Travisia thailandensis, Plathong & Plathong & Salazar-Vallejo, 2023

Plathong, Jintana, Plathong, Sakanan & Salazar-Vallejo, Sergio I., 2023, Two new species of Travisiidae (Annelida, Sedentaria) from Thailand, Zootaxa 5346 (4), pp. 351-371 : 362-368

publication ID	https://doi.org/ 10.11646/zootaxa.5346.4.1
publication LSID	lsid:zoobank.org:pub:34B011C7-EF58-44AF-BD9A-A028C81B34F5
DOI	https://doi.org/10.5281/zenodo.14179708
persistent identifier	https://treatment.plazi.org/id/03E07E5E-FFE9-5703-FF4D-FBD4601CF82B
treatment provided by	Plazi
scientific name	Travisia thailandensis
status	sp. nov.

Treatment

Travisia thailandensis View in CoL sp. nov.

Figs 8–12 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 View FIGURE 12

Type material. Thailand, Gulf of Thailand. Offshore Petroleum Production Area . Nine specimens, coll. Marine Ecosearch Management Co., Ltd. and TetraTech Inc., mud mixed with sand and shells. Holotype. PSUZC-POL-0349, Sta. GT-T2 (8°54’06”N, 101°29’01”E), 27 Apr. 2011, 72 m. GoogleMaps Paratypes. Eight specimens; PSUZC-POL-0350 (1 spec.), Sta. GT-U9 (8°22’60”N, 101°49’05”E), 22 Mar. 2009, 80 m; GoogleMaps PSUZC-POL-0351 (1 spec., on SEM stub), Sta. GT-UB (8°28’24”N, 101°52’42”E), 25 Mar. 2010, 76 m; GoogleMaps PSUZC-POL-0352 (1 spec., on SEM stub), Sta. GT-T2-2 (8°29’48”N, 101°42’46”E), 9 Sep. 2015, 71 m; GoogleMaps PSUZC-POL-0353 (1 spec.), Sta. GT-T2-3 (8°54’06”N, 101°29’01”E), 27 Apr. 2011, 72 m; GoogleMaps PSUZC-POL-0354 (1 spec., juvenile), Sta. GT-T3 (8°33’52”N, 101°37’02”E), 27 Apr. 2011, 72 m; GoogleMaps PSUZC-POL-0355 (1 spec., juvenile), Sta. GT-I (9°38’49”N, 101°12’59”E), 18 Sep. 2015, 68 m; GoogleMaps PSUZC-POL-0356 (1 spec.), Sta. GT-ER (8°59’51”N, 101°19’12”E), 19 Sep. 2015, 50 m; GoogleMaps PSUZC-POL-0357 (1 spec.) GoogleMaps , Sta. GT-UB-2 (8°28’24”N, 101°53’43”E), 22 Mar. 2020, 80 m. GoogleMaps

Additional material. Thailand, Gulf of Thailand. The offshore Petroleum Production Area , the Gulf of Thailand: 2 specs., juveniles: Sta. GT-FR (8°55’17”N, 101°37’42”E), 20 Mar. 2010, 80 m GoogleMaps ; Sta. GT-W2 (8°29’48”N, 101°42’46”E), 9 Sep. 2015, 71 m. GoogleMaps

Diagnosis. Travisia with cirriform branchiae from chaetiger 2, 21 pairs of branchiae and 26–28 chaetigers. Prostomium small, conical, pointed. Eye spots absent. Mid-ventral groove present. Interramal pores from chaetiger 1, continued throughout body. Lateral neuropodial pores on chaetigers 7–14. Lappets very small, conspicuous. Last two segments achaetous. Pygidium short, without anal cirri.

Description. Holotype complete, 12.9 mm long, 2.9 mm wide, 26 chaetigers. Paratypes all complete: six larger specimens 5.7–14.0 mm long, 1.9–3.4 mm wide, 26 chaetigers and two juvenile paratypes 2.1–3.4 mm long, 1.0– 1.4 mm wide, with 20–24 chaetigers. Body robust, grub-like, mid-ventral groove present from peristomium. Color in alcohol white to light tan, semi-transparent, without pigmentation ( Fig. 8A–B View FIGURE 8 ). Body surface rugose, with transverse rows of small, tightly packed spherical tubercles ( Fig. 9A–B View FIGURE 9 ).

Prostomium small, conical, pointed; nuchal organs small, dorsolateral, slightly everted in two paratypes (PSUZC-POL-0351–2) ( Fig. 10B, D View FIGURE 10 ); eyes absent ( Figs 8A–B View FIGURE 8 , 9A–C View FIGURE 9 ). Mouth between chaetigers 1 and 2 ( Figs 9B–C View FIGURE 9 , 10C View FIGURE 10 ); dorsal lip from ventral portion of segment 1, ventral lip from segment 2. Pharynx everted in one paratype, sac-like, folded, smooth ( Fig. 9C View FIGURE 9 ).

Peristomium annulate, achaetous, rugose, with small, packed, spherical tubercles, appearing in two rows dorsally, anterior row with tubercles conical, posterior one crenulate ( Fig. 10B, D View FIGURE 10 ).

Epidermal tubercles with packs of papillae forming spherical to rounded lobes, visible under stereo microscope. Tubercles arranged in single rows per segmental ring, each tubercle with papillae of various sizes; smaller papillae along anterior edge, larger, more spherical papillae along posterior, lower edge ( Fig. 10A–E View FIGURE 10 ).

