Turbanella erythrothalassia, Hummon, William D., 2011

Hummon, William D., 2011, Marine Gastrotricha of the Near East: 1. Fourteen new species of Macrodasyida and a redescription of Dactylopodola agadasys Hochberg, 2003, ZooKeys 94, pp. 1-59 : 35-36

Turbanella erythrothalassia sp. n. Figure 18

Turbanella EgyA Hummon (2009) [E Med & Red Seas Data Base].

Diagnosis:

Adult Lt 440-486 µm; PhJIn at U33. Body medium-short, slender; head sculptured, with a narrow band of circumcephalic cilia and shallow lateral lobes at U05, but no tentacles; neck constriction greatest along the mid-pharynx; trunk broadest along the mid-body, thining gradually to the caudal base; caudum is slightly cleft, incised from its tips to U98, bearing a medial cone. Glands 36-37 per side, small, inconspicuous. TbA 7 per side, inner-most shorter than the others, on fleshy hands that insert at U11; TbVL 9 per side, with 1 along the fore half and 0 in the rear half of the pharynx, and the other 8 evenly spaced and symmetrically arranged along the intestine, and none behind the anal opening; ‘cirrata’ [ Seitenfüsschen] tubes are short, but present at U35; TbP 7 per side, lengthening medial to lateral, inserting along the trailing edge of each lobe. Locomotor ciliature forms 2 longitudinal bands from buccal cavity to anus. Mouth terminal, of medium width; buccal cavity shallow, mugshaped; walls lightly cuticularized; pharynx broad, with conspicuous basal pharyngeal pores; intestine narrows fore to aft, with a slight bulge at the ventral anus, U92. Hermaphroditic; paired testes extend back from the PhJIn, its vasa deferentia recurving to the fore and probably exiting just behind the PhJIn, sperm sometimes descending in clusters to the base of the vasa deferentia; the bilateral ova occur in the fore-gut region and develop rear to fore; frontal and caudal organs not seen.

Description:

Adult Lt 440-486 µm; L to PhJIn 162-166 µm at U38-U33 (Fig. 18). Body medium-short, slender; head sculpted, with a narrow band of circumcephalic cilia and shallow lateral lobes at U05, but no tentacles; neck constriction greatest along the mid-pharynx; trunk broadest along the mid-body, thinning gradually to the caudal base; caudum is slightly cleft, incised from its tips to U98, bearing a medial cone. Widths of apex /head at turban /trunk at PhJIn /mid-gut /furcal base, tips, and their locations along the body length are: 46 /37 /47 /49 /24, 39 µm at U06 /U16 /U33 /U52 /U96, U100. Glands 36-37 per side, small (diameter 3-4 µm), scattered and inconspicuous.

Adhesive tubes: TbA 7 per side, inner-most shorter than the others, occuring on fleshy hands that insert at U11; TbVL 9 per side (L 10-14 µm), with 1 along the fore half at U11 and 0 along the rear half of the pharynx, and 8 evenly spaced and symmetrically arranged along along the intestine at U40-U91, none behind the anal opening; ‘cirrata’ [ Seitenfüsschen] tubes are present at U35 but short (L 9 µm); TbP 7 per side, lengthening from medial to lateral (L 6-10 µm), arrayed along the rear edge of each lobe.

Ciliature: Mouth is surrounded with short sensory cilia (L 4 µm), with 2 pairs of longer vibratile cilia (L 8-10 µm) per side inserted at the points of head sculpting; ciliary hairs (L 12 µm) form a circumcephalic band at U05; sensory cilia of similar length (L 14-16 µm) occur on the trunk in lateral and dorsal columns, with 20 and 16 per side, respectively. Ventral locomotor cilia (L 8 µm) run rearward in 2 longitudinal bands that trace the lateral body margins, remaining separate throughout, the cilia occurring in transverse rows.

Digestive tract: Mouth terminal, of medium width (18 µm diameter); buccal cavity mugshaped, shallow; walls lightly cuticularized; pharynx broad throughout, with conspicuous basal pharyngeal pores; intestine broadest in the fore-gut, narrowing gradually toward the rear, with a slight bulge at the ventral anus at U92.

Reproductive tract: Hermaphroditic; paired testes extend rearward from the PhJIn, sperm sometimes descending in clusters to the base of the vasa deferentia, male seminal pore not seen; bilateral ovules and ova (to 71 × 18 µm) occur in the fore-gut region and develop rear to fore; neither frontal, nor caudal organs were seen.

Ecology:

Sparse in frequency of occurrence (fewer than 10% of samples), scarce to prevalent in abundance (less than 3-5% to greater than 30% of a sample, sometimes a dominant [dom]); littoral in very fine to medium, medium sorted, clean silicious or corraline sand at low water neap to low water spring, 0-15 cm depth (occasionally in very fine to coarse, poorly sorted sand at mean tide level, 030 cm depth).

Geographical distribution:

RED SEA:EGYPT: {Sharm el-Arab Inside, ^Moon Valley [video], Na’ama Bay N [dom], Na’ama Bay S [2-videos], Sharm el-Naga, Ras Sudr [dom], 'Uyun Musa}; ISRAEL: {N Beach [2-videos]}.

Remarks:

There are five video sequences of Turbanella erythrothalassia sp. n., all from Egypt and Israel in the upper Red Sea. Three of these are available as MPEG 2 (and MPEG 1) from Hummon (2009): #1058 a mature Lectotype adult of Lt=486 µm (LPh=153 µm), collected in June 1994 from Moon Valley, Hurghada, Egypt; #1054 a mature adult of 440 µm (LPh=166 µm) from North Beach, Eilat, Israel; and #1059 a subadult of Lt=413 µm (LPh=145 µm) from Na’ama Bay S. Sinai, Egypt. Turbanella erythrothalassia sp. n. is unusual among members of the genus in having ventral locomotor cilia arranged in transverse lines.

Etymology:

Erythrothalassia (Greek: erythros + thalassa = meaning 'red sea’) referring to the Red Sea in which it was found.

Taxonomic affinities:

Turbanella erythrothalassia sp. n. is the only species in the genus with a sculptured head, having shallow lobes, a PhJIn at U38-U33, a medium mouth, and a body with a mid-pharyngeal neck, which also has TbA 7 per side the inner-most being the shortest; a TbVL formula of 9=1,0/8,0 (1 along the fore half and 0 along the rear half of the pharynx, 8 along the intestine and none behind the anus); with short ‘cirrata’ [ Seitenfüsschen] tubes at U35; and TbP 7 per side, along the rear edge of each caudal lobe; and a caudal cone, but without TbV or TbD. The species nearest Turbanella erythrothalassia sp. n. is Turbanella pacifica Schmidt, 1974, which though somewhat smaller, has a similar body conformation and also lacks TbD; however, they differ in the numbers of adhesive tubes (TbA: 7 in the former, 4-5 in the latter; TbL 9 in the former, with none along the rear pharynx, 12 in the latter, with 1 along the rear pharynx; TbP 7 in the former, with a caudal cone, 6 in the latter, without a caudal cone; ‘cirrata’ tube present in the former, absent in the latter).