ABSTRACT
Except for P. ferreri, the early life stages of the European paedomorphic species are relatively well-known. Th e eggs of A. minuta and C. linearis are demersal and very similar to those observed in Gobius, with a network of fi laments used to adhering to hard substrata, such as stones, shells or serpulid tubes (Raff ele, 1895; Grieg, 1896; Holt and Byrne, 1898; Lo Bianco, 1909; Clark, 1914; De Buen, 1931). Th e unfertilized eggs of A. minuta are slightly ovate with a wide perivitelline space, measuring about 0.8 mm (Iglesias, 1995), whereas those of C. linearis are club-shaped and approximately 1.5 × 0.5 mm (Raff ele, 1895; Grieg, 1896). The newly hatched larvae of A. minuta have been described only recently from specimens reared in aquarium (Lopez Jaime et al., 2000). The yolk-sac larva, measuring about 3-4 mm, is strongly pigmented with melanophores on the head, on the lower jaw and on the ventral abdominal contour. Two rows of melanophores, more scattered dorsally, form dorsal and ventral contours. The overall pigmentation is largely reduced with ontogeny. Th e postlarvae from 7 to 20 mm have the head totally unpigmented, some stellate melanophores on the ventral side of the abdomen, a typical dorsal pigmentation on the swimbladder and a postanal ventral row of melanophores, extending to the posterior end of anal fi n (Fig. 4.1.4a) (Ehrenbaum, 1905; Lebour, 1919; Petersen, 1919; Padoa, 1956; Russell, 1976). Th e second dorsal, the caudal and the anal fi ns are already developed at 7-8 mm of larval size. Th e fi rst dorsal fi n begins to develop at approximately 16-17 mm and it is not completely formed even at 20 mm length, when pectoral fi n rays appear. Th e postlarvae of A. minuta have been recorded off Plymouth and in the North Sea from June to September, with a main peak in July and August (Ehrenbaum, 1905; Clark, 1914; Allen, 1917). Th e newly hatched larva of C. linearis has not yet been described. Th e postlarva of 4-5 mm is strongly pigmented with melanophores on the head, in front of eyes, on the lower jaw and on the abdominal region. Th ere are also fi ve large evenly spaced melanophores along the dorsal contour and a continuous row from behind the pigmented swimbladder to the caudal fi n. Most of pigmentation disappears with ontogeny also in C. linearis, in particular in the dorsal region (Fig. 4.1.4b, c, d). Second dorsal and anal fi ns are fully developed at 9 mm, whereas pelvic and pectoral fi ns are beginning to develop at about 25 mm. The first dorsal fin, with only two rays, is present exclusively in males and develops later on (Fage, 1918; Lebour,
1919; Petersen, 1919; Padoa, 1956; Russell, 1976). Eggs and postlarvae of C. linearis were recorded in June and between May-October off Plymouth, respectively (Allen, 1917; Clark, 1920), and postlarvae 3.8 - 3.9 mm TL were caught in June in the Cantabrian Sea (Villegas, 1980). The early life stages of schindleriids have been reported exclusively for S. praematura and S. pietschmanni. Th e largest ovarian eggs lack oil droplets and are irregular in shape or oval, measuring 0.35-0.40 mm in S. pietschmanni and 0.30-0.65 in S. praematura (Watson et al.,1984). As seen previously in European species, the egg surface morphology in S. praematura is typical of gobies, being characterized by broad fi laments surrounding the micropyle (Johnson and Brothers, 1993; Th acker and Grier, 2005). Size at hatching is currently unknown for both species. However, S. pietschmanni at 1.9 mm has a rather large yolk-sac. Notochord fl exion occurs between 2.7-3.5 mm in S. pietschmanni and before 4.3 mm in S. praematura (Watson et al.,1984; Watson, 2000). Th e larval pigmentation is very similar in both species, being characterized by one to four pairs of melanophores along the side of the gut, one to four melanophores along the ventral midline of the caudal fi n and pigment on the posterior dorsal surface of the swimbladder (Fig. 4.1.4e). Except for the swimbladder, all the pigment is lost during the juvenile stage. Dorsal and anal fi n rays are the fi rst to develop, followed by the pectoral fi n rays (Ozawa and Matsui, 1979; Sardou, 1974; Watson et al.,1984; Watson, 2000). Typically, the early life stages of Schindleria occur inside coral-reefs lagoons, where they complete all the larval development (Leis, 1982, 1994; Leis et al., 2003). The morphogenesis of early life stages of L. petersii, including the embryonic development from egg fertilization to larval hatching, has been recently described by several authors under rearing condition (Nakatsuji et al.,1997; Arakawa et al.,1999; Kitano, 2002; Saito et al., 2001, 2002). Th e chorion of unfertilized eggs is round and close to the egg surface, with a wide perivitelline space and a tuft of fi laments near the animal pole used for attachment to the underside of rocks. Hatching occurs between 10-18 days aft er egg fertilization, and the newly hatched larva as long as 4.3 mm is completely transparent (Matsui, 1986; Arakawa et al.,1999; Arai, 2006). Yolk absorption in early larvae occurs at 6-7 mm TL. Dorsal, anal and pectoral fi ns are fully developed at 10.0-12.5 mm TL, whereas pelvic fi ns are completed at 37-38 mm TL (Fig. 4.1.4f, g, h) (Matsui, 1986). Larval stages of L. petersii occur between June-August in Otsuchi Bay (northeastern Japan) (Yamashita and Aoyama, 1984).
