Predorsal Scales Research Articles

A new species of Hoplostethus from Sumatra, eastern Indian Ocean, with comments on its most similar congeners (Trachichthyiformes: Trachichthyidae).

A new species of the roughy fish genus Hoplostethus, subgenus Leiogaster, is described based on three specimens collected from Sumatra, Indonesia. This species can be distinguished from its congeners by the following characteristics: gular region covered with ctenoid scales; pelvic-fin spine smooth on its anterior edge; head depth subequal or smaller than its length (37.2%-38.6% standard length [SL], or 94.7%-99.2% head length [HL]); pectoral-fin length 35.6%-37.8% SL, reaching beyond a vertical through anal-fin origin; abdominal scutes well developed, 12-16; pectoral-fin rays uniformly black, 17-19; gill rakers on the first arch 6-7 + 1 + 13-14 = 21; pre-dorsal scales 24-27; and pyloric caeca 32. A detailed description is provided along with comparisons with its congeners. Additionally, diagnostic characters of the congeners and literature records of Hoplostethus rubellopterus and Hoplostethus melanopus are discussed.

A new species of Opsariichthys (Teleostei, Cypriniformes, Xenocyprididae) from Southeast China.

Opsariichthysiridescens sp. nov. is described from the Qiantang and Oujiang rivers in Zhejiang Province and a tributary of the Yangtze River adjacent to the Qiantang River. It is distinguished from congeners by the following combination of morphological features: no obvious anterior notch on the tip of the upper lip; 45-52 lateral-line scales; 18-21 pre-dorsal scales; two rows of pharyngeal teeth; a maxillary extending to or slightly beyond the vertical anterior margin of the orbit in adult males; a pectoral fin extending to the pelvic fin in adult males; nuptial tubercles on the cheeks and lower jaw of males, which are usually united basally to form a plate; uniform narrow pale pink cross-bars on trunk and two widening significantly on caudal peduncle. Its validity was also supported by its distinct Cyt b gene sequence divergence from all congeners and its monophyly recovered in a Cyt b gene-based phylogenetic analysis.

Opsarius siangi, a new Chedrinae fish species from the Brahmaputra drainage, India

Opsarius siangi sp. nov., a previously undocumented species, has been identified from Siang River, Pasighat, Arunachal Pradesh, India. This newly described species is distinguished by a suite of unique morphological characteristics, notably including a complete lateral line, consisting of 65–77 scales, 32–39 pre-dorsal scales, 12–15 scales positioned between dorsal fin origin and lateral line, presence of two pairs of barbels, body depth ranging from 18.80% to 27.42% of standard length and a distinct pattern of 8