Fimbrora calsubia Monniot & Monniot, 1991a

Hasegawa, Naohiro, Hookabe, Natsumi, Fujiwara, Yoshihiro, Jimi, Naoto & Kajihara, Hiroshi, 2024, Supplemental re-description of a deep-sea ascidian, Fimbrora calsubia (Ascidiacea, Enterogona), with an inference of its phylogenetic position, Zoosystematics and Evolution 100 (1), pp. 129-140 : 129

publication ID	https://dx.doi.org/10.3897/zse.100.113132
publication LSID	lsid:zoobank.org:pub:D84B5915-751E-4BAC-BB3A-A45E9282FE29
persistent identifier	https://treatment.plazi.org/id/0DCF6285-6710-5EF5-8A4B-80876FB60861
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Fimbrora calsubia Monniot & Monniot, 1991a
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Treatment

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Fimbrora calsubia Monniot & Monniot, 1991a, p. 384, figs 1-6; Monniot (1993), p. 356; Monniot and López-Legentil (2017), p. 531, figs 1, 2.

New Japanese name.

Yorifusa-boya, from yorifusa, an ornament for kimonos and Japanese accessories and boya, a phonological variant of hoya, meaning a sea squirt.

Material examined.

One individual, JAMSTEC No. 111618, collected by N. Hookabe on 26 September 2022, about 400 km off the Pacific coast of middle Honshu, Japan, 30°47.05'N, 138°44.72'E, at a depth of 2027 m (Fig. 1 View Figure 1 ) GoogleMaps .

Description.

Individual ca. 20 cm in length including oral siphon (Fig. 2A, B View Figure 2 ). Tunic opaque and gelatinous; blood vessels running on surface of tunic (Fig. 2B View Figure 2 ); fine warts, each about 0.5 mm in diameter, scattered evenly over entire tunic. Body attached to substrate with its posterior end (Fig. 2A, B View Figure 2 ). Oral siphon enlarged, ca. 10 cm in diameter; single annular muscle strand running on outer edge of oral siphon; thread-like lobes, 52 in number, tightly arranged to each other on oral-siphon edge; single groove radially arranged on edge of oral siphon between base of each lobe; muscle strand associated to each lobe, running on inner wall of oral-siphon edge from lobe base for ca. 1 cm; beneath inner surface of oral siphon, neural cords radially running from neural ganglion (Fig. 2C View Figure 2 ). Oral aperture situated 2.5 cm anterior to neural ganglion. Atrial siphon 1.5 cm in diameter; 37 blood vessels longitudinally running on surface of atrial siphon (Fig. 2D View Figure 2 ).

Body wall attached to tunic on oral siphon, heart and renal vesicles; irregular cavity existing between tunic and body wall; inner surface of tunic covered with epithelial tissue. Neural ganglion situated between oral siphon and atrial siphon. On base of oral siphon, 105 oral tentacles present, each being ca. 8 mm in length. Peripharyngeal band made of single lamina running in a short distance posterior to oral tentacles, forming V-shape posterior to neural gland aperture (Fig. 3A View Figure 3 ); latter being single in number, almost straight in shape (Fig. 3A View Figure 3 ) and opening at dorsal tubercle. Pharynx connected by mesenteries to peripharyngeal epithelium; mesenteries 0.5-3.0 mm in diameter (Fig. 3B View Figure 3 ). Smooth dorsal lamina running along mid-line on ventral side of pharynx (Fig. 3A, B View Figure 3 ). Longitudinal and transverse vessels running on inner surface of pharynx (Fig. 3C View Figure 3 ); 6-10 stigmata without lateral cilia per mesh (Fig. 3C View Figure 3 ). Secondary branchial papillae present on intersections of longitudinal and transverse vessels (Fig. 3C View Figure 3 ).

Digestive tract positioned on left side of body (Fig. 4A View Figure 4 ). Oesophagus opening to left side of dorso-posterior part of pharynx. Stomach about 1.5 cm in length, having 10 folds, surrounded with renal vesicles (Fig. 4A View Figure 4 ); multiple crustaceans (probably copepods) found in stomach lumen (Fig. 4B View Figure 4 ). Intestinal loop S-shaped, having primary loop and secondary loop; intestine ca. 7 cm in length, ca. 5 mm in diameter (Fig. 4A View Figure 4 ). Anus smoothly edged, opening close to atrial siphon (Fig. 4A View Figure 4 ).

Gonad situated proximally on intestinal loop (Fig. 4C View Figure 4 ). Ovaries surrounded with male testis (Fig. 4C, D View Figure 4 ). Oviduct and spermiduct running along secondary loop, opening close to anus (Fig. 4A View Figure 4 ). Eggs contained in ovaries and oviduct, up to 0.2 mm in diameter (Fig. 4D View Figure 4 ).

Habitat.

The animal attached itself to a dead sponge in an area with accumulated sand and mud at a depth of 2027 m, where the water temperature was 1.93 °C (Fig. 2A View Figure 2 ; Suppl. material 1). It opens the oral aperture in the direction facing the water current (Suppl. material 2). An euplectellid sponge was also found attached to the same substrate. Macrobenthos found around this area included other sponges, octocorals, sandy creeplets, sea anemones and sea lilies.