Thenus parindicus, Burton & Davie, 2007

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 : 23-25

Thenus parindicus sp. nov.

( Figs 8B , 13A , 16 , 17C, F , 18E )

Thenus orientalis .— Marshall et al., 1959: 134, 137, col. fig. 1. — Jones, 1990: 265–275 [not T. orientalis ( Lund, 1793) ]. Thenus indicus .— Jones, 1993: 143–155. — Burton, 1996: 499–506 [not T. indicus Leach,1815 ].

Material examined. Holotype: QM-W54, ovig. female (69.5, 87.4), Moreton Bay , J. B. Shattling.

Paratypes: QM-W22125, female (34.4 x 44.3), Dayken, Gulf of Carpentaria, 24.9.1995, J. Robbins; QM- W22126, male (34.5 x 45.2), Dayken , Gulf of Carpentaria , 24.9.1995, J. Robbins; NTM-Cr010463, ovig. female (61.6 x 79.2), male (56.9 x 71.4), W of Booby Is. , Qld , trawled, 10°41.4'S, 141°51.6'E, 10 m, 29.11.1991, A.J. Bruce & R. Williams ; QM-W22135, ovig. female (54.2 x 69.1), eastern Cape York , 11°41.8'S, 145°08.3'E, trawled 32 m over hard bottom, 27.09.1979, Commonwealth Northern Prawn Survey ; QM-W22133, female (60.1 x 76.5), eastern Cape York , 14°42.05'S, 145°04.5'E, trawled 9 m, 18.09.1979, Commonwealth Northern Prawn Survey ; QM-W666, female (69.0 x 88.0), Carmill, NQ, 5.8.1936, L. E. Williams; QM-W7973, male (62.4 c.w), 14 miles E. Yule Pt., 12 miles N. Yorkey's Knob, NE.QLD, Australia, 16°34'S, 145°45'E, 37 m, 19.02.1979, L. R. G. Cannon; QM-W22134, male (50.0 x 63.4), eastern Queensland, no other data; QM-W22136, male (49.1 x 61.2), eastern Queensland, no other data; QM-W22247, male (48.4 x 61.5), eastern Queensland, no other data; QM-W1721, female (67.6 x 85.0), Mooloolaba , SEQ, D. Henderson; QM-W11533, ovig. female (76.5 x 97.9), Moreton Bay , 15.10.1940; QM-W22127, ovig. female (62.1 x 79.5), Moreton Bay , J. B. Shattling; QM-W717, male (69.6 x 77.9), Moreton Island , May 1937; QM-W644, female (77.8 x 95.6), Pinkenba , mouth of Brisbane River , 1.5.1936, W. Neild; QM-W552, female (72.6 x 90.1, 14.4), Moreton Island , 21.3.1935; QM-W531, ovig. female (54.9 x 71.3), Moreton Bay , 4.12.1934, Mr. Buchanan; QM-W22248, male (59.7 x 75.6), Moreton Bay , 13.6.1951, A. Pascoe; QM-W591, male (55.8 x 71.0), Moreton Bay , 16.11.1935, J. Buckley; QM-W1703, male (69.3 x 88.9), Bribie Island , C. Taylor; QM- W16031, male (39.9 x 50.9), Moreton Bay , 25 m depth on muddy bottom, N. Coleman, June 1986; RMNH- D10622, 3 females (43.6 x 56.7, 45.3 x 56.6, 64.0 x 77.5), Meraucke, Papua; NTM-Cr012284, male (58.8 x 74.4), Arafura Sea, 10°40'S, 133°50'E, Stn FO 86-3, 60 m, Taiwanese Stern Trawler THCT, 17.04.1986, T. McGuigan; NTM-Cr012287, female (59.2 x 76.5), Arafura Sea, 10°48.09'S, 133°06.4'E, Stn HL 90-10, 60m, 21.10.1990, H. Larson; NTM-Cr010764, 1 male (35.3 x 46.8), mouth of Wood’s Inlet, N. T., 12°27.8'S, 130°46'E, Stn 57, 4 m, 8.07.1981, beam trawl, R. Williams; NTM-Cr000896, 1 juv. (10.9 x 13.7), 1 female (17.8 x 23.7), 12°58'S, 132°10'E, Arafura Sea, Stn HL 81-22, 27m, 19.10.1981, A.J. Bruce on FV Anson; NTM-Cr001417, 1 juv. (18.0 x 23.8), Arafura Sea, 12°58.0'S, 132°10.0'E, trawled FV Anson, Stn HL 81/29, 27 m, 20.10.1981, H.K. Larson; NTM-Cr001223, 3 males (16.8 x 22.0; 17.9 x 23.5; 18.7 x 24.9), Arafura Sea, 12°58.0'S, 132°10.0'E, trawled FV Anson, Stn HL 81/20, 27 m, 18.10.1981, H.K. Larson; NTM-Cr007168, 1 male (45.0 x 59.7), N. of Groote Island , N. T., 13°25'S, 136°40'E, Stn D 6, Shot 5, 20 m 22.12.1987, NT Fisheries .

