Travisia satunensis, 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 : 355-362

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.14179704
persistent identifier	https://treatment.plazi.org/id/019821D2-6EF4-440D-8352-F767222AEC53
taxon LSID	lsid:zoobank.org:act:019821D2-6EF4-440D-8352-F767222AEC53
treatment provided by	Plazi
scientific name	Travisia satunensis
status	sp. nov.

Treatment

Travisia satunensis View in CoL sp. nov.

Figs 2–7 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7

urn:lsid:zoobank.org:act:019821D2-6EF4-440D-8352-F767222AEC53

Material examined. Thailand, Andaman Sea. Mu Ko Phetra National Park, Pak Bara Bay. Eleven specimens, coll. Marine National Park Operation Center, Trang, SCUBA diving, fine mud mixed with fine sand. Holotype: PSUZC-POL-0358, Sta. PAK-04 (6°50’06”N, 99°43’58”E), 6 Jan. 2012, 2 m GoogleMaps . Paratypes: ten specimens; Sta. PAK-01 (6°49’42”N, 99°43’07”E), 5 Jan. 2012, 2 m; PSUZC-POL-0359 (1 spec.), Sta. PAK-01 (B1); PSUZC-POL-0360 (2 specs., 1 spec. on SEM stub), Sta. PAK-01 (B2); PSUZC-POL-0361 (1 spec.), Sta. PAK-01 (B3); Sta. PAK‐04 (same locality as holotype); PSUZC-POL-0362 (2 specs., 1 on SEM stub), Sta. PAK-04 (B1); PSUZC-POL-0363 (3 specs., 2 specs. on SEM stubs), Sta. PAK-04 (B3); PSUZC-POL-0364 (1 spec.), Sta. PAK-05 (6°50’33”N, 99°43’07”E), 17 Feb. 2018, 2.7 m GoogleMaps .

Additional material. Thailand, Andaman Sea. Previously identified as T. cf. japonica Fujiwara, 1933 . Sta. 1026 (6°59’11”– 6°58’39”N, 99°31’00”– 99°30’26”E), 18 Jan. 1966, 14 m: PMBC-12393 (1 spec.); PMBC-12403 (1 spec.), 18 Jan. 1996; Sta. 1037 (7°43’54”– 7°44’18”N, 98°57’36– 98°57’35”E), 22 Jan. 1966, 12 m: PMBC-12399 (1 spec.); PMBC-12404 (2 specs.). All label as T. cf. japonica Fujiwara, 1933 .

Diagnosis. Travisia with branched branchiae from chaetiger 2; last two chaetigers without branchiae. Parapodial lappets well developed from chaetiger 15. Pygidium with 10 anal cirri alternately arranged: six digitiform and four short cirri.

Description. Holotype complete, 30.6 mm long, 7.4 mm wide, 37 chaetigers. Paratypes complete, 9.7–16.1 mm long, 1.1–2.7 mm wide, 35–37 chaetigers. Non-type specimens small, about 6.0– 10.3 mm long and 1–3 mm wide, 35 chaetigers. Body long stout ( Figs 2A– B View FIGURE 2 , 4A, C View FIGURE 4 ); integument with small epidermal polygonal papillae, visible under stereo microscope, each 16–29 µm in diameter ( Fig. 4F View FIGURE 4 ). Body light tan, without pigmentation in alcohol.

Prostomium small, conical, acute ( Figs 2C–E View FIGURE 2 , 3A View FIGURE 3 , 4B View FIGURE 4 ); nuchal organs small, round. Eyes absent. Mouth located ventrally at chaetiger 2 ( Figs 2E View FIGURE 2 , 4C–D View FIGURE 4 ).

Anterior region with 14 chaetigers, triannulate, except chaetiger 1. First six chaetigers longer than following ones, weakly triannulate. Chaetigers 15 to 26 biannulate; following chaetigers uni-annulate to pygidium ( Figs 2A– C View FIGURE 2 , 4A, C, E View FIGURE 4 , 5A View FIGURE 5 ).

Interramal sensory pores large (visible under stereo microscope), present between notochaetae and neurochaetae from chaetiger 1 and throughout body ( Figs 2D View FIGURE 2 , 3A–B View FIGURE 3 , 4E View FIGURE 4 ).

