Oikopleura longicauda ( Vogt, 1854 )

Karunarathne, Krishan D. & Croos, M. D. S. T. De, 2021, Pelagic tunicates (Appendicularia and Thaliacea) of Sri Lanka: two first records with an annotated checklist, Zootaxa 5067 (3), pp. 352-376 : 356-357

Oikopleura longicauda ( Vogt, 1854)

Appendicularia longicauda Vogt 1854: 74 , Pl. 10 Figs. 4 –6.

Oikopleura spissa Fol 1872: 470–471 , Pl. 2 Fig. 8, Pl. 3 Figs. 1–4 . Lohmann 1896: 59.

Oikopleura (Coecaria) longicauda: Tokioka 1960: 354 .

Oikopleura longicauda: Lohmann 1896: 59 , Pls. 9, 10 Fig. 7. Bückmann 1969: 5, Fig. 8a–c. Fenaux 1993: 58, 71, 79; 1998: 300, 301. Aravena & Palma 2002: 312, Fig. 4A .

Material examined. Ten specimens ( MDAFWU 2020 /401–410), St.205, January 2020 .

Description. Trunk 1–1.5 mm long, compact. Strongly developed velum extending dorsally over the trunk. Mouth with a long lower lip without oral glands. Left lobe of the stomach with a small finger-shaped postcardial caecum directed upwards. Rectum extending slightly beyond the oral wall of the stomach. Gonads adjoining the coil of the gut, and embracing it laterally in mature individuals; the ovary is placed above the testis. Tail musculature broad and the subchordal cells absent.

Global distribution. The Antarctic Ocean, Atlantic Ocean, Indian Ocean, Pacific Ocean, the Mediterranean Sea and Red Sea ( Fenaux et al. 1998); Australian waters ( Thompson 1948). Type locality: off Nice, Mediterranean Sea.

Figures

FIGURE 1. Sampling localities of pelagic tunicates within the three regions of Sri Lankan Exclusive Economic Zone (EEZ) denoted by BBR (Bay of Bengal Region), LSR (Laccadive Sea Region) and IOR (Indian Ocean Region). Source of the map: Maritime Boundaries Geodatabase, Flanders Marine Institute (https://www.marineregions.org/). Remarks of each sampling station (St.) indicated by open circles are in Table 1

FIGURE 2. Firstly reported pelagic tunicates to Sri Lanka in “Waya-jel-Survey” (A–F): a live colony of Pyrostremma spinosum near to the sea surface (A & B), and an illustration of its blastozooid (C); Thalia sibogae solitary zooid in preserved form (D), ventral view of medioventral projections (E), and an illustration of its posterior part (F). a—anus; ap—atrial palp; dmp— dorsal medioventral projection; e—endostyle; es—excurrent/buccal siphon; g—ganglion; is—incurrent/atrial siphon; lp—lateral projection; n—nucleus; o—ovary; pb—pharyngeal basket; pp—posterior projection; sl—stolon; sm—stomach; t—testis; vmp—ventral medioventral projection. Scales: E = 0.5 mm; C, D, F = 1 mm; A & B = 0.4 m. Images A & B by Franco Banfi from off Mirissa, Sri Lanka

FIGURE 3. Re-reported salp, Pegea confoederata, to Sri Lanka in “Waya-jel-Survey” in preserved form (A–D): a colony of zooids (A); embryo (B); aggregate zooid (C); solitary zooid (D). E—endostyle; G—gill; N—nucleus; S—stolon. Scales: B = 5 mm; C & D = 8 mm; A = 20 mm.

FIGURE 4. Schematic diagrams of Sri Lankan pelagic tunicates, showing the general morphology of their families (A–H): the lateral view of mature individuals of Fritillariidae (A) and Oikopleuridae (B); gonozooid (C) and degenerated oozooid / nurse (D) of Doliolidae; dorsal view of a solitary zooid (E) and aggregate zooid (F) of Salpidae; a blastozooid (G) and sagittal section of a colony (H) of Pyrosomatidae. Adapted from Claus (1883), Esnal (1981), Barnes et al. (1993) and Sri Lankan specimens. Note: The tails of appendicularian diagrams have been rotated through 90º for clarity.