A new sisorid catfish of the genus Pseudolaguvia (Teleostei: Sisoridae) from Nagaland, north-eastern India

Pseudolaguvia vespa, new species, is described from the Tsücha River, Mokokchung district, Nagaland, India. The new species can be distinguished from congeners in having the following combination of characters: length of dorsal-fin spine 12.3–16.8% SL, a smooth anterior edge of the dorsal-fin spine, caudal peduncle depth 9.0–10.5% SL, body depth at anus 15.6–17.7% SL, caudal fin length 20.7–24.5% SL, pectoral fin length 20.1–24.1% SL, interorbital distance 22.7–28.1% SL, thoracic adhesive apparatus extending to midway between base of last pectoral-fin ray and pelvic-fin origin, and live specimens with two irregular, chrome-yellow bands on the body.

Fish morphology and passage through velocity barriers. Experience with northern straight-mouth nase (Pseudochondrostoma duriense Coelho, 1985) in an open channel flume

Knowing the relationship between size, morphological traits and swimming performance of fish is essential to understand the swimming capacity to successfully surpass these obstacles and the selective pressure that barriers in rivers and streams could exert on fish. Northern straight-mouth nase, an endemic potamodromous cyprinid fish species from the Northwest of the Iberian Peninsula, was selected to carry out volitionally swimming performance experiments in an open channel against three different flow velocities, using telemetry and video cameras. The use of thin-plate spline, on 10 landmarks, evidenced unknown patterns linked to velocity barriers. At lower flow velocity, size is the main factor explaining the swimming performance; thus, large individuals swim up more efficiently. In contrast, at high flow velocities, shape becomes the essential explanatory variable; thereby, streamlined body shapes with a higher relative position of the tail and a narrower caudal peduncle are more efficient. The obtained results show the existence of a relationship between fish morphology and swimming performance, with potential consequences due to selection pressures associated with velocity barriers and their implications on behavioural and dispersal processes. To sum up, velocity barriers could exert a selection pressure on nase populations, so the fishway design and removal should be (re)considered.

A new species of nine-spined stickleback, Pungitius modestus (Gasterosteiformes, Gasterosteidae), from northern Honshu, Japan

A new species of nine-spined stickleback, Pungitius modestus, is described based on the holotype and 17 paratypes (38.7–51.7 mm standard length) collected from the inland area of Yamagata Prefecture, northern Honshu, Japan. The new species is distinguished from the other species of Pungitius by the following combination of characters: 30–32 small unconnected lateral plates; dorsal-fin rays VIII–X (usually IX)+9–11; anal-fin rays 7–10 (usually 8); pectoral-fin rays 10; a short spiny dorsal fin base (26.5%–29.8% SL); the first spiny dorsal fin spine behind the pectoral-fin base; a long pre-anal fin (59.9%–67.4% SL); the anal-fin spine below the 1st–3rd dorsal-fin rays; a short pelvic-fin spine (6.3%–9.1% SL); a short anal-fin spine (4.1%–6.0% SL); a long caudal peduncle (14.3%–19.7% SL); no body markings; membranes of the dorsal-fin spines dark brown with black pigments; the entire male body, and soft dorsal and anal fins, becoming black in the breeding season; the anteroventral process of the ectocoracoid present; and the dorsal extension of the ascending process of the pelvis level with the dorsal-most actinost.

Stolephorus grandis, a new anchovy (Teleostei: Clupeiformes: Engraulidae) from New Guinea and Australia

The new anchovy Stolephorus grandis n. sp., described on the basis of 10 specimens collected from Papua, Indonesia, and Australia, closely resembles Stolephorus mercurius Hata, Lavoué & Motomura, 2021, Stolephorus multibranchus Wongratana, 1987, and Stolephorus rex Jordan & Seale, 1926, all having double pigmented lines on the dorsum from the occiput to the dorsal-fin origin, a long maxilla (posterior tip just reaching or slightly beyond the posterior margin of preopercle), and lacking a predorsal scute. However, the new species clearly differs from the others in having fewer gill rakers (35–39 total gill rakers on the first gill arch in S. grandis vs. > 38 in the other species), a greater number of vertebrae (total vertebrae 42–43 vs. fewer than 41), longer caudal peduncle (21.9–23.7% SL vs. < 20.8%), and the depressed pelvic fin not reaching posteriorly to vertical through the dorsal fin-origin (vs. reaching beyond level of dorsal-fin origin).

Pseudobagarius eustictus, a new species of catfish from northern Laos (Siluriformes: Akysidae)

Pseudobagarius eustictus, new species, is described from the Nam Heung drainage (a tributary of the Mekong River) in northern Laos. It is distinguished from congeners in having a unique combination of the following characters: a weakly-produced snout in which the upper jaw extends only slightly beyond the margin of the lower jaw when viewed ventrally, 3 tubercles on the posterior margin of the pectoral spine, eye diameter 8% HL, head width 24.1% SL, dark yellow dorsal and lateral surfaces of the head, pectoral spine lacking elongate extensions, pectoral fin reaching the pelvic-fin base when adpressed against the body, dorsolateral surfaces of body without longitudinal series of prominent tubercles, body depth at anus 13.7% SL, length of adipose-fin base 17.7% SL, caudal-peduncle depth 7.0% SL, and 33 vertebrae.

New record of the Red Shoulder Wrasse, Stethojulis bandanensis (Bleeker, 1851) (Perciformes, Labridae), from Korea

A single female juvenile specimen of Stethojulis bandanensis (Bleeker, 1851) was collected from Korea. The specimen is characterized by the 14 pectoral fin rays, the orange-red spot on upper pectoral fin base, and two small light-blue-edged black dots on the caudal peduncle. This species is the third species of the genus Stethojulis G&uuml;nther, 1861 in Korea, and the newly proposed Korean name for the species is &ldquo;Ju-hwang-jeom-mu-ji-gae-nol-lae-gi&rdquo;.

Oxynoemacheilus isauricus, a new nemacheilid loach from Central Anatolia (Teleostei: Nemacheilidae)

Oxynoemacheilus isauricus, new species, from the Lakes Beyşehir and Suğla basins in Central Anatolia is distinguished from all other species of the O. angorae group by having a very slender caudal peduncle (its depth 2.2–2.6 times in its length). The new species is further distinguished by having a short head (head length 21–24% SL), and a midlateral series of irregularly shaped blotches on the flank. Oxynoemacheilus isauricus is also distinguished by a minimum K2P sequence divergence of 7.5% and 8.0% in the mtDNA-COI barcode region from O. eregliensis and O. atili, its closest relatives.

Sardinella ventura n. sp. (Actinopterygii: Clupeiformes: Clupeidae), a new sardine from Mauritius

The new sardine Sardinella ventura n. sp. (Teleostei: Clupeiformes: Clupeidae) is described on the basis of 10 specimens collected from Mauritius. The new species is most similar to Sardinella dayi Regan 1917 in having non-deciduous scales with pores and discontinuous striae, a dark spot on the dorsal-fin origin, the pelvic fin with 8 rays, and similar number of gill rakers, in addition to very similar numbers of keeled scutes. However, the new species is distinguished from S. dayi by having a shorter caudal peduncle [6.2–7.6% SL (mean 7.0%) vs. 8.2–12.0% (9.2%) in S. dayi], larger eye [8.4–9.9% (9.0%) vs. 6.8–8.0% (7.4%)] and orbit [9.6–12.3% (10.7%) vs. 8.5–10.2% (9.3%)], longer pectoral [21.0–22.7% (21.5%) vs. 17.0–21.0% (19.8%)] and pelvic fins [12.5–13.5% (12.8%) vs. 10.4–12.2% (11.2%)], and a greater numbers of pseudobranchial filaments [17–19 (modally 17) vs. 18–22 (19)], lateral scale rows in longitudinal series [41–43 (41) vs. 38–42 (40)] and transverse scales [11 or 12 (12) vs. 11]. There were significant differences in seven meristic and 14 morphometric characters between the two species.

Genetic Differentiation of Clariid Populations using Microsatellite Markers in Kano State Rivers

This study aimed to investigate the genetic characterization of strains of Clariid fish species in some river bodies in Kano State using microsatellite markers.One hundred and seventy seven Clariid fish samples (Clariasgariepinus and Heterobranchuslongifilis) were collected from six rivers (Thomas, Ghari, Tiga dam, Duddurun Gaya, Karaye and Bagwai) in Kano state. Blood sample was taken from each fish sample by severing the caudal peduncle and drained into FTA cards for DNA extraction, Polymerase Chain Reaction and electrophoresis to determine genetic variation between the Clariid fish populations.Genealex 6.4 software package was used to analyse the resolve bands from DNA extraction to determine their base pair and genetic variation. Results showed that the Fst values ranged from 0.00 to 0.66, Fit ranged from -0.04 to 0.12, Fis ranged from -0.35 to -0.26. It indicated a large number of gene flow (exchange) among the populations with a range of 0.46 to 0.87. There was an established magnitude of genetic divergence (91.86%) among the populations as shown by the result of the percentage polymorphism which depends on the number of alleles detected per locus and their frequencies. It can be concluded that since there was no inbreeding as shown in the study, none of the population exhibited genetic uniqueness. The populations had a high genetic differentiation between populations but moderate differentiation within populations. The populations were outbred populations; an indication that relatives avoided mating in the population.