Carinina ochracea, Sundberg & Chernyshev & Kajihara & Kånneby & Strand, 2009

Sundberg, Per, Chernyshev, Alexey. V., Kajihara, Hiroshi, Kånneby, Tobias & Strand, Malin, 2009, Character-matrix based descriptions of two new nemertean (Nemertea) species, Zoological Journal of the Linnean Society 157 (2), pp. 264-294 : 271-273

CARININA OCHRACEA SP. NOV. ( FIGS 5 , 6 ; TABLE 4)

Holotype: Sexually immature, series of transverse sections GNHM Nemertini 83. Type locality 58°53′124″N, 11°07′275″ E. The 18S rDNA sequence of the species has been deposited with GenBank (accession number EU495306 ) together with sequences of the mtDNA COI gene (accession number EU489492 ).

Further material: Mud and soft bottom, depth from 5 m and down to 40 m. All in the Koster area .

External characters ( Fig. 5 ): The specimen was 13–15 mm long and about 1 mm wide. The body is of more or less uniform width slightly narrowing towards the bluntly rounded posterior tip. The head, which is bluntly rounded, is not wider than the rest of body but sometimes demarcated by a small neck. Posterior half of body yellowish orange with a pronounced transition to orange of anterior half. Lateral margins thin and with same colour as body. Head orange as the anterior part but with reddish touch on margins. Dorsally, the head possesses shallow longitudinal furrows that might be broken, eyes are absent. Proboscis pore subterminal and lies in a small triangular pit on the foremost ventral tip of the head. The mouth, situated further back, is surrounded by wrinkled lips. Individual specimens are slow moving and when mechanically disturbed they first back up and when touched several times they coil in a spiral moving head back and forth. When specimens were fixed they contracted strongly.

Internal characters: Figure 6 , Table 4, and Appendix.

Systematic discussion: We have chosen to place this new species in the genus Carinina based on the two synapomorphies: (1) brain and lateral nerve cords situated in epidermis; (2) longitudinal muscle plate

Carinina Raygibsonia

Character ochracea bergi Figure

1 0 0

2 0 0

3 2 2

4 N/A N/A

5 0 0 & 2

6 2 Not observed

7 01 2

8 N/A 0

9 N/A 0

10 N/A 0 3

11 0 1 3

12 N/A 2 3

13 1 0 3

14 2 1 3

15 2 1 3

16 0 9 3, 5

17 N/A 0 3

18 N/A 1 3

19 N/A 1

20 N/A 0 3

21 N/A 3 3

22 6 5 3, 5

23 0 2

24 1 1

25 0 0 3

26 0 2

27 2 Not seen

28 1 N /A 6A

29 1 N /A

30 0 0 4, 5

31 0 3 4, 5

32 0 N /A

33 2 0 4, 5

34 1 N /A

35 N/A 0

36 N/A 3 4A

37 2 N /A

38 0 0 4, 6

39 1 N /A 6A

40 1 0 8

41 0 1 8, 4A 42 1 1

43 1 2 6B, 4C 44 0 N /A

45 1 2

46 1 0 6C

47 0 1 4D

48 0 0

49 2 2

50 Not seen 1 4C, D 51 1 3

52 0 1 4D

53 N/A 0

54 0 2 4D

55 N/A 0

56 N/A 1

57 N/A 0 8

58 N/A 0 8

59 N/A 1 8

60 N/A 1 8

61 0 0

62 2 0

63 0 1 4A

64 N/A 2 4A

65 1? 0

66 N/A 1 4C

67 N/A 2

68 0 1

present between rhynchocoel and alimentary canal. The phylogenetic analyses in Figures 1 and 7 do not contradict this conclusion. The genus Carinina is currently placed in the taxon Palaeonemertea, but as mentioned above the monophyletic status of the name is unsettled.

The organization of the blood system in this new species is unusual because of the presence of a precerebral unpaired cephalic blood lacuna situated dorsal and lateral to rhynchodaeum; it is randomly pierced by dorsoventral muscle bundles. Just in front of the brain the cephalic lacuna is divided into a pair of lateral cephalic lacunae, and two to three anastomosed ventral lacunae. In the mouth region two ventral lacunae form the vascular plexus, which surrounds foregut and anastomoses with two lateral vessels (lacunae). In the posterior part of the foregut region the vascular plexus disappears. In the foregut region the lateral vessels repeatedly send out branches that penetrate the rhynchocoel wall to form vascular plugs (about ten plugs on left side and about 12 plugs on right side). The only other Carinina species with numerous vascular plugs is Carinina plecta Kajihara (2006) .

Figures

Figure 1. Phylogeny of a selected number of nemertean taxa to show the position of the two new species described here (in bold). Majority rule consensus tree from a Bayesian analysis based on 18S rDNA sequences. Numbers above branches refer to a posteriori probabilities (only values> 95% reported). Three phoronid species were used as outgroup: Phoronis vancouverensis, Phoronis australis, Phoronis hippocrepia.

Figure 5. Carinina ochracea sp. nov. (living specimen).

Figure 6. A–E. Carinina ochracea sp. nov. A, section through cephalic region showing cerebral ganglion and intra-epithelial muscle fibre network. B, section through stomach region showing proboscis and body wall muscle layers. Note the rhynchocoelic villus (arrowhead). C, section through intestinal region showing rhynchocoelic caecum (arrowhead). D, section through intestinal region showing the excretory system. E, section through gonad region of body showing intestine and ova with nucleus (arrowhead). Abbreviations: CG, cerebral ganglion; CM, outer circular muscle layer; D, dermis; E, epidermis; F, follicle; GD, gonoduct; I, intestine; ICM, inner circular muscle; IEMN, intra-epithelial muscle fibre network; LM, longitudinal muscles; LN, lateral nerve cord; LV, lateral blood vessel; MF, muscle fibre; OV, ovum; P, proboscis; PN, protonephridia; R, rhynchocoel; RY, rhynchodaeum; S, stomach.

Figure 7. Phylogeny of a selected number of palaeonemertean taxa to show the position of the new species described here (in bold). Majority rule consensus tree from a Bayesian analysis based on COI mtDNA sequences. Numbers above branches refer to a posteriori probabilities (only values> 95% reported). Outgroup species is Emplectonema neesii.