Tritoniella heideae, Schächinger & Schrödl & Wilson & Moles, 2022

Schächinger, Peter M., Schrödl, Michael, Wilson, Nerida G. & Moles, Juan, 2022, Crossing the polar front-Antarctic species discovery in the nudibranch genus Tritoniella (Gastropoda), Organisms Diversity & Evolution (New York, N. Y.) 22 (2), pp. 431-456 : 447-451

Tritoniella heideae n. sp.

( Figs. 6f , 16 , 17, S3)

Tritoniella sp. 5 Moles, Berning et al. (2021).

ZooBank registration urn:lsid:zoobank.org:act:95E0D612-CCE0-4C40-B7B9-66E6449E1FCC

Type locality Ardley Island , King George Island, Bransfield Strait, 62.2103° S 58.9139° W ; 20–40 m depth.

Diagnosis Colour translucent white to pink, central ridge straight, broad. Notum and notal margins covered with knobs. Jaws subquadrangular, spike subterminal. First lateral sometimes with median cusp, consecutive laterals with

◂ Fig. 15 Characteristic body parts of Tritoniella schoriesi n. sp. specimen ZSM 20110202–02 (paratype). A, jaws. B, scanning electron micrograph ( SEM) of the jaws showing masticatory border (mb) with a spike (sp). C , SEM of the radula showing rachidian (rh) teeth, first (fl) and subsequent (cl) lateral teeth. D, SEM of the radula showing lateral teeth. E, SEM of the penial papilla. F, SEM of the penial papilla showing tip (t). G, SEM of the gut content, showing sclerites. H, SEM of the gut content showing a spindle sclerite sharp tip, curved inwards. Vas deferens long, penial papilla elongated, tip pointed.

Material examined Ardley Island , King George Island, Bransfield Strait, 62.2103° S 58.9139° W, 20–40 m depth : 7

spcs., 2 dissected and 5 sequenced, ZSM 20141003 (paratype), L = 47 mm, W = 30 mm, H = 20 mm, COI barcode MW444366 , ZSM 20141004 (paratype), L = 53 mm, W = 34 mm, H = 21 mm, COI barcode MW444367 , ZSM 20141005 (paratype), L = 26–51 mm, W = 11–22 mm, H = 9–20 mm, COI barcode MW444368 , ZSM 20110221–06 (holotype), L = 51 mm, W = 33 mm, H = 22 mm, COI barcode MW444365 , ZSM 20110202–01 (paratype), L = 53 mm, W = 21 mm, H = 17 mm, COI barcode MW444364 . Montagu Island , South Sandwich Islands, 58.3773° S 26.2824° W, 153–420 m depth: 3 spcs., sequenced, SIO-BIC M12617A, L = 29 mm, W = 11 mm, ◂ Fig. 17 Characteristic body parts of Tritoniella heideae n. sp. specimen ZSM 20141005 B (paratype). A, jaws. B, scanning electron micrograph ( SEM) of the jaws showing masticatory border (mb) with a spike (sp). C , SEM of the radula showing rachidian (rh) teeth, first (fl) and subsequent (cl) lateral teeth. D, SEM of the radula showing lateral teeth. E, SEM of the penial papilla. F, SEM of the penial papilla showing tip (t). G, SEM of the gut content, showing sclerites. H, SEM of the gut content showing a gorgonian axis

H = 11 mm, COI barcode MW444359 , SIO-BIC M12617B, L = 24 mm, W = 12 mm, H = 7 mm, COI barcode MW444360 , SIO-BIC M12617C, L = 23 mm, W = 14 mm, H = 7 mm, COI barcode MW444361 ; 58.3845° S 26.2813° W, 147–262 m depth: 1 spc., sequenced, SIO-BIC M12608, L = 31 mm, W = 1 5 mm, H = 12 mm, COI barcode MW444357 ; 59.3936° S 27.3227° W, 110–188 m depth: 2 spcs., 1 sequenced, SIO-BIC M13011, L = 12–26 mm, W = 7–11 mm, H = 4–8 mm, COI barcode MW444363 . Bransfield Strait, 62.8695° S 57.2168° W, 150–247 m depth: 1 spc., sequenced, SIO-BIC M12593, L = 28 mm, W = 9 mm, H = 6 mm, COI barcode MW444356 ; 62.7529° S 57.3217° W, 272–292 m depth: 1 spc., sequenced, SIO-BIC M12615, L = 3 5 mm, W = 1 2 mm, H = 1 0 mm, COI barcode MW444358 ; 63.3228° S 59.8511° W, 197–199 m depth: 1 spc., sequenced, SIO-BIC M12581B, L = 31 mm, W = 18 mm, H = 11 mm, COI barcode MW444355 .

Etymology This species is dedicated to Heide Schulz for her research enthusiasm and merits in marine microbiology.

External morphology ( Fig. 16 ) Body 23–53 mm long, 9–34 mm wide, 6–21 high. Living specimens from transparent white, pink to light orange ( Fig. 16d ). Dorsal mantle surface with thick longitudinal central ridge, not reaching end of tail, straight; with knobs and tubercles, interspersed all over notum; one large tubercle or small head ridge central on head, not connected to central ridge. Central ridge, body margins, and knobs with white pigmentation (subepithelial). Notal margin with 5 to 7 extensions per side. Rhinophoral sheath large, extended laterally, connected to notal margin ( Fig. 16a ). Velum single-lobed, oral tentacles extended posterolaterally; velar margin with 9 to 14 short processes ( Fig. 16e ).

Jaws and radula (Figs. 17a–d, S3a–d) Jaws subquadrangular; amber in colour, masticatory border darker. Masticatory border short, coarse. Spike very coarse. Radular formula 55–64× 95–101.1.1.1.95–101. Rachidian tooth as long as broad; with lateral cusps on both sides of median cusp. First lateral tooth short, thick cusp, with lateral cusps on median side. Outer lateral teeth progressively hook-shaped, smooth; inner lateral teeth with sharp tip curved inward.

Male reproductive system ( Figs. 6f , 17e, f, S3e, f) Vas deferens very long, 17 folds. Penial papilla long, cone-shaped; with circular, broad enlargement close to tip; tip flat, cone-shaped.

Ecology Occurs at depths from 20–420 m (this study). Plates and spindle sclerites and inner axis of gorgonian present in the gut content of the dissected specimens, belonging to Primnoidae (Fig. 17g –h). Plate elongated squarish, oval or arrow-like, with dense tubercles on the inner side (Fig. 17g). Spindle spherical, rod-like (straight, curved, bi- or trifurcated) or irregular; tuberculated (Fig. 17g).

Distribution Bransfield Strait, Ardley Island (King George Island) and Montagu Island ( South Sandwich Islands) (this study); 20–420 m depth.

Remarks Tritoniella heideae n. sp. resembles most features of T. belli although it appears more slender, with a thinner, knob-interspersed notum.

Figures

Fig. 6 Schematic drawings of the male reproductive system showing vas deferens (vd) and penial papilla (pp). A, Tritoniella belli. B, T. gnocchi n. sp. C, T. prinzess n. sp., pp was attached to penial sheath

Fig. 16 Paratype of Tritoniella heideae n. sp. (ZSM 20110202–01). A, dorsal view. B, ventral view. C, lateral view. D, live picture. E, ventral view of the anterior part with velum