on the body, green tegmina, reddish hind wings and yellow hind tibiae (Plate 3).

Morphometrics

Morphometrics: Female body length ranged from 38.48-44.81 mm (mean 42.18 mm) and male body length from 38.28-47.91 mm (mean 42.36 mm). Mean head length was 5.97 mm in females and 6.33 mm in males. Mean pronotum length measured 7.15 mm (female) and 5.62 mm (male). Mean hind femur length was 25.38 mm in females and 23.61 mm in males, while mean hind tibia length measured 25.19 mm and 23.30 mm, respectively. Distribution: Widely distributed in India including Telangana, Andhra Pradesh, Maharashtra, Karnataka, Rajasthan and Tamil Nadu.

Remarks:

The species is readily recognized by its striking aposematic colouration and frequent association with Calotropis species.

Subfamily: Orthacridinae Bolívar, 1905 Subfamily diagnosis

Body elongate, cylindrical and green with a projecting fastigium and reduced or absent wings. Species are generally associated with grasses and shrubs.

Genus Neorthacris Kevan & Singh, 1964 Genus diagnosis

Body cylindrical with projecting fastigium, robust antennae, whip-like male genitalia and green body marked with black longitudinal bands. Wings absent or highly reduced.

Neorthacris acuticeps acuticeps (Bolívar, 1902)

Material examined: Adult specimens collected from Northern and Southern Telangana during 2020-2021.

Diagnosis: Bright green species with elongated head, black longitudinal stripe extending from the eye to abdomen, wingless body and long curved male cerci (Plate 4).

Morphometrics: Detailed morphometric observations showed that females were generally larger than males. Measurements included body length, head length, pronotum length, hind femur and hind tibia, confirming moderate sexual dimorphism within the species.

Distribution: Telangana, Andhra Pradesh and Tamil Nadu. Remarks: This species exhibited a comparatively restricted distribution and was mainly encountered in natural grassland habitats.

Discussion

The present investigation documented four pyrgomorphid species belonging to three genera of Pyrgomorphinae and one genus of Orthacridinae from Telangana. Morphometric comparisons revealed clear sexual dimorphism, with females generally larger than males in all species. Diagnostic characters such as body colour, head morphology, pronotal configuration, tegmina and hind leg measurements proved useful for species delimitation. Atractomorpha crenulata crenulata was the most abundant and widely distributed species, whereas Neorthacris acuticeps acuticeps exhibited a restricted distribution. These observations agree with previous taxonomic accounts of Indian Pyrgomorphidae.

Plate 1: Illustrations of external body parts of Atractomorpha crenulata crenulata (Fabricius, 1793) [14] .

Conclusion

The present study provides an updated taxonomic account of Pyrgomorphidae from Telangana, including diagnoses, morphometric observations and distributional records of four species. The information generated contributes to the documentation of Orthopteran biodiversity and provides a useful reference for future taxonomic, ecological and conservation studies on grasshoppers in India.

References

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