Body divided into two regions by shape of neuropodial lappets; anterior region with 14 chaetigers, neuropodial lappets small; chaetiger 1 biannulate, and chaetigers 2–14 triannulate with transverse rows of small, spherical lobes. Posterior region with neuropodial lappets becoming progressively larger. Chaetigers 15 to 18 biannulate, following chaetigers uni-annulate to end of body ( Figs 9A View FIGURE 9 , 10A, D View FIGURE 10 ).

Interramal sensory pores ciliated, present from first chaetiger to last one ( Figs 10A View FIGURE 10 , 11A, C View FIGURE 11 ).

Nephridiopores present along chaetigers 7 to 14 in holotype and paratypes ( Figs 10A View FIGURE 10 , 11A View FIGURE 11 ).

Branchiae cirriform, annulate, 21 pairs along chaetigers 2 to 22. First pair short, increasing in size towards chaetiger 12, decreasing in size along chaetigers 13–22, missing from chaetiger 23. Mid body and posterior branchiae distinct, not hidden between parapodia, last branchiae smallest ( Figs 8A View FIGURE 8 , 9A–C View FIGURE 9 , 10A–B View FIGURE 10 ).

Parapodia biramous. Parapodial lappets round poorly developed with small, low conspicuous lobes along chaetigers 1–14; in chaetigers 15–20 neuropodial lobes larger, then progressively smaller in posterior region ( Figs 10A, D View FIGURE 10 , 11A–B View FIGURE 11 ).

Notochaetae and neurochaetae with long spirally spinulose capillaries, present from chaetiger 1; last two chaetigers achaetous, inserted in a pit, near parapodia. In branchial chaetigers, notochaetae located ahead of branchiae ( Figs 8A View FIGURE 8 , 9A–C View FIGURE 9 , 10A–D View FIGURE 10 , 11A–B, E–F View FIGURE 11 ).

Sperm and egg sacs present in two paratypes (SEM specimens). Sperm sacs abundant, present along anterior chaetigers, with small spermatids, each about 0.6–5 µm in diameter ( Fig. 12A–B View FIGURE 12 ). Other globular structures, herein regarded as oocyte sacs, are 22–31 µm in diameter ( Fig. 12C–E View FIGURE 12 ).

Pygidium short, thick, spiraled, with 3 rings; anus terminal with more than 10 lobes in a circle ( Figs 8A–B View FIGURE 8 , 9A, D–E View FIGURE 9 , 11E–F View FIGURE 11 ).

Variation. Number of chaetigers are invariable in larger specimens have (26 chaetigers); whereas smaller or juveniles have fewer chaetigers (20–24). However, in poorly preserved specimens, it was difficult to count the number of chaetigers.

Etymology. Named after the country where the new species was collected.

Habitat. Found at 50–80 m depth, in muddy sediments mixed with sand and shells, offshore the Gulf of Thailand .

Methyl green staining pattern. Prostomium is colorless. Epidermal papillae on the body and pygidium are stained intensely. Peristomium, anterior lips and chaetiger 1 are dark green ventrally. Rows of large papillae of each segmental annulus are more strongly stained as dark green transverse bands than small papillae. Staining persisted for longer than 7 days ( Fig. 8 View FIGURE 8 ). Staining began to fade from the anterior region before other areas, followed by segmental bands between annulations of the posterior segments.

Remarks. Travisia thailandensis sp. nov. belongs to the group of species having cirriform branchiae and a mid-ventral groove. This group comprises only three species: T. hobsonae Santos, 1977 from Florida, USA, T. fusiformis Kudenov, 1975 , from the Gulf of California, Mexico and the new species, T. thailandensis sp. nov. from the Gulf of Thailand ( Table 3 View TABLE 3 ).

Travisia thailandensis sp. nov. differs from T. hobsonae by having 21 pairs of branchiae, starting from chaetiger 2, and a total of 26 chaetigers. Travisia hobsonae has 28–29 pairs of branchiae starting from chaetiger 3, and a total of 30–31 chaetigers ( Santos 1977; Rizzo & Salazar-Vallejo 2020). Travisia thailandensis sp. nov. also differs from T. hobsonae by having nephridiopores on chaetigers 7–14, while T. hobsonae has nephridiopores on chaetigers 3–14 ( Santos 1977).

Travisia thailandensis sp. nov. differs from T. fusiformis by having 26 chaetigers, whereas T. fusiformis has 34– 35 chaetigers ( Kudenov 1975; Rizzo & Salazar-Vallejo 2020). The new species has 21 pairs of branchiae, whereas T. fusiformis has more than 30 (33–34 pairs) ( Kudenov 1975). Moreover, parapodial lappets in T. thailandensis sp. nov. are poorly developed throughout the body, with very short, low conspicuous lobes, whereas in T. fusiformis , parapodial lappets are well-developed from chaetiger 17 to the end of the body ( Kudenov 1975).

Furthermore, nephridiopores are only present in T. thailandensis sp. nov. on chaetigers 7 to 14, while they are present in T. fusiformis on chaetigers 3 to 14 ( Kudenov 1975). Epidermal papillae in T. thailandensis sp. nov. are rectangular clusters of papillae of various sizes and shapes, whereas those in T. fusiformis are circular in frontal view, set closely together, and are separated by narrow channels.

Also, the pygidium in T. thailandensis sp. nov. is short, spiral and without anal cirri, whereas T. fusiformis has a long, cylindrical pygidium with 6 or 7 flat, digitate papillae ( Kudenov 1975). In addition, the pygidium of T. hobsonae has 5–9 anal papillae of different widths ( Santos 1977). Finally, T. thailandensis sp. nov. is smaller and shorter than both the other species.

Distribution. Only known from the offshore area of the Gulf of Thailand ( Fig. 1 View FIGURE 1 ).