Descriptions of two new shell-dwelling species of Metriaclima (Cichlidae) from Lake Malaŵi, Africa

Metriaclima is the most speciose genus of rock-dwelling fishes (mbuna) found in Lake Malaŵi with 32 described species and with about 40 recognized forms that still await formal description. The genus is comprised of many geographically narrow populations restricted to specific habitat landmarks, such as reefs or islands. A few species have taken to the open sandy habitat where empty gastropod shells provide shelter. Two species of such shell-dwellers are here described as new. A combination of a black submarginal band in the dorsal and anal fins and five or fewer bars on the flank distinguishes Metriaclima ngarae sp. n. and M. gallireyae sp. n. from all other species of Metriaclima. Metriaclima ngarae sp. n. differs from M. gallireyae by a greater interorbital width and by a greater ratio of the snout length in the distance between snout tip and pelvic fin origin. Adult males of M. gallireyae have a blue-brown overall coloration obscuring the bar pattern on the flank while males of M. ngarae and those of the closely related M. lanisticola retain the bar pattern and have a coloration very similar to that of females.

Endothelin B Receptor Mutant Exhibits Craniofacial Dysmorphology Resembling Domestication Syndrome

Background: ETB-/- mutation is a major cause of HSCR, a neurocristopathy known for its enteric nervous system failure. Other than regulating ENCC migration, ETB mediates ET-1 clearance. Consequently, ETB may indirectly affect ET-1/ETA signaling, which controls CNCC migration and craniofacial development. Interestingly, it was hypothesized that “domestication syndrome” arise from changes in neural crest determining genes, including ETA and ETB. While ETA-/- animals are known to suffer severe dysmorphology resembling CATCH22 syndrome, we hypothesize that sl/sl rat, an ETB-/- HSCR model animal, may exhibit subtle craniofacial changes through indirect control. These features may share resemblance to those of domestication syndrome. Methods: Ten rat pups with an average age of 88 hours were anaesthetized with 5% isoflurane and culled via exsanguination. Tail tips were removed for genotyping. Head tissue were stained in 1.5% iodine for two weeks prior to micro-CT scanning. In vivo micro-CT scanning of cranial specimen was performed followed by ex vivo micro-CT scanning of 2 samples for image quality control. 3D visualization and analyses were performed using open-source program, Drishti. Cephalometric measurements were made based on selected craniofacial landmarks. Comparisons were made between sl/sl rats and the control group, which consisted of wild-type and heterozygotes. Results: Subtle reductions in facial measurements were seen in sl/sl rats when compared with the control group, ranging from 1.4% to 15%. These changes were observed in cranial, maxillary and mandibular parameters: total skull length, nasal length, nasal width, nasal cavity width, interorbital width, interlens distance, inner and outer canthal distance, maximal skull height, cranial length, intracranial length and width, interorbital width, and interzygomatic width. Consistently, craniofacial ratio indices showed sl/sl rat has a flatter cranium (skull height/skull length: 0.393 vs 0.413) and a shorter but broader nose (nasal-width/nasal-length: 0.794 vs 0.874). Additionally, subtle dystopia canthorum may be presented in sl/sl rat based on increased W index. While there was no discrepancy in dental number and morphology between the control and sl/sl groups, dimensional difference was detected. Conclusions: This study demonstrated subtle craniofacial changes are presented in ETB-/- HSCR model, supporting the idea that ETB regulates CNCC migration. The findings also implicate HSCR patient may have predisposing risks for conditions such as obstructive sleep apnea, cleft palate, or dental malocclusion. Lastly, these changes share resemblance with described domestication syndrome, supporting NCC-determining gene, ETB, may play a role in the formation of domestication.

Nothobranchius elucens, a new species of seasonal killifish from the upper Nile drainage in Uganda (Cyprinodontiformes: Nothobranchiidae)

Nothobranchius elucens, new species, from a seasonal habitat in the Aringa system of the Achwa River in the upper Nile drainage in northern Uganda, is described. It belongs to the N. rubroreticulatus species group, whose members are characterised by male coloration of anal and caudal fins with slender light blue subdistal band and slender dark distal band. Nothobranchius elucens is distinguished from all other members of the genus by the following characters in males: body colouration golden-grey with brown scale margins creating irregular vertical stripes on trunk; anal fin yellow with brown spots proximally, with slender brown median band, followed by a slender light blue subdistal band and a slender black distal band; caudal fin brown proximally and medially, followed by a slender light blue subdistal band and a slender black distal band; dorsal fin golden with irregular brown stripes and narrow light blue subdistal band and with narrow black distal band. Furthermore, it differs from the closest known relative, N. taiti, also by the morphometric characters of having a smaller head length of 29.5–33.1 % SL; smaller prepectoral length of 31.2–33.9 % SL; greater head depth of 81–87 % HL; greater interorbital width of 43–49 % HL; and greater caudal peduncle length of 145–152 in % of its depth.