Diagnosis. No spotting on pereiopods; outer face of propodus of P2 having upper-most longitudinal groove with setae reduced to thin short line near base, or completely lacking; on P1 setae in upper-most groove extending only over proximal half. Merus of third maxilliped without a small spine proximally on inner ventral margin; inner margin of ischium distally dentate, but smoother and slightly molariform proximally.

Remarks. The lack of the small spine proximally on inner ventral margin of the third maxilliped is the simplest way of distinguishing this species from T. indicus . It is the only non-spotted species occurring in Australian waters, but as it can occur sympatrically with T. indicus (specimens have also been identified from Karachi), there is a need to carefully check specimens. On one or two larger Australian specimens there is a vestigial spine on one or both maxillipeds but this is exceptional, and perhaps indicates the recent loss of this character, which is present on all other species of Thenus .

The other obvious character is the pattern of setation on the legs. In particular in T. parindicus the outer face of the propodus of P1 has the upper-most longitudinal groove with setae reduced to a short thin line near the base, or completely lacking ( Fig. 8B ), whereas in T. indicus the upper-most longitudinal groove has obvious setae over at least the proximal half ( Fig. 8A ). Similarly, in T. parindicus the outer face of the propodus of P2 has the upper-most longitudinal groove completely lacking setae ( Fig. 8B ), whereas in T. indicus the upper-most longitudinal groove has a dense band of setae such that there are two obvious darkly setose lines running in parallel along most of the width of the segment ( Fig. 8A ).

Etymology. Name alludes to the similarity with Thenus indicus .

Distribution. Recorded in Australia from Darwin, the Gulf of Carpentaria, and south to the Clarence River, NSW, eastern Australia; also from waters off Karachi, Pakistan, indicating a much wider distribution in the Indian Ocean ( Fig. 16 ). Appears to be common only as far south as Moreton Bay, athough, there is a record of a single specimen of `Thenus orientalis ’ from off the Clarence River that is presumed to be T. parindicus ( Graham et al. 1993) .

= T. unimaculatus ; aus = T. australiensis ; ind = T. indicus . Numbers in bold are those referred to in the text as significant.

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 13. Third maxillipeds of two species of Thenus, A, T. parindicus, B, T. australiensis. The merus of all species except T. parindicus possesses a small spine (s) proximally on the inner ventral margin, in addition to prominent dentition along the entire length of the inner margin of the ischium (d).

FIGURE 16 Map showing the distribution of Thenus parindicus sp. nov.

FIGURE 17 Dorsal and ventral views of three species of Thenus: A, D, T. australiensis (off Darwin, Australia); B, E, T. unimaculatus (off Phuket, Thailand); C, F. T. parindicus (off Darwin, Australia).

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).