Lateral nephridial pores present along chaetigers 3 to 14, most small, conspicuous along chaetigers 3–6, markedly larger on chaetigers 7–10, then becoming small conspicuous pores from chaetiger 11 to chaetiger 14 ( Fig. 2C View FIGURE 2 ). Posterior chaetigers without neuropodial pores. Neuropodial pores not visible on paratypes.

Branchiae all branched annulate, each ring with a single filament subdistal ring without filament; 34 pairs of branchiae starting from chaetiger 2, continue throughout body, missing in last two chaetigers. First branchiae smaller than second branchiae, and progressively larger through mid-body chaetigers ( Figs 2F View FIGURE 2 , 3D View FIGURE 3 , 4E View FIGURE 4 , 5A–C View FIGURE 5 ). Most branchiae longer than notopodial lappets. From chaetiger 26, branchiae becoming progressively shorter than parapodial lappets, hidden together with chaetae between parapodia ( Figs 2G View FIGURE 2 , 3C–D View FIGURE 3 , 5A, 5F View FIGURE 5 ). Last branchiae smallest, digitate ( Figs 5A View FIGURE 5 , 6C View FIGURE 6 ).

Parapodia reduced anteriorly, with low conspicuous lobes. Parapodial lappets well developed in both noto- and neuropodia from chaetiger 15, continue to posterior chaetigers ( Figs 3C–D View FIGURE 3 , 4A, C View FIGURE 4 , 5A View FIGURE 5 ).

All chaetae spirally spinulose capillaries, emerging from deep depressions, present in all chaetigers ( Figs 5B–C View FIGURE 5 , 6A View FIGURE 6 ).

Oocytes present in two paratypes (SEM specimens), very small, about 2.5–3.6 µm in diameter ( Fig. 7A–B View FIGURE 7 ). Posterior end tapered; pygidium with anus terminal, with about 10 anal cirri of two types: six digitiform equal in size, and four short cirri, alternately arranged ( Figs 3C, E View FIGURE 3 , 6C–D View FIGURE 6 ).

Variation. In small specimens, the number of branchiae may be as few as 29–30 pairs because the posterior chaetigers and noto-and neuropodial lappets are large and cover all branchiae, making it difficult to see. Neuropodial pores are present only in holotype. Additional specimens are poorly preserved and branched branchiae start from chaetiger 2 and include 29–30 pairs.

Etymology. The specific epithet “ satunensis ” is derived from Satun, the name of the province of Thailand where the new species was collected.

Habitat. Fine mud mixed with fine sand, about 2–14 m depth, off the Andaman coast, in Southern Thailand.

Methyl green staining pattern. The tips of prostomium and branchiae are not stained. Epidermal papillae and pygidium are stained. Dark green color in anterior parapodia, lappets and large papillae of posterior chaetigers. In the pygidium, only the surface of the anal cirri is stained because of epidermal glands ( Fig. 3E View FIGURE 3 ).

Remarks. Travisia satunensis sp. nov. belongs to the subgroup having branched branchiae ( Table 2 View TABLE 2 ); T. satunensis sp. nov. most closely resembles T. arborifera Fauvel, 1932 from the Indian Ocean in having pectinate branchiae from chaetiger 2. However, T. satunensis sp. nov. has 10 anal cirri and they are in two alternating types (digitiform and short cirri), whereas T. arborifera which has 6–8 anal cirri, all short, as indicated in the key below.

In addition, the holotype of T. satunensis sp. nov. is 30.6 mm long and has 34 pairs of branchiae, absent from the last two chaetigers; whereas in T. arborifera with bodies up to 38 mm long, there are 29-30 pairs of branchiae, absent from the last 6–7 chaetigers ( Fauvel 1932).

On the other hand, T. satunensis sp. nov. differs from T. filamentosa de León-González, 1998 by having the first branchiae from chaetiger 2, nephridial pores along chaetigers 3 to 14, and pygidium with 10 anal cirri, whereas T. filamentosa has the first branchiae from chaetiger 3, nephridial pores are present along chaetigers 1–14, and its pygidium has 6 dorsal anal cirri, and lacks lateral cirri ( de León-González 1998).

Furthermore, at 30.6 mm long and 7.8 mm wide, the body of T. satunensis sp. nov. is smaller and shorter than the bodies of T. arborifera and T. filamentosa , which are respectively 38 mm long and 11–12 mm wide, and 68 mm long and 12 mm wide.

Distribution. Only known from Andaman Sea, Southern Thailand ( Fig. 1 View FIGURE 1 ).