Janua (Dexiospira) steueri ( Sterzinger, 1909 )

Çinar, Melih Ertan, 2009, Alien polychaete species (Annelida: Polychaeta) on the southern coast of Turkey (Levantine Sea, eastern Mediterranean), with 13 new records for the Mediterranean Sea, Journal of Natural History 43 (37 - 38), pp. 2283-2328 : 2322-2324

Janua (Dexiospira) steueri ( Sterzinger, 1909)

( Figure 14 )

Spiorbis steueri Sterzinger 1909: 1447–1450 , figs 7–11.

Janua (Dexiospira) steueri var. steueri ; Vine 1972: 188–189, fig. 6.

Janua (Dexiospira) steueri ; Vine et al. 1972: 168–170, fig. 11.

Material examined

ESFM-POL /2005-854, 23 September 2005, Anamur, D28, 36°03′37″ N, 32°53′11″ E, 25 m, muddy sand with Udotea petiolata and Caulerpa prolifera , 1 specimen; ESFM- POL/2005-1089, 23 September 2005, Anamur, D29, 36°01′17″ N, 32°48′14″ E, 50 m, muddy sand with C. racemosa , 2 specimens; ESFM-POL /2005-2547, 5 October 2005, Fethiye Bay, K 50, 6 m, P. oceanica , 4 specimens.

Description

Largest specimen complete, 3 mm long; thorax with operculum 1.5 mm long, abdomen 1.5 mm long ( Figure 14A ). From a total of seven specimens, only three with brood chambers, others with juvenile operculum. Tube dextral, whitish, with three longitudinal ridges on top. Outer ridge with projecting blunt processes. Deep indentations between ridges and lateral side of tube ( Figure 14F ). Tube with one whorl. Operculum in juveniles with a slightly concave plate having a bifid talon with calcified wings; bifid projections extending at base of stalk of operculum ( Figure 14B,C ). Talon and wings present in brood chamber of mature worm, transparent ( Figure 14A ). Chamber walls lightly calcified; eggs can be seen, c. 100 µm in diameter ( Figure 14A ). Thorax with three chaetigers. Collar chaetae on convex side having large, simple blades with coarse teeth and faint cross-striations ( Figure 14D ); those on concave side small blades with no cross-striations. Thoracic fascicles with seven or eight finely striated simple chaetae. Thoracic uncini with three or four longitudinal rows of teeth; with a triangular peg at anterior end ( Figure 14E ). Asetigerous region about six times the length of anterior abdominal segments. Abdomen with 12 segments. Geniculate chaetae with a rather broad blade of small teeth. Uncini with five longitudinal rows of teeth and a broad fan at anterior end.

Distribution

This species was previously known from the Pacific Ocean, Indian Ocean and Red Sea (Vine 1972). It is new to the Mediterranean fauna and could have been introduced to the area from the Red Sea.

Figures

Figure 14. Janua (Dexiospira) steueri: (A) whole body, lateral view (ESFM-POL/2005-1089), (B,C) operculum, (D) collar chaeta, (E) thoracic uncini, (F) lateral view of tube. Scale bars: (A) 0.3 mm, (B) 0.37 mm, (C) 0.40 mm, (D,E) 15 µm, (F) 270 µm.