Squalus shiraii sp. nov. (Squaliformes, Squalidae), a new species of dogfish shark from Japan with regional nominal species revisited

A new species of deep-water dogfish shark, Squalus shiraiisp. nov., is described herein as endemic to the tropical waters off Southern Japan. This species has been largely misidentified with S. mitsukurii. However, morphological, meristic and morphometric evidence support it to be a separate and undescribed species. Squalus shiraiisp. nov. differs from this species by having body brown in colour dorsally, caudal fin with ventral and dorsal tips markedly tapered and broadly white, dermal denticles uniscuspidate and lanceolate and larger number of precaudal (91–94) and total vertebrae (120–123) (vs. body dark grey to black; caudal fin with ventral and dorsal tips rounded and not white in colour; denticles tricuspidate and rhomboid; 86–90 precaudal and 116–117 total vertebrae). Squalus shiraiisp. nov. is also clearly separated from other Japanese congeners which are herein revisited to include six species, based on the examination of over 150 specimens caught from Japanese waters that were available in ichthyological collections: S. mitsukurii, S. japonicus, S. acutirostris, S. brevirostris and S. suckleyi. Squalus mitsukurii, S. japonicus and S. brevirostris are re-described in detail and the neotype of S. japonicus is herein designated. Squalus acutirostris is treated as a valid species with occurrences in Japan, China and Taiwan and, thus, a provisional diagnosis is given, as well as an updated diagnosis of S. suckleyi. A key to Squalus species from the North-western Pacific Ocean is given and main morphological differences between S. shiraiisp. nov. and the closest related species are discussed.

New spectral templates for rhodopsin and porphyropsin visual pigments

A four-parameter model of spectral sensitivity curves was developed. Empirical equations were designed for A1- and A2-based visual pigments with the main ?-band maximum absorptions (?max) from 350 nm, near the ultraviolet, up to 635 nm in the far-red part of the spectrum. Subtraction of the ?-band from the full absorbance spectrum left a ??-band? described by a ?max-dependent Gaussian equation. Compatibility of our templates with A1- and A2-based spectra was tested on the electroretinographic (ERG-derived) scotopic action spectra recorded in dogfish shark, eel, Prussian carp and perch. To more precisely estimate the accuracy of our model, we compared it with widely used templates for visual pigments. There was almost no difference between the tested models in fitting the above-mentioned spectral data. One of the advantages of our model is that in the fitting of spectral sensitivity data it uses non-transformed wavelengths and the shape of the curve remains the same for a broad range of ?max values. Compared to multiparameter templates of other authors, our model was designed with fewer (four) parameters, which we believe can bring us closer to understanding the true nature of the absorption curve.

Description of a new deep-water dogfish shark from Hawaii, with comments on the Squalus mitsukurii species complex in the West Pacific

Dogfish sharks of the genusSqualusare small, deep-water sharks with a slow rate of molecular evolution that has led to their designation as a series of species complexes, with low between-species diversity relative to other taxa. The largest of these complexes is named for the Shortspine spurdog (SqualusmitsukuriiJordan & Snyder), a medium-sized dogfish shark common to warm upper slope and seamount habitats, with a putative circumglobal distribution that has come under investigation recently due to geographic variation in morphology and genetic diversity. The Hawaiian population ofSqualusmitsukuriiwas examined using both morphological and molecular analyses, putting this group in an evolutionary context with animals from the type population in Japan and closely-related congeners. External morphology differs significantly between the Hawaiian and JapaneseS.mitsukurii, especially in dorsal fin size and relative interdorsal length, and molecular analysis of 1,311 base pairs of the mitochondrial genes ND2 and COI show significant, species-level divergence on par with other taxonomic studies of this genus. The dogfish shark in Hawaii represents a new species in the genus, and the nameSqualushawaiiensis, the Hawaiian spurdog, is designated after the type location.

Squalus clarkae sp. nov., a new dogfish shark from the Northwest Atlantic and Gulf of Mexico, with comments on the Squalus mitsukurii species complex

Sharks of the genus Squalus have slow reproductive rates coupled with low genetic diversity, as is typical of deep-water sharks, making this group slow to rebound from depletion due to overfishing. The number of species within Squalus has been expanding recently due to increased attention on taxonomic revision, and a growing research focus on little-known deep-water sharks in general. Here we use genetics and morphology to describe a new species of dogfish shark, Squalus clarkae sp. nov. from the Gulf of Mexico (GoM) which replaces Squalus mitsukurii in this region, and place it in the context of congeners from the Atlantic and elsewhere. Previously, S. clarkae sp. nov. was considered a part of the Squalus mitsukurii species complex, a group of closely related but distinct species. We sequenced the mitochondrial cytochrome oxidase I and the NADH Dehydrogenase II gene of S. mitsukurii from the type location in Japan, S. clarkae sp. nov. from the GoM, as well as three closely related species (S. cubensis, S. blainville, and S. megalops) and S. cf. mitsukurii from Brazil. Squalus clarkae sp. nov. is genetically distinct from other species with significant statistical support (>98.6% bootstrap support/posterior probability), and 2.8% divergent from S. mitsukurii in the type location of Japan. Morphological estimates also revealed differences between S. clarkae sp. nov., S. mitsukurii, and other Atlantic Squalus species, with S. clarkae sp. nov. exhibiting a longer body, smaller interorbital space, shorter caudal fin, and a differently-proportioned first dorsal fin. In general, dogfish sharks in the Atlantic and GoM are characterized by similar but distinct morphology, significant genetic variation, and small species ranges.

