Tetranemertes rubrolineata (Kirsteuer, 1965)

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 rubrolineata (Kirsteuer, 1965)

Fig. 3

Nemertes rubrolineata Kirsteuer, 1965: 316; Gibson 1982: 277.

Material examined.

The holotype (in the form of histological sections on slides) deposited at the American Museum of Natural History in New York, USA (AMNH 276) was not examined, as external features and stylet characteristics are not discernible in this material. It is not possible to extract DNA from this material. SAM examined several live specimens from the Arabian Sea ( Mirbat , Dhofar Governorate, Oman), which conform to the description of T. rubrolineata . See Table 1 for specimen details and accession numbers, and Table 2 for collecting information .

Diagnosis.

Body color of living specimens (white or yellowish, with a single, longitudinal, wine-red, dorsal stripe) distinguishes T. rubrolineata from all other described species of the genus except T. unistriata sp. nov. (a look-alike described below). Basis of central stylet thick and bilobed posteriorly ( Kirsteuer 1965: fig. 17), twice as long as stylet. DNA sequence data (or tissue for molecular analysis) are not available for T. rubrolineata from the type locality (Madagascar) but are available for material from Oman that we consider potentially conspecific.

Habitat.

At the type locality (Madagascar) relatively common on Acropora cytherea (Dana, 1846) (syn. Acropora corymbosa ), Acropora pharaonis (Milne Edwards, 1860), Seriatopora hystrix Dana, 1846 (syn. Seriatopora angulata ), and Porites nigrescens Dana, 1846. In southern Oman (Mirbat) among coral and shell rubble at 8-30 m depth.

Geographic distribution.

Madagascar (Tanikely Island, Mozambique Channel), and Arabian Sea (southern Oman).

Etymology.

The species epithet refers to the color pattern of living specimens, specifically the red, mid-dorsal, longitudinal stripe.

Notes.

SAM collected several specimens resembling T. rubrolineata in southern Oman (vicinity of Mirbat) in January 2022 (Fig. 3 ). These individuals had stylets with helical sculpting and a posteriorly bilobed to deeply forked basis of central stylet (Fig. 3C ) in larger individuals (3-4 cm long). The original description of T. rubrolineata depicts a slightly bilobed basis, but does not mention sculpted stylets (perhaps the likely quality of the compound microscope in the primitive field conditions of Tanikely Island in 1959 would have made that observation difficult). Two smaller individuals (1-2 cm long) with an undersized proboscis and armature had a posteriorly rounded cylindrical basis, similar to that observed in the small individual of T. unistriata sp. nov. from Oman.

Figures

Figure 3. Tetranemertes rubrolineata from the Arabian Sea (Oman). Individual BOMAN- 8038 A external appearance in life B head in transmitted light, showing number and distribution of ocelli, as well as ventral cephalic furrow (arrowheads) C stylet armature. Abbreviations: cg - cerebral ganglion, co - cerebral organ. Scale bars: 4 mm (A); 0.25 mm (B); 50 μm (C).