Tetranemertes paulayi, Cherneva & Ellison & Zattara & Norenburg & Schwartz & Junoy & Maslakova, 2023

Cherneva, Irina, Ellison, Christina I., Zattara, Eduardo E., Norenburg, Jon L., Schwartz, Megan L., Junoy, Juan & Maslakova, Svetlana A., 2023, Seven new species of Tetranemertes Chernyshev, 1992 (Monostilifera, Hoplonemertea, Nemertea) from the Caribbean Sea, western Pacific, and Arabian Sea, and revision of the genus, ZooKeys 1181, pp. 167-200 : 167

Tetranemertes paulayi sp. nov.

Fig. 9A-C

Diagnosis.

Tetranemertes paulayi sp. nov. differs from all other known species of the genus by its orange color, and reddish orange blood vessels. Also, all examined specimens of this species, including the largest, had a pear-shaped rounded basis of central stylet, never bilobed or forked, unlike in larger individuals of most other species of the genus that we have examined. DNA barcoding clearly shows that this species is distinct from the other representatives of the genus (Table 5 ).

Material examined.

Type material in the form of anterior and posterior preserved for histology, and midbody in 95% ethanol is deposited with the Florida Museum of Natural History. Holotype: BOMAN_07013 (UFID 1055), paratype BOMAN_08291 (UFID 1118). See Table 1 for additional specimens, accession numbers, and Table 2 for collecting information.

Description.

External appearance of live specimens. Body is orange-colored (Fig. 9A ), with pigment mostly associated with subepidermal layers and the gut. The epidermis pale and translucent, with small specks of orange color throughout. Smaller individuals are paler in color. Body shape is typical for species of the genus: long and thread-like, widest at the level of cerebral ganglia. Anterior tip bluntly rounded. Cerebral organs far in front of the cerebral ganglia (approximately half-way between the cerebral ganglia and anterior tip of head). A single ventro-lateral cephalic furrow is in front of cerebral ganglia, shaped as a shallow anteriorly directed “V” (Fig. 9B ). Posterior cephalic furrow is lacking. The head is widest at the level of the cephalic furrow. Blood vessels appear orangish red, and stand out against the background of other internal structures, especially in the posterior region.

Rhynchocoel and proboscis. Rhynchocoel limited to the anterior-most part of the body (~ ¼ of body length). Proboscis is very short, with stylet region found immediately posterior to the cerebral ganglia. Basis of central stylet is consistently rounded, never forked or bilobed, even in the largest individuals (4-6 cm long). The stylet shaft is spirally sculpted (Fig. 9C ).

Reproduction. No data.

Habitat.

Coral rubble, vermetid-coralline encrustations on rocks, algal holdfasts, barnacles, and algae, at depths of 0-13 m.

Geographic distribution.

Currently only known from the Arabian Sea (Mirbat, Dhofar Governorate, Oman).

Etymology.

Species is named after Dr. Gustav Paulay for his outstanding contributions to studies of marine invertebrate diversity of the world.

Figures

Figure 9. Tetranemertes arabica sp. nov. and Tetranemertes paulayi sp. nov. from the Arabian Sea (Oman), and Tetranemertes sp. ETP 001 from Eastern Tropical Pacific A-C Tetranemertes paulayi. Individual BOMAN- 07013, holotype, external appearance in life (A), and head compressed under coverglass (B) to show number and arrangement of eyes, and cephalic furrow (arrowhead). Note orange blood vessels (inset, and white arrowheads). Individual BOMAN- 08291, paratype (C), stylets, viewed through the body wall of an individual compressed under coverglass (hence the orange tinge), inset emphasizes sculpted stylets (individual BOMAN- 08302) D-F Tetranemertes arabica. Individual BOMAN- 09099, external appearance in life (D), proboscis armature (E). Inset on E shows sculpted stylets (individual BOMAN- 08030). Individual BOMAN- 08050, head compressed under coverslip to show arrangement of eyes (F). Note the pink tinge to the body wall and proboscis wall, and orangish cerebral ganglia G Tetranemertes sp. ETP 001 from the Pacific coast of Panama (individual SMPP 0632). Scale bars: 3 mm (A); 0.2 mm (B, F); 50 μm (C and insets on C, E); 100 μm (E); 2 mm (D); 0.5 mm (G).