aqua International Journal 17(1)
Volume 17, Issue 1 – 15 January 2011
Volume 17, Issue 1 – 15 January 2011
José I. Castro: Resurrection of the name Carcharhinus cerdale, a species different from Carcharhinus porosus, pp. 1-10.
The smalltail shark, Carcharhinus porosus Ranzani, 1840, is a small shark that inhabits the western North Atlantic Ocean from the Gulf of Mexico to Brazil. Carcharhinus cerdale Gilbert, in Jordan and Evermann, 1898, is a small shark that inhabits the eastern Pacific from the Gulf of California to the tropics. Through a series of mistakes these two allopatric species were synonymized. Meek & Hildebrand (1923) probably committed the first error when they misidentified or assumed the origin of market specimens in Colón, Panama, and stated that C. cerdale was found in both sides of the Isthmus of Panama. Meek & Hildebrand did not compare C. cerdale with C. porosus, and they did not synonymize the two species. Bigelow & Schroeder (1948) made the second error by stating that Meek & Hildebrand had synonymized C. cerdale and C. porosus. Their publication was so authoritative that the synonymy would not be challenged by most workers for more than 60 years, although Kato et al. (1967) were aware that C. cerdale was different from the Atlantic C. porosus. The name Carcharhinus cerdale Gilbert, in Jordan & Evermann, 1898, is resurrected here for the Pacific species.
Marcela Bejarano-Álvarez, Felipe Galván-Magaña and Rosa Isabel Ochoa-Báez: Reproductive biology of the scalloped hammerhead shark Sphyrna lewini (Chondrichthyes: Sphyrnidae) off south-west Mexico, pp. 11-22
The scalloped hammerhead shark Sphyrna lewini is the most important species in the artisanal shark fishery in the Gulf of Tehuantepec, Mexico. Knowledge about the reproductive biology of this species in the area is nonexistent, despite its being listed worldwide as endangered by the IUCN. To determine the basic reproductive biology of this shark would give important data for management or conservation plans for this species in Mexico. Samples were collected of 991 hammerhead sharks (342 females and 649 males), including juveniles (45 to 160 cm TL) and adults (170 to 288 cm TL), from September 2004 to June 2006. The sex ratio was 1F: 2M. The scalloped hammerhead was present year round in the study area with the greatest catch from May to July, the season when pregnant females were present. The females reached sexual maturity at 220 cm TL based on characteristics and measurements of reproductive organs. A histological analysis showed that testes in males are a diametric type and have compound spermatozeugmata in the seminal vesicles, indicating sexual maturity in males at 180 cm TL. We recorded 40 pregnant females, with 14 to 40 embryos per female. The births occurred in July and August with an embryo size of between 41 and 51 cm TL. The presence of neonates, juveniles, and pregnant females with embryos in an advanced development condition suggest that the coastal waters off Oaxaca are an important nursery area for the scalloped hammerhead shark.
Eugenie Clark and John E. Randall: Cephaloscyllium stevensi: a new species of swellshark (Carcharhiniformes: Scyliorhinidae) from Papua New Guinea, pp. 23-34
Cephaloscyllium stevensi n. sp., is described from five adult specimens (445-660 mm TL) taken in a Nautilus trap set in 240-274 m off eastern Papua New Guinea. It is distinguished from its similar congener, C. speccum Last, Séret & White, from off north-western Australia, by its color pattern: gray-brown above and lighter ventrally. The entire body is mottled with brown and whitish spots of variable size; there are six large dorsal dark brown saddle blotches on the head and body and three on the caudal fin; the anterior four dorsal blotches connect or lead obliquely to other dark blotches ventrally; and the small white spots are larger in males than females and are most distinct within or at the edges of the dark brown blotches. The dense mottling of brown and white spots ventrally on the head and body appears unique to this species. A mature female (660 mm TL) had 16 large yellow oocytes (8-21 mm diameter). The proximal half of the claspers of the two adult male paratypes have a closed tube, as has been described for two other benthic sharks in the genera Ginglymostoma and Halaelurus.
Gerald R. Allen, Mark V. Erdmann and Vincent V. Hiloman: A new species of damselfish (Pomacentrus: Pomacentridae) from Brunei and the Philippines, pp. 35-42
Pomacentrus cheraphilus n. sp. is described from 19 specimens, 48.7-61.0 mm SL, collected at Brunei and northern Palawan, Philippines. It is distinguished from most similar species in the western Pacific by a combination of characters that include XIII dorsal spines, 13-14 soft dorsal rays, 13-15 soft anal rays, 17-18 pectoral rays, 17-19 tubed lateral-line scales, 19-21 total gill rakers on the first branchial arch, a yellow juvenile phase with blue stripes on the upper head and adjacent anterodorsal portion of the body, and light grey to dark greyish brown adult phase with a dark-edged greenish spot just below lateral line origin. The new species inhabits silty reefs around coral and rock outcrops at depths of 10-18 m.
Walter Ivantsoff and Gerald R. Allen: A new species and genus of a large and unusual freshwater hardyhead, Sashatherina giganteus (Pisces: Atherinidae) from West Papua, Indonesia and a comparison with its closest relatives of the genus Craterocephalus, pp. 43-57
Over the last several decades it has become possible to collect in western New Guinea, now known as the Indonesian province of West Papua. Two collectors, Heiko Bleher and the second author, have collected at different times and brought back, amongst other species, some unusual specimens of a large hardyhead from Lake Lakamora (part of Triton Lakes complex, sometimes also known as Lake Laamora, at 3°41’S 134°17’E). The largest collected specimen of Sashatherina giganteus n. gen. n. sp. was measured to be 180 mm TL (total length) which far exceeds the largest known Old World species (eg. Atherinomorus species) and unconfirmed reports suggest that these fish may grow as large as 350 mm TL. This “giant” hardyhead is also unique in several other characters: it has very numerous small scales with a maximum midlateral scale count of 60 and up to 17 rows of transverse scales. Although there is usually a high correlation between the midlateral scale count and the number of vertebrae, this is not the case in this species. All of the scales are crenulated, another unique feature of this new genus. The lower jaw is very pronounced and protruding beyond the anterior border of the premaxilla. The shape of the pectoral girdle is also different to other known species. The eye in this species is quite small. Sashatherina giganteus n. gen. n. sp. is closely related to the genus Craterocephalus on the basis of osteological comparison. The genus Craterocephalus is represented by 6 species in New Guinea and by 18 species and one subspecies in Australia, in freshwater, estuarine and marine environments. One species, C. laisapi, is also found in East Timor. Sashatherina n. gen., on present knowledge, is monotypic and distinct on the basis of characters described.
|Dimensions||26.6 x 20.3 x 0.3 cm|
|print or online||