Travisia chinensis Grube, 1869

Yang, Deyuan, Wu, Xuwen, Wang, Zhi, Zhao, Xiaoyu, Hwang, Jiangshiou & Cai, Lizhe, 2022, Redescription of a rarely encountered species Travisa chinensis Grube, 1869 (Annelida, Travisiidae), including a description of a new species of Travisa from Amoy, China, ZooKeys 1128, pp. 1-17 : 1

Travisia chinensis Grube, 1869

Fig. 3A-C

Travisia chinensis Grube, 1869: 66; China Sea, North-western Pacific.

Travisia chinensis Augener, 1922: 38-40.

Diagnosis.

Body with 30 segments and 29 chaetigers. Branchiae cirriform from chaetiger 2, more than 25 pairs. Neuropodial lappet from chaetiger 16, notopodial lappet from chaetiger 19. Annulation pattern of segments: 1-15 triannulate, 16-26 biannulate, 26-30 uniannulate.

Material examined.

Holotype. ZMB 0629, Chinese waters ("Chinesische Gewässer”), Coll. GRUBE.

Description.

Body fusiform. Whitish in alcohol. About 30 mm in length (Fig. 3A ). Prostomium twisted, anteriorly pointed (Fig. 3B ). The mouth between chaetiger 1 and chaetiger 2 (Fig. 3B ). Branchiae cirriform, except one trifid present chaetiger 10 on the right side, more than 25 pairs, start on chaetigers 2 and to at least chaetigers 26 (Fig. 3A ). Most branchiae shorter than body width.

Chaetigers 1-15 without parapodial lappets. Chaetiger 16 with a small neuropodial lappet, below the bundle of neurochaetae on the right side of the body (Fig. 3C ). Notopodial lappet above the bundle of notochaetae starting on chaetiger 19. Notopodial and neuropodial lappets well developed from chaetiger 19, but missing on segments 29 and 30 (Fig. 3C ). Nephridial pores from chaetigers 3-14, the first four and last four small, the remainder larger (Fig. 3A ).

Neuropodial and notopodial chaetal rami well separated. Chaetae arising directly from body wall, with 29 chaetigers. All chaetae hair-like, smooth and without a fringe. Interramal pores from the first chaetigers segment to almost all segments except the last one segment. Segments 2-15 with three annulations, segments 16-26 with two annulations, last five segments with one annulation (Fig. 3A ). Pygidium as long as last three segments, with about 10 indentations.

Remark.

The original description of Travisia chinensis was not detailed. Thus, it was seldom compared with the other Travisia species. According to the original description, T. chinensis has one trifid branchia, while most other Travisia species have cirriform branchiae, except for T. arborifera Fauvel, 1932 from Indian Ocean and T. filamentosa León-González, 1998 from California which were reported with strongly branched branchiae. Some researchers accepted that the trifid branchia might make T. chinensis a distinctive species ( Kükenthal 1887; Fauvel 1932), while according to our observation, the trifid branchia is also present in a specimen of Travisia cf. pupa from the Yellow Sea (unpublished data), which is supposed to have only cirriform branchiae. Therefore, the presence of one bifid or trifid branchia might actually be an intraspecific variation and should not be regarded as a valid characteristic in distinguishing Travisia species.

Travisia chinensis (30 segments, 29 chaetigers) resembles the following six species in have a similar number of segments and chaetigers (29-31): Travisia amadoi Elías et al., 2003, Travisia olens Ehlers, 1897, Travisia araciae Rizzo & Salazar-Vallejo, 2020, Travisia hobsonae Santos, 1977, Travisia brevis Moore, 1923, and Travisia forbesii intermedia Annenkova, 1937.

Travisia chinensis differs in the start of parapodial lappets (chaetiger 19) from T. amadoi (chaetiger 12), T. araciae (chaetiger 13), and T. hobsonae (chaetiger 1). Travisia chinensis differs from T. brevis in the following morphological characters: the number of branchiae (>25 pairs in T. chinensis vs 22 pairs in T. brevis ); the shape of the prostomium (conical vs short blunt cone), and segments without parapodial lappets (last four segments vs last two segments).

Travisia forbesii intermedia and T. olens are not easily distinguished from T. chinensis more by lack of information. According to the original description, the former two lack exact data on the position of parapodial lappets, and a re-examination of the types of the two species is needed.

Type locality.

According to Salazar-Vallejo et al. (2014), the type locality was probably the coastal waters of Qingdao. Dauvin and Bellan (1994) also stated that the holotype was from the North-western Pacific. Until now, we have not found any other specimens of T. chinensis in the seas of China, based on the materials of MBM.

Figures

Figure 3. Travisia chinensis Grube, 1866 (holotype, ZMB 0629) A complete specimen in lateral view B anterior part in lateral view C posterior part in lateral view. Abbreviations: pr, prostomium; nuO, nuchal organ; mo, mouth; br, branchiae; chaet, chaetiger; IntP, interramal papilla; Pl, parapodia lateral lappet; np, nephridial pores; Py, pygidium.