Travisia, Johnston, 1840

Avery, Lynda, Vodopyanov, Stephan & Wilson, Robin S., 2023, New species of Travisia Johnston, 1840 (Annelida, Travisiidae Hartmann-Schröder, 1971) from south-eastern Australia, Memoirs of Museum Victoria (Mem. Mus. Vic.) 82, pp. 133-142 : 139

Travisia una sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:60C33D9B-979A-

41DB-A7A6-9E4F5736A8ED

Figures 8–15

Material examined. Holotype: Australia: Eastern Bass Strait , 15.5 km SW of Pt Ricardo, Stn MSL-EG 80, 37º 53.133' S, 148º 28.933' E, 4 Jan 1991, 45 m, NMV F271088 .

Paratypes: Australia: Victoria: Eastern Bass Strait , 7.3 km SSW of Cape Conran, Stn MSL-EG 116, 37º 52.65' S, 148º 42.15' E, Feb 1991, 49 m, 3, NMV F271081 - F271083 ; Eastern Bass Strait , 7.3 km SSW of Cape Conran, Stn MSL-EG 115, 37º 52.65' S, 148º 42.15' E, Feb 1991, 49 m, NMV F60672 ; Eastern Bass Strait , 7.3 km SSW of Cape Conran, Stn MSL-EG 116, 37º 52.65' S, 148º 42.15' E, Feb 1991, 49 m, 1, NMV F60673 ; Eastern Bass Strait , 15.5 km SW of Pt Ricardo, Stn MSL-EG 80, 37º 53.133' S, 148º 28.933' E, 4 Jun 1991, 45 m, 1, NMV F63841 ; Eastern Bass Strait , 2.9 km SE of Cape Conran, Stn MSL-EG 112, 37º 50' S, 148º 38.9' E, Feb 1991, 29 m, 1, NMV F200619 ; Eastern Bass Strait , 15.5 km SW of Pt Ricardo, Stn MSL-EG 80, 37º 53.133' S, 148º 28.933' E, 4 Jan 1991, 45 m, 1, AM W54587 .

Non-type material: Victoria: Western Port , WBES 1733 , 38° 23.0833' S 145° 27.3167' E, 29 Nov 1973, 10 m , 1, NMV F60031 .

Victoria: Eastern Bass Strait, 13.3 km E of eastern edge of Lake Tyers , Stn MSL-EG 67, 37º 51.7' S, 148º 14.6' E, 4 Jan 1991, 37 m, 1, NMV F60667 ; Eastern Bass Strait , 4.6 km S of Cape Conran, Stn MSL-EG 58, 37º 51.43' S, 148º 43.73' E, 28 Jan 1990, 50 m, 1, NMV F63838 ; Eastern Bass Strait , 7.3 km SSW of Cape Conran, Stn MSL-EG 117, 37º 52.65' S, 148º 42.15' E, Jan 1991, 49 m, 4, NMV F60674 ; Eastern Bass Strait , 7.3 km SSW of Cape Conran, Stn MSL-EG 61, 37º 52.667' S, 148º 42.067' E, 28 Jan 1990, 48 m, 5, NMV F63842 ; Eastern Bass Strait , 7.3 km SSW of Cape Conran, Stn MSL-EG 62, 37º 52.67' S, 148º 42.067' E, 28 Jan 1990, 48 m, 3, NMV F63837 ; Eastern Bass Strait , 7.3 km SSW of Cape Conran, Stn MSL-EG 88, 37º 52.65' S, 148º 42.15' E, 4 Jan 1991, 49 m, 5, NMV F60668 ; Eastern Bass Strait , 7.3 km SSW of Cape Conran, Stn MSL-EG 89, 37º 52.65' S, 148º 42.15' E, 4 Jan 1991, 49 m, 4, NMV F60669 ; Eastern Bass Strait , 7.3 km SSW of Cape Conran, Stn MSL-EG 90, 37º 52.65' S, 148º 42.15' E, 4 Jan 1991, 49 m, 4, NMV F60670 ; Eastern Bass Strait , Stn VC 41 A3, 37º 31.25' S, 148º 2.533' E, 8 Jan 1998, 10 m, 5, NMV F139260 ; Eastern Bass Strait , Stn VC 45 A1, 37º 28.3' S, 149º 2.567' E, 9 Jan 1998, 10 m, 1, NMV F139390 .

Diagnosis. Branchiae first present on chaetigers 3–6, 8–14 branchiate segments; all chaetigers uniannulate.

Description. Body comprising 20–25 segments; 19–24 chaetigers; 0–3 achaetous posterior segment(s), 3.6– 11 mm long, 1.5–3.6 mm maximum width at chaetiger 12; holotype 24 chaetigers, no achaetous posterior segments; 8.2 mm long, 2.3 mm maximum width at chaetiger 12. Body fusiform, evenly papillated, reaching greatest diameter chaetigers at chaetigers 15–20 (figs 8–11)

Prostomium longer than maximum width; a pointed cone (fig. 10) although often partially contracted. Mid-ventral groove absent. Peristomium undivided. Mouth located between chaetigers 1 and 2.

Chaetiger 1 and all subsequent chaetigers uniannulate without ridges; no posterior annulation pattern change. Branchiae present (but minute and difficult to observe); much shorter than body diameter; smooth. Branchiae first present on chaetiger 3–6; present on 8–14 chaetigers (8 in the holotype) and are longest in median chaetigers; number of posterior abranchiate segments: 3–8 (7 in the holotype).

Epidermal papillae forming a regular cover of raised polygons, each with 125–155 pores. Papillae width about equal to length (~60 µm) (width measured in circumferential direction around the worm, dimension y in fig. 15, length along the worm, dimension x in fig. 15). Parapodial lobes present; notopodial lobes commence chaetiger 15–17 (16 in the holotype); neuropodial lobes commence chaetiger 15–17 (16 in the holotype), present as prominent roughly triangular lappets over posterior-most 8–10 segments. Interramal pores when visible first present chaetiger 1, last present chaetiger 13–15 (not observable in the holotype). Nephridiopores first present chaetiger 3 (but not visible on many specimens including the holotype). Capillary chaetae smooth. Anal tube equal to length of 2 posterior segments. Pygidial lobes 9–22 (10 in the holotype), digitiform and unequal in width (figs 12, 13).

Staining pattern. Prostomium darkly stained uniformly with methylene blue (fig. 14), body, parapodial lobes and pygidial lobes uniform dark stain, only chaetigers 2 and 3 incompletely stained, branchiae unstained.

Remarks. Travisia una sp. nov. is readily recognised: it is the only species in the genus known in which all segments, both anterior and posterior, are without annulations. The presence of at most 14 pairs of branchiae commencing on chaetiger 3 or later and a short body of 19–24 chaetigers is also distinctive. Travisia una sp. nov. is also easily distinguished from the other known Australian species of Travisia : it is the only one with branchiae commencing on chaetiger 3 (all other Australian Travisia have branchiae first present on chaetiger 2), the only one with 14 or fewer pairs of branchiae (the others all have at least 23 pairs) and the only one with uniannulate segments throughout.

Etymology. The species name of Travisia una sp. nov. is taken from the Latin word for one, reflecting the segments of the new species, which comprise a single undivided annulus.

Distribution, ecology. South-eastern Australia: far-eastern Bass Strait. Depth range 10–50 metres.