Themiste (Lagenopsis) minor minor (Ikeda)

Hsueh, Pan-Wen & Kuo, Chia-Ming, 2009, New records of sipunculan worms from Taiwan, Zootaxa 2067, pp. 51-61 : 57-58

Themiste (Lagenopsis) minor minor (Ikeda)

Figs. 2 G, 3B

Dendrostoma minor Ikeda, 1904: 154 .

Themiste minor minor Cutler, 1994: 154 (for complete synonymy).

Material examined. One specimen (NMNS-5928-009), Shihmen (25°17.84' N, 121°34.23' E), Taipei County, northwestern Taiwan, lower intertidal sediment rocks, coll. P.-W. Hsueh, 4 November 2007; 11 specimens (NMNS-5928-010), Shihmen (25°17.84' N, 121°34.23' E), Taipei County, northwestern Taiwan, lower intertidal sediment rocks, coll. P.-W. Hsueh, 9 May 2008; 45 specimens (NMNS-5928-011), Shihmen (25°17.84' N, 121°34.23' E), Taipei County, northwestern Taiwan, lower intertidal sediment rocks, coll. P.-W. Hsueh, 10 May 2008.

Remarks. Themiste minor Ikeda and T. variospinosa Edmonds are the only two species in the subgenus Themiste (Lagenopsis) that have introvert hooks. The former species differs from the latter by the presence of posteriorly oriented hooks, and introvert hooks of the other species are orientated in all directions ( Cutler & Cutler 1988: 746, fig. 3A, C; present study, Fig. 3 B). Cutler and Cutler (1988) divided T. minor into two subspecies T. minor minor and T. minor huttonii (Benham) , with the latter having a relatively longer body length (trunk length reaching 55 mm vs. <20 mm), as well as more hooks and a longer hook-bearing region on the introvert (55–75 % vs. 25–35 %). Themiste minor huttonii is known only from Australia, New Zealand and the Chatham Islands in South Pacific Ocean, whereas T. minor minor ranges from across Japan, China, South Australia and southern Africa. Cutler and Cutler (1988) suggested that T. minor minor is a cooltemperate, intertidal and shallow subtidal form but our records show that it also occurs in subtropical waters.

Figures

FIGURE 2. A, Sipunculus robustus Keferstein. B, Siphonosoma funafuti (Shipley). C, Siphonosoma vastum (Selenka and Bülow). D, Golfingia margaritacea margaritacea (Sars). E, Golfingia muricaudata (Southern, 1913). F, Thysanocardia nigra (Ikeda). Scalebars: A-E, 10 mm; F, 2.5 mm. G, Themiste minor minor (Ikeda), H, Phascolosoma arcuatum (Gray). I, Phascolosoma glabrum glabrum (Sluiter). J, Aspidosiphon (Aspidosiphon) muelleri Diesing. K, Aspidosiphon coyi de Quatrefages. Scalebars: G, 5 mm; H – J, 10 mm; K, 2.5 mm.

FIGURE 3. A, Introvert hooks of Siphonosoma vastum (Selenka and Bülow). B, Anterior close-up view of Themiste minor minor (Ikeda), showing posteriorly orientated hooks. C, Introvert hooks of Phascolosoma arcuatum (Gray). D, Introvert hooks of Phascolosoma glabrum glabrum (Sluiter). E, Anal shield of Aspidosiphon muelleri Diesing. F, Introvert unidentate hook of Aspidosiphon muelleri Diesing. G, Anal shield of Aspidosiphon coyi de Quatrefages, showing grooves on the surface of anal shield. H, Introvert hook of Aspidosiphon coyi de Quatrefages, showing a small secondary tooth on the hook. Scalebars: A, 100 μm; B, E, G, 1 mm; C – D, 80 μm; F, 10 μm; H, 20 μm.