Thenus indicus Leach, 1815

Burton, T. E. & Davie, P. J. F., 2007, A revision of the shovel-nosed lobsters of the genus Thenus (Crustacea: Decapoda: Scyllaridae), with descriptions of three new species, Zootaxa 1429 (1), pp. 1-38 : 13-15

Thenus indicus Leach, 1815

( Figs 8A , 9 , 18B, D )

Thenus indicus Leach, 1815: 338 . — Leach, 1816: 401. — Latreille, 1829: 80. — Berthold, 1845: 45; 1847: 26.

Thenus orientalis .— Chan & Yu, 1993: 196–198, col. pl. — Chan, 1998: 1040. — Holthuis, 1991: 227–228 (in part) [not T. orientalis ( Lund, 1793) ].

Material examined. Types. Lectotype, NHM-107h, female (50.5 x 57.2), Indian Ocean, coll. Gen. Th. Hardwicke. Paralectotype, NHM-107a, female (67.6 carapace width), Indian Ocean, coll. Gen. Th. Hardwicke.

Non-type material ZRC-1999.1285, male (69.8 x 84.6), Karachi , Pakistan, T. Burton, July 1993 ; RMNH- D31870, male (42.9 x 53.0), SW Bombay, Indian Ocean ; RMNH-D31870 , male (48.4 x 58.2), SW Bombay, Indian Ocean ; ZRC-1999.0481, female (62.2 x 75.4), beach at junction of Jalan Muara and Jalang Hang Tuah, Padang , Sumatera, Indonesia, T.H. T. Tan (from fishermen), 23.05.1997 ; RMNH-D32264 , male (55.5 x 67.0), NE. Sumatera; ZRC-1999.1289, female (56.0 x 68.7), male (55.1 x 68.0), Gulf of Thailand, 30.01.1962 ; QM- W22124, female (33.4 x 43.2), Gulf of Thailand, 27.1.1993 , S. Chaitiamvong; QM-W24674, female (87.4 c.w.), Gulf of Thailand, 27.1.1993 , S. Chaitiamvong; RMNH-D38706 , female (37.1 x 47.4) , Chonburi; RMNH-D38706 , female (33.7 x 43.3) , Chonburi; ZRC-1999.1286, female (52.5 x 64.1), female (56.3 x 70.1), Pulau Tioman, Malaysia, Voyage 9, 17.09.1926 ; ZRC-1995.977, 3 males (57.3 x 68.8; 48.2 x 59.7; 54.2 x 65.1), 2 females (76.1 x 90.9; 53.0 x 64.0), ovig. female (53.0 x 62.7), off Singapore (purchased from Ponggol Fish Market), P.K.L. Ng, 30.09.1995 ; ZRC-1981.8.14.121–122, male (38.6 x 48.2), Jurong Fish Market, Singapore, K.L.Yeo, March 1981 ; ZRC-1999.1284, female (74.6 x 87.8), male (49.5 x 58.5), South China Sea, 4.11.1955 ; NTOU-unreg., female (74.5 x 93.7), Su-Aou, I-Lan County, N.E. Taiwan, trawled 21.7.1985 , T. Y. Chan; NTOU-unreg., male (59.0 x 73.3), Shin-Ta Kong, Kao-hsiung County, S.W. Taiwan, trawled, 28.12.1982 , J.J. Hwang.

Diagnosis. No spotting on pereiopods; outer face of propodus of P2 having upper-most longitudinal groove bearing obvious setae over at least proximal half. Merus of third maxilliped with a small spine proximally on inner ventral margin; inner margin of ischium prominently dentate along entire length. No single morphometric ratio has been isolated that will exclusively identify this species, but only T. indicus can have ratios that fall outside the following maximum and minimum values: P1 merus width ( MW 1) less than 0.07 carapace length (CL); P3 merus length ( ML 3) more than 0.45 carapace length (CL) (Ratios 10, 11 in Table 6).

Remarks. The specimens identified as Thenus indicus in this study conform morphologically with the lectotype specimen of T. indicus from the British Museum (designated in this paper), and this was further confirmed by the morphometric analysis which placed them all in the same grouping.

There is some confusion over the status of the type material. Holthuis (1991: 227) listed as the holotype a dry specimen (NHM-107a) in the Natural History Museum, London, but with the qualification that ‘it is not fully certain that this specimen is the holotype’, and indeed there is a`?’ written on the label accompanying the specimen. Holthuis did not see the material first-hand but merely reported information supplied in litt. by the then curator, Dr R. Ingle. Dr Ingle presumably overlooked an additional specimen (NHM-107h) apparently with exactly the same provenance as NHM-107a, but which had sometime in the past been returned to alcohol storage. The only locality information given by Leach was “Habitat in mari Indico” ‾ NHM-107a has the locality “Indian Ocean”, whereas NHM-107h has on the label “ India ”. Neither label provides sufficient evidence that one specimen or the other had been exclusively examined for the preparation of the original description. Both specimens were collected by General Thomas Hardwicke who as a contemporary of Leach, had spent many years collecting in India, and donated valuable collections to the British Museum ( Dawson 1946). The bulk of specimens comprising the Hardwicke Bequest came to the British Museum following his death in 1835. However, Hardwicke was actively involved in the scientific life of London, being elected a fellow of the Linnean Society in 1804, and of the Royal Society in 1813. Combined with the fact that he was a major patron of museums during his lifetime, donating a variety of important collections, makes it beyond reasonable doubt that he would have personally known Leach and that he would have brought to his attention the curious lobsters he had found during his service in India. Only two specimens from`India’ or the`Indian Ocean’ were listed in the British Museum collections by White (1847: 67–68), so while Harwicke was not specifically noted by Leach as being the collector of his study material, the evidence is convincing that it was his two specimens that were available to Leach. As Leach (1815) did not nominate a holotype, and there was no indication in the description that could identify a particular specimen, we are designating the better, spirit preserved, female specimen NHM-107h as the lectotype, and the dry female NHM-107a as a paralectotype.

It could be argued that Holthuis’ (1991) listing of NHM-107a as the holotype is a definite lectotype designation under Art. 74(b) of the Code. We would respond, however, that in this case he was merely reporting what he believed to be the case given the information supplied to him, and that his statement ‘it is not fully certain that this specimen is the holotype’ is sufficient to show that he was not, himself, making an objective decision about its type status. Thus the discovery of a pair of syntypes still necessitates a lectotype designation. We have chosen the spirit preserved specimen as the lectotype because: a) it is flexible enough to withstand close scrutiny in the future, should it be necessary, whereas the dry specimen is very fragile and more difficult to examine; b) this is the specimen that has been included in our morphometric analysis, and c) because we expect the ‘wet’ specimen to have a greater chance of long-term survival.

The International Commission of Zoological Nomenclature (2002) has made the following ruling in Opinion 1988 (Case 3135): the name indicus Leach, 1815 , as published in the binomen Thenus indicus (specific name of the type species of Thenus Leach, 1815 ), is hereby placed on the Official List of Specific Names in Zoology.

Distribution. Specimens examined for this study were obtained from Pakistan, India, the Gulf of Thailand, Singapore and Taiwan.

Figures

FIGURE 8. Comparison of the pereiopods of (A) Thenus indicus (QM-W24674, female, 87.4 mm c.w.) and (B) T. parindicus (QM-W7973, male, 62.4 mm c.w.) showing the differing characteristic patterns of setation on the propodi of P1 and P2.

FIGURE 9. Map showing the distribution of Thenus indicus Leach, 1815.

FIGURE 18 A, C, Thenus orientalis (off Singapore); B, D, T. indicus (off Singapore); E. T. parindicus (off Darwin, Australia) F, G, H, T. unimaculatus (off Phuket, Thailand), note the variation in the extent of the purple blotch on the propodus of the pereiopods, always represented by at least a streak on P1 as on H; I, T. australiensis (off Darwin, Australia). J, live specimen presumed to be T. orientalis from Bali, Indonesia; Photographs reproduced with kind permission of Tin- Yam Chan (A, B, C, D) and Roger Steene (J).