Aplidium lobatum Savigny, 1816

Rocha, Rosana Moreira Da, Gamba, Gustavo Antunes & Zanata, Thais Bastos, 2012, Aplidium (Ascidiacea, Polyclinidae) in central coast, Brazil, Zootaxa 3565, pp. 18-30 : 23-25

Aplidium lobatum Savigny, 1816

( Figure 4 , 6 D, 7A)

Aplidium africanum Sluiter, 1905a: 17 , pr. 2, fig. 9, Djibouti, Gulf of Tadjourah (Red Sea). Aplidium lobatum Van Name, 1921: 303 , fig. 3, Puerto Rico and West Indies; Van Name, 1930: 425, fig. 4, the Caribbean; Plough & Jones, 1937: 100, Florida; Van Name, 1945: 28, fig. 3, the Antilles and Puerto Rico; Monniot & Monniot, 1984: 571, Guadeloupe.

Aplidium quinquesulcatum Millar, 1977: 91 , fig. 17, Brazil.

Material examined: DZUP POCL- 28 1 colony, Forte São Marcelo, Salvador, Bahia, 12°58'13"S, 38°31'03"W, 5 m, Col. R. M. Rocha, 01.08.1999; DZUP POCL- 30 1 colony, Pedra Verde, Salvador, Bahia, 12°57'52"S, 38°30'57"W, 23 m, Col. E. M. Hajdu, 07.08.1999; DZUP APL- 04 1 colony, Porto da Barra, Salvador, Bahia, 13°00'37"S, 38°31'41"W, 5 m, Col. R. M. Rocha, 0 6.06.2004.

Colonies are encrusting, to 12 cm in diameter, 3−5 mm thick, cushion-shaped, but may form lobes. Consistency is reminiscent of cartilage. The smooth surface has rounded elevations. Color varies from brick to wine when alive ( Fig. 6 D) which fades to brownish when preserved. Zooids form elongated systems, sometimes branched, along the cloacal channels. The tunic contains sand.

Zooids are 5–6 mm long, thorax 2−3 mm, abdomen 2 mm, and the post-abdomen 1 mm long. Zooids are transparent light yellow. The oral siphon has six elongate, triangular and pointed lobes. The circular opening of the atrial siphon is wide and bordered by circular muscle fibers, between the second and fifth row of stigmata (if viewed when zooids are well relaxed). The atrial languet is short and wide with three long and narrow projections at the distal margin. The longitudinal musculature is delicate, with eight fibers on each side of the thorax, extending from the base of the oral siphon to the end of the post-abdomen.

The pharynx has 8−9 rows of stigmata with 10–15 stigmata per row on each side. Approximately 16 oral tentacles are of two sizes. The esophagus is long and narrow. The stomach is short with five well defined and continuous longitudinal folds. The duodenum is narrow and short (length equal to about half that of the stomach), followed by a constriction and by the posterior stomach, expanded and in the intestinal loop. The ascending intestine is long and wide with a long and narrow rectal caeca. The anus is smooth and opens between the fifth and sixth rows of stigmata ( Fig. 4 ).

The ovary has 2–4 oocytes. The testis comprises 14−16 grouped spherical or oval follicles; the sperm duct opens alongside the anus. Three colonies (two females, one male) were collected ( Fig. 4 ). Larvae are elongated, trunk length is about 0.8 mm. Ocellus and otolith are in the posterior region. The pharynx has two rows of stigmata. Three adhesive papillae are equidistant, bell-shaped and supported by short and narrow stalks. About 75 ectodermal vesicles are in the anterior, ventral and dorsal surface of the larva. The tail is on the same plane as the adhesive papillae and winds around ¾ of the larva ( Fig. 4 C, 7A). Between one and three larvae are incubated in the atrial cavity.

Remarks. The original description of A. lobatum Savigny (1816) is brief and did not include larvae. Nonetheless, colony and zooid characteristics are very similar to those of our samples, except for the smaller number of rows of stigmata in the Brazilian specimens. Caribbean specimens are very similar to those from Brazil ( Van Name 1921, 1945), except for the oral siphon with bifid lobes and the pharynx with seven rows of stigmata in zooids in the Caribbean. Zooids from Guadeloupe are also very similar ( Monniot & Monniot 1984) and even have a long and narrow rectal caeca as observed in Brazilian specimens. But the thorax there is red in life which was not seen in Brazilian specimens.

Aplidium quinquesulcatum , which was reported only in northern and northeastern Brazil, has a flattened colony encrusted with sand, zooids have eight or nine rows of stigmata, stomach with five longitudinal folds and a short post-abdomen. According to Millar (1977), these features distinguish this species from all other reported for the western north and south Atlantic, but he did not compare his samples with A. lobatum initially described for the Gulf of Suez. Both descriptions are very similar, leaving no doubt that these are the same species. The name A. lobatum has precedence and should be used.

In the description of A. macrolobatum , a new species in the Pacific, Kott (1992) used the material she reported in 1963 as A. lobatum . She based the differences between A. macrolobatum and A. lobatum only in the organization of zooids and the presence of depressions in the surface of colony. Moreover, Kott (1992) also included previous records of A. lobatum (Tokioka 1967; Nishikawa 1984; Monniot 1987; Monniot & Monniot 1987) with the species A. ritteri ( Sluiter, 1895) . Therefore, we believe that the three species A. lobatum , A. macrolobatum and A. ritteri require an extensive and detailed review to define their status. Currently, because of the wide geographical distribution of A. lobatum , we classify it as cryptogenic in Brazil.

Figures

FIGURE 4. Aplidium lobatum. A, zooid with female gonad. B, zooid with male gonad. C, larva. Scales: A, B: 1 mm, C: 0.5 mm.

FIGURE 6. A, Aplidium antillense at shipwreck Reliance, Salvador, Bahia. B, Aplidium elongatum below two colonies of Didemnum psammatodes (Sluiter, 1895), Island Pacotes, Vila Velha, Espírito Santo. C, Aplidium elongatum in cross section. D, Aplidium lobatum at Praia da Barra, Salvador, Bahia. E, F, Aplidium selenium at Quebramar norte, Salvador, Bahia.