William Benson and the golden age of malacology in British India: Biography, illustrated catalogue and evaluation of his molluscan types

Abstract

William Henry Benson (1803–1870) made extensive collections of Mollusca, particularly land snails, from South Africa, Mauritius, and especially from the Indian subcontinent, where he spent his working life in the service of the East India Company. Benson also received many more molluscan specimens from friends, family and a network of colleagues that included naturalists, physicians, clergy, serving officers in the military and staff of the Geological Survey of India. By this means he obtained material from diverse and often remote parts of India, as well as from Burma, Sri Lanka, China, Malaysia, Borneo, Singapore, Australia, St Helena and Cape Verde. Details of this malacological network are provided, together with a biography of Benson himself and a history of his pioneering role as a malacologist in British India. In a series of papers published between 1829 and his death in 1870, Benson introduced 471 species-level names belonging to 60 families of gastropod and 8 families of bivalve, and in addition introduced names for 32 genus-groups. Of the 102 genus-group names described with Benson species as their types, 70 are currently recognised. Benson’s descriptions were typically rather brief, usually in Latin and almost invariably without illustrations, making it difficult to use them for reliable diagnoses. In keeping with the common practice of the period, he rarely designated individual specimens as types. On his premature return from India in 1847 following a debilitating illness, he gifted numerous specimens to friends and colleagues in various institutions, many of which were gradually acquired over the following decades by the British Museum, later the Natural History Museum, London (NHM). The bulk of Benson’s remaining collection was acquired after his death by Robert McAndrew, who incorporated it into his own huge collection that he bequeathed to the University Museum of Zoology, Cambridge (UMZC) in 1873. The Benson collection suffered badly before it was acquired by the UMZC; most of Benson’s original labels were replaced, resulting in the loss of detailed locality data and presenting difficulties in establishing the type status of many of his specimens. Here, we attempt such an evaluation, through detailed examination of surviving evidence, and provide a comprehensive illustrated catalogue of the taxa described by Benson that can be traced in the UMZC and NHM (and some elsewhere). We provide colour images of type specimens of each species and designate lectotypes and neotypes where appropriate; all such designations proposed here should be attributed to Preece and White. Benson’s taxa are set into a modern systematic framework and some new taxonomic combinations are proposed. Three species are newly synonymised herein: Sitala infula (Benson, 1848) is a junior synonym of S. turbiniformis (Benson, 1838); Carychium boysianum Benson, 1864 is a junior synonym of C. indicum Benson, 1849 and Helix tescorum Benson, 1853 is tentatively considered as a junior synonym of Rhagada torulus (Férussac, 1819). Several new generic combinations are proposed: Cyclostoma liricinctum and C. orbiculatum are attributed to Circulus (Vitrinellidae); Clea annesleyi to Nassodonta (Nassariidae); Cyclostoma milium to Angustopila (Gastrocoptidae); Pupa ofella to Gulella (Streptaxidae); Succinea orientalis to Oxyloma (Succineidae); Pupa diopsis and P. seriola are transferred to Vertigo (Vertiginidae), the first records of this genus from India; P. brevicostis is transferred to Insulipupa (Vertiginidae); and Camptonyx is removed from the Succineidae and provisionally placed in the Lymnaeoidea. Furthermore, we recognise Bullaea caurina Benson, 1842 as having priority over B. exarata Philippi, 1849 and Tanychlamys Benson, 1834 as having priority over Macrochlamys Gray, 1847. The localities from which Benson obtained specimens, together with other important places mentioned, are listed with their pre-colonial and current names (and name variants), their country and state/province, and their geo-coordinates.