Four new species of Serranochromis (Teleostei: Cichlidae) from the Cuanza and Okavango river systems in Angola, including a preliminary key for the genus

The present study describes Serranochromis alvum n. sp., Serranochromis swartzi n. sp., Serranochromis cuanza n. sp., and Serranochromis cacuchi n. sp. from Angolan tributaries of the Cuanza and Okavango systems in Angola. The presence of four or five scale rows between the posterior margin of the orbit and the ascending arm of the preoperculum, the presence of widely set unicuspid teeth on the jaws, widely separated gill rakers, and anal fins with egg ocelli place these four species in Serranochromis. The Serranochromis described herein are distinguishable based on a combination of morphological and meristic characters, as well as pigmentation patterns. The interorbital width (14.3–15.9 % HL) of S. alvum is narrower than that of S. swartzi (17.6–19.8), S. cuanza (16.3–18.0), and S. cacuchi (20.0–21.7). Moreover, the interorbital width of S. cacuchi is greater than the other three described species. Serranochromis swartzi has a smaller preorbital depth (16.2–18.9 % HL) and snout length (29.6–31.9 % HL) than Serranochromis cuanza (PD 19.1–22.2, SNL 35.2–39.6 % HL). Serranochromis alvum is known only from the type locality at Cuito-Cuanavale at the junction of the Cuito and Cuanavale rivers, tributary to the Okavango River in Angola. Serranochromis swartzi is known only from the type locality in the Cuanza River, Angola. Serranochromis cuanza is restricted to the Cuanza River, below Capanda Dam, Angola, while S. cacuchi is known only from the Cacuchi River, a tributary of the Cuchi-Cubango River in Angola. The limited distribution of all four species and the absence of many congeners suggest, that in addition to previous studies that invoked a lacustrine speciation model, vicariance through drainage isolation seems to have played an important role in driving speciation in this group. The minimum polygon clusters that are formed when the first principal components of the meristic data are plotted against the second sheared principal components of the morphometric data show separation of the four new species.

Systematic revision of the flatfish genus Peltorhamphus Günther, 1862 (Teleostei: Pleuronectiformes: Rhombosoleidae), including description of a new species from Southeastern New Zealand, with biological and ecological summaries for the species

The flatfish genus Peltorhamphus Günther, 1862 (Pleuronectiformes: Rhombosoleidae) and its constituent species are redescribed based on examination of 1885 specimens. Four species are considered valid: three previously described (P. novaezeelandiae Günther, 1862, P. latus James, 1972, and P. tenuis James, 1972) and P. kryptostomus n. sp., described herein. Peltorhamphus novaezeelandiae, P. latus, and P. tenuis have widespread distributions on soft sediments in shallow coastal and inner continental shelf waters off both islands of New Zealand. Peltorhamphus novaezeelandiae has also been reported at the Chatham Islands. Previous reports of P. novaezeelandiae from Norfolk Island are erroneous. Peltorhamphus kryptostomus n. sp. has the most restricted geographic distribution in shallow coastal waters of the Otago-Southland region along the southeastern coast of South Island. The four species of Peltorhamphus are morphologically similar and overlap in many traditional meristic and morphometric features rendering identifications difficult, especially of juveniles and earlier life-history stages. Furthermore, throughout New Zealand waters, as many as three of the species possibly occur sympatrically, while in inshore areas of southeastern South Island, all four species may occur in sympatry. Novel morphological characters discovered in this study, combined with traditional diagnostic characters were used to identify and diagnose the species. Peltorhamphus tenuis is the most distinctive of the four, differing from congeners in the following combination of characters: greater length of second ocular-side pectoral-fin ray; its higher numbers of dorsal- and anal-fin rays and total vertebrae; having a series of small scales (best developed in specimens >70 mm SL) on blind sides of dorsal- and anal-fin rays (scales absent in congeners); its elongate body; and ocular-side pigmentation. The other three species are more similar morphologically and have frequently been misidentified both in fish collections and in some previous literature on these fishes. Of these three, P. novaezeelandiae, the largest in the genus, is distinguished from congeners by the combination of: its large size (reaching 510 mm SL vs. ≤ 200 mm SL); rounded head shape; blind-side squamation; the second ocular-side pectoral-fin ray shorter than body depth; ontogenetic variation in interorbital width; greater distance (4–8 scales wide) between ventral margin of lower eye and dorsal (upper) margin of rostral hood above the mouth; and 2–6 fleshy, finger-like filaments on the inner anteroventral margin of the fleshy skinfold on the ocular-side lower jaw. Peltorhamphus latus differs from congeners by the combination of: its short (maximum 150 mm SL), relatively deep body and bluntly pointed snout; blind-side squamation; relatively long, robust gillrakers on first gill arch, with upper limb gillrakers long, but not usually overlapping tips of dorsalmost gillrakers on the lower limb; black pigment on entire roof of mouth; relatively large eyes and narrow interorbital width (without significant ontogenetic variation); short diagonal distance (usually 2–3 scales wide) between ventral margin of lower eye and dorsal (upper) margin of rostral hood above the mouth; and absence of finger-like filaments on the inner anteroventral margin of the fleshy skinfold on the ocular-side lower jaw. Peltorhamphus kryptostomus n. sp. is distinguished from congeners by the combination of: its deep body and smoothly rounded snout; blind-side squamation; long, robust gillrakers on the first gill arch, with some posterior gillrakers on the upper limb overlapping tips of the first and second dorsalmost gillrakers on the lower limb; black pigment on the entire roof of the mouth; relatively large eyes and relatively narrow interorbital width; wide distance between ventral margin of lower eye and upper margin of rostral hood (3–6, usually 4–5, scales wide); and 1–4 finger-like filaments on the inner anteroventral margin of the fleshy skinfold on the ocular-side lower jaw. Ecological and life-history information are summarized for each species, and a key to juveniles > 40 mm SL and adults is also provided. Re-assessment of the number of valid species of Peltorhamphus provides better understanding of species diversity within this genus and within the Rhombosoleidae, as well as that for the flatfish assemblage residing in New Zealand waters.

