Том 56, № 4 (2016)

Two species, M. danae Ebeling and M. pumilis Ebeling, belonging to the species group “M. simus” are described in the final part of the revision of oligo-raker species of the genus Melamphaes (Melamphaidae) (≤19 gill rakers on the first gill arch). The species M. danae is distributed in the Indian and Pacific oceans between 30° N and 30° S. In the Pacific Ocean, it is known up to 112° W. The species M. pumilis is distributed in the North Atlantic between 17° and 45° N, and the main catches have been conducted in the western part of the ocean. In the eastern part of the ocean, the catches are registered up to 28° W. A key for the identification of 21 oligo-raker species of the genus Melamphaes is presented.

After performing principal component analysis (PCA) of 13 characters (indices) of skulls of large African barbs (Barbus intermedius complex sensu Banister, 1973) from Lakes Awasa and Langano (Ethiopia) distributions of individuals in coordinates BL and PC1 were studied where BL is the basal skull length and PC1 is the first principal component. It is shown that in both the lakes there are groups of barbs whose individual ontogenetic trajectories are situated within separated ontogenetic channels. Separation of the channels is by far less distinct than that of the channels of generalized and specialized forms of barbs from Lake Tana and not correlated with differences in external traits. It is suggested that the revealed polymorphism is connected with food resource partitioning and might serve as a prerequisite of further divergence of sympatric forms of large African barbs.

Illustrated descriptions of the larval and/or juvenile fish of the following scarcely studied taxonomic forms are given: Tiluropsis (Halosauridae), Heteroconger sp. (Heterocongrinae), Lampanyctus alatus, Lampanyctus cf. crocodilus, Lampanyctus sp. 1, Loweina rara, Myctophum affine (Myctophidae), and Bregmaceros atlanticus (Bregmacerotidae). The problems of identifying of early development stages of these taxa are considered.

Based on the analysis of variability of mitochondrial and nuclear DNA and calibration of the molecular clock using the paleontological data, the divergence time of the eelpouts is assessed. The temporal frames of the evolution of the suborder Zoarcoidei are restricted to the Late Oligocene and the middle of the Late Miocene, within a diapason of approximately 12 Ma. The families Bathymasteridae and Cebidichthyidae were the first to separate from the common ancestor, 14.7–22.5 and 13.1–19.1 Ma, respectively. The differentiation of other families occurred between the Middle and the Late Miocene approximately 10–15 Ma. The period from the Late Miocene to the Mid-Pliocene (3.6–7.8 Ma), most likely, was the time of the appearance and distribution of the present species of the suborder. Assessment of the DNA divergence rate in the eelpouts conducted in this study is in accordance with known evolutionary scenarios and with key steps of geological development of the World Ocean.

To estimate reproductive biology of Ponticola iranicus Vasil’eva et al., 2015, in Sefidroud River in the southern Caspian Sea basin age, sex ratio, fecundity, oocytes diameter, gonadosomatic, modified gonadosomatic and dobriyal indices were measured. Regression analyses were used to find relations between fecundity and fish size (length and weight), gonad weight, and age. Mature females and males were longer than 46 and 49 mm in total length, +1 in age. The Von Bertalanffy growth models were L_∞ = 23.00 cm (TL), K = 0.21, t₀ =–0.25 for all specimens. Sex ratio was 1: 1.32 in favor of males. The average egg diameter was 0.96 mm. The spawning period extended from late February to late April. The averages of absolute and relative fecundity were calculated as 536.9 and 81.3, respectively. The absolute fecundity was significantly related to the body length and weight, as well as gonad weight.

The species Upeneus margarethae described recently from the western Indian Ocean is recorded in the coastal zone of Vietnam for the first time. The reproductive features of the representatives of the species from southern Central Vietnam (Nha Trang Bay), Central Vietnam (Da Nang), and North Vietnam (Ha Long Bay) are studied. Based on the analysis of maturity stages of female’s ovaries and gonadosomatic index, the fishes spawn over the entire year in Central Vietnam, but the spawning interruption is observed in North Vietnam during a winter season. In Nha Trang Bay, 50% of females reach sexual maturity at the body length (FL) 9.8 cm. Based on histological structure of ovaries and frequency distribution of oocyte diameter before the spawning, the oogenesis is continuous. Anomalous oocyte structure is registered in 20% of the females. Egg morphology is described for 3 h after activation of ovulated oocytes. A comparison of reproductive parameters in U. margarethae and U. tragula is conducted.

Photonectes venetaenia sp. n., which differs from the closely related species by the pattern of blue luminous tissue on the body, the barbel with a short stem but a long filament, and other traits, was described from the equatorial waters of the western Pacific Ocean.

The record of bluemouth rockfish Helicolenus dactylopterus (Delaroche, 1809) at low depth suggests that the species is prone to large vertical migrations. This capture confirms the occurrence of the species in the Tunisian waters where it is known as very rare. It confirms also the success of ecological restoration of Tunis Southern Lagoon and the possible establishment of fish populations, mainly due to a favourable biological environment, mostly constituted by crustacean species among them, species belonging to the genus Sphaeroma Latreille, 1802 play an important role.