KOMPOSISI HASIL TANGKAPAN DAN DAERAH PENANGKAPAN HIU BOTOL (Centrophoridae) YANG DIDARATKAN DI TENAU, NUSA TENGARA TIMUR

Hiu botol merupakan jenis ikan hiu yang bernilai ekonomis tinggi, karena dapat menghasilkan minyak ikan dari ekstrak hati dinamakan squalen. Pada umumnya, hiu botol hidup di perairan Samudera Hindia pada kedalaman lebih dari 100 meter, namun sampai saat ini penyebarannya belum banyak diketahui. Selain itu, informasi terkait komposisi jenisnya masih sangat terbatas. Tulisan ini bertujuan mengkaji komposisi hiu botol yang tertangkap rawai dasar dan daerah penangkapannya di perairan Samudera Hindia yang berbasis di Kupang, Nusa Tenggara Timur. Data diperoleh dari survei lapangan dan wawancara dengan nelayan penangkap hiu di daerah Tenau, periode bulan Januari-Desember 2016. Hasil kajian menunjukkan bahwa hiu botol yang menjadi target penangkapan terdiri atas tiga jenis yaitu; Centrophorus squamosus (10-13%), Centrophorus granulosus (15-20%), dan Centroscymnus coelolepis (sekitar 40%). Prosentase hiu botol yang di Samudera Hindia berkisar 0,01-0,04 % dari total tangkapan yang didaratkan di Pelabuhan Perikanan Pantai Tenau. Sedangkan, prosentase hiu botol periode tahun 2011-2014 relatif besar dibandingkan dengan hasil tangkapan jenis hiu lainnya. Namun, pada periode 2012-2014 hasil tangkapan hiu botol cukup fluktuatif dan cenderung menurun. Hal ini mengindikasikan bahwa populasi sumber daya jenis hiu ini telah terjadi penurunan. Hasil tangkapan hiu botol tertinggi terjadi pada bulan Januari-Februari dan Agustus-September, yang tertangkap di wilayah perairan Selatan Pulau Rote, Timor dan Sabu. Daerah penangkapan potensial hiu botol berada pada koordinat 1240-1280 BT dan 100-110 LS pada kedalaman antara 200-800 meter. A dogfish shark has a high economic value, especially its liver oil, namely squalen. In general, a dogfish sharks live in the waters of the Indian Ocean at a depth of over 100 meters, but its distribution and composition has not been well documented. This paper aims to describe the composition of sharks caught by bottom longlines operated in the Indian Ocean landed at Kupang, East Nusa Tenggara. Data obtained from field surveys and interviews with shark fishermen from Tenau in January-December 2016. The results showed that the dogfish shark consisted of three species: Centrophorus granulosus, Centrophorus squamosus and Centroscymnus coelolepis. The percentage of dogfish sharks in the Indian Ocean ranged from 0.01 to 0.04% of the total catch landed at Tenau. While the percentage of dogfish shark in period 2011 - 2014 was relatively large compared to the catch of other species of sharks. However, in period 2012 - 2014 dogfih shark catches fluctuated and tended to decrease. This indicates that the population decline of this species. The highest catches of dogfish shark occurred in January-February. During August-September sharks were caught in the territorial waters of the South Island of Rote, Timor and Sabu. Potentially fishing areas of dogfish shark would be located at 124o-128o E and 10o-11o S with depths between 200-800 meters.

ASPEK BIOLOGI DAN DAERAH PENANGKAPAN CUCUT BOTOL (Squalus sp.) YANG TERTANGKAP DI PERAIRAN SAMUDERA HINDIA

Penelitian mengenai keragaman jenis Elasmobranchi dilakukan pada bulan Januari sampai dengan Desember 2002 di pelabuhan-pelabuhan perikanan PPI Cilacap, TPI Palabuhanratu, TPI Kedonganan-Bali, dan PPI Tanjung Luar-Lombok Timur. Cucut botol Squalus sp. merupakan jenis cucut laut dalam yang paling sering dijumpai selama penelitian berlangsung. Hasil penelitian menunjukkan bahwa cucut botol betina lebih sering tertangkap dibandingkan cucut jantan pada setiap waktu pengamatan. Frekuensi panjang cucut botol tertinggi dijumpai pada bulan Juni danAgustus yaitu berkisar antara 62 sampai dengan 68 cm. Nisbah kelamin cucut botol antara jantan betina selama pengamatan adalah 1:1,83. Hubungan antara panjang total tubuh dan panjang klasper cenderung linier dengan nilai R2=0,634326. Puncak musim penangkapan cucut botol terjadi sekitar bulan Agustus. Sedangkan daerah penangkapan cucut botol adalah di perairan Samudera Hindia. A study on diversity Elasmobranchi of was conducted using market surveys method from January to December 2002 at several fish landings in southern Indonesia, i.e. the Cilacap, Palabuhanratu, Kedonganan- Bali, and Tanjung Luar-East Lombok landing sites.A deep water shark, Indonesian shortnose spurdog (Squalus sp.), was the most common deep water sharks captured in the area during the study. Results show that females sharks were caught more frequent at every observation than those of males. The most abundant of Indonesian shortnose spurdog was recorded in June and August ranging from 62 to 68 cm in total length. Sex ratio between males and females of Squalus sp. during the study was 1:1.83, and the relationship between total length and claspers length of dogfish shark was linier (R2=0.634326). The peak fishing season of Indonesian spurdog was occurred in August with the fishing area was in the Indian Ocean.