Revalidation of the Spanish stone loach Barbatula hispanica (Lelek, 1987) (Teleostei, Nemacheilidae) according to morphological and mitochondrial data

This study revalidates Barbatula hispanica, previously considered a junior synonym of B. quignardi. This species is found in the Ebro drainage and in Cantabria (Spain) as well as in the Adour drainage (Southwestern France). It is characterized by an upper lip with a well-marked medial incision and an interorbital width 18.5–33.7% of the HL. The species delineation is corroborated by the cytochrome oxidase subunit 1 molecular marker. We provide the sequence of 12S rDNA (950 bp) as reference for environmental DNA studies, and discuss also the taxonomy of B. quignardi which would be restricted to the Lez River.

A new species of Egglestonichthys (Teleostei, Gobiiformes, Gobiidae) from Okinawa Island, Japan

Egglestonichthys fulmensp. nov. (Teleostei: Gobiidae) is described on the basis of a single specimen (21.7 mm in standard length) collected from 250 m depth off Okinawa Island, Ryukyu Islands, Japan. The new species is characterized by the following combination of characters: anal-fin rays I, 9; pectoral-fin rays 17, lower rays not free from membrane; longitudinal scale series 25; transverse scales 8; pre-dorsal-fin scale rows 8; cheek and opercle naked; pelvic frenum absent; caudal fin lanceolate, its length 32.2% of SL; interorbital width very narrow, 1.2% of HL (much narrower than pupil diameter); no spicules or odontoid processes on outer surface of gill arches; and body whitish, upper half with broken zigzag pattern of bright yellow patches and associated scattered black melanophores in fresh specimens (melanophores retained in preserved specimens). Several characters, including pectoral-fin ray count, interorbital width, and coloration uniquely distinguish the new species from congeners.

Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph

The taxonomy of the gadiform fish family Macrouridae (sensu stricto) in the northwestern Pacific off Japan and adjacent waters is critically reviewed on the basis of 7846 specimens. A total of 76 species belonging to 18 genera is recognized, including four new species of the genera Coelorinchus (2 species), Kuronezumia (1), and Nezumia (1). Coelorinchus lanceolatus sp. nov. superficially resembles Coe. anatirostris Jordan & Gilbert in Jordan & Starks, 1904, but differs most notably from that species in having a distinctly longer snout (107% of the postrostral length vs. 60–88%). Coelorinchus nox sp. nov. is closely similar to Coe. smithi Gilbert & Hubbs, 1920, but readily differs from the latter in that the occipital scales are covered with short, erect, needle-like spinules in widely divergent, comb-like rows (vs. moderately reclined, keel-like to knife-like spinules in saw-toothed rows). Kuronezumia endoi sp. nov. is a distinctive species among the genus, and is clearly diagnosed from other congeners in having the highest number of pelvic-fin rays (15 vs. ≤14). Nezumia rara sp. nov. closely resembles N. tomiyamai (Okamura, 1963), but they can be distinguished from each other by the combination of a number of morphometric characters, including the orbit-preopercle distance, interorbital width, pelvic-fin length, and length of gill slit. New and reconfirmed synonymies include: Coe. abbreviatus Chu & Lo in Chu, Chan & Chen, 1963 and Coe. intermedius Chu & Lo in Chu, Chan & Chen, 1963 with Coe. multispinulosus Katayama, 1942; Coe. productus Gilbert & Hubbs, 1916 with Coe. anatirostris; Coe. asteroides Okamura, 1963 with Coe. hige Matsubara, 1943; Coe. sparsilepis Okamura & Yatou, 1984 with Coe. parallelus (Günther, 1877); Coryphaenoides filamentosus Okamura, 1970 with Cor. cinereus (Gilbert, 1896); Cor. liocephalus (Günther, 1887) with Cor. leptolepis Günther, 1877; Cor. spinulosus (Gilbert & Burke, 1912) with Cor. acrolepis (Bean, 1884); and Ventrifossa fusca Okamura, 1982 with V. misakia (Jordan & Gilbert in Jordan & Starks, 1904). Lectotypes are designated for Coe. parallelus, Cor. asper Günther, 1877, Cor. liocephalus, and Cor. nasutus Günther, 1877. Previous records of N. burragei (Gilbert, 1905) and N. propinqua (Gilbert & Cramer, 1897) from Japan represent misidentifications, and these species are eliminated from the list of Japanese grenadiers. Coryphaenoides armatus (Hector, 1875) and Cor. leptolepis are recorded for the first time from the hadal zone. All species are illustrated, with full descriptions for 14 species. Dichotomous keys to genera and species are also provided. The distribution of each species in the study area is revised based on the specimens examined here, with re-identification of voucher specimens of most previous geographical records.

Revalidation of Enteromius alberti and presence of Enteromius cf. mimus (Cypriniformes: Cyprinidae) in the Lake Edward system, East Africa

A revision was done on the species of Enteromius Cope, 1867 (Cypriniformes: Cyprinidae) from the Lake Edward system with a smooth, flexible third unbranched dorsal fin ray without serrations. Specimens with these characteristics had previously been attributed to E. perince and E. stigmatopygus. A combination of a genetic (COI, mtDNA) and a morphometric approach was used. Based on the COI gene, we found two groups with a distance of 8.5%, though neither of the two corresponded to E. perince or E. stigmatopygus. One group revealed to be conspecific with E. alberti, previously a synonym of E. stigmatopygus, described from the Rutshuru River, May-Ya-Moto (DRC, Lake Edward system), and revalidated here. In addition, E. cercops, described from the Nzoia River (Kenya, Lake Victoria basin), is put in synonymy with E. alberti. The second group was most similar to E. mimus, but differed morphologically somewhat from the types of E. mimus. Therefore, specimens of this group were identified as E. cf. mimus. Morphologically, E. alberti can be separated from E. cf. mimus based on a higher number of lateral line scales and smaller values for interorbital width, pre-pelvic distance, body depth, maximum and minimum caudal peduncle depth, head width and head depth.

Phenotypic diversity in an endangered freshwater fish Squalius microlepis (Actinopterygii, Leuciscidae)

Squalius microlepis was examined from recent and historical collections within the known range of the species with special emphasis on intraspecific variability and variations, and compared to its closest relative species S. tenellus (in total, 193 specimens; 33 absolute and 52 proportional measurements and ratios, and 12 counts including vertebrae). Squalius tenellus was perfectly differentiated in all statistical analyses and can be diagnosed by 76–95 (vs. 64–80) scales in lateral series, 68–83 (vs. 58–77) lateral-line scales, (17)18–20 (vs. 13–16(17)) scales above lateral line, and (7)8–10 (vs. 4–7) scales below lateral line. Squalius microlepis was morphologically heterogeneous, with two phenotypes readily distinguishable (phenotype 1 corresponding to S. microlepis s. str. as defined by its lectotype) by a combination of many characters; those contributing most to the discrimination were number of gill rakers, length of lower jaw (% interorbital width), and head length (% SL). Only phenotype 1 was found in the Ričina-Prološko Blato-Vrljika karst system; most of the specimens from the lower Matica and the Tihaljina-Trebižat karst system were identified as phenotype 2; the sample from karstic poljes near Vrgorac contained both phenotype 1 and 2, and individuals of intermediate morphology. As very limited molecular data exist on the two phenotypes of S. microlepis, we refrain from any taxonomic conclusions until new molecular approaches (and new markers) are used. We also report on a dramatic reduction of the area of distribution and abundance of S. microlepis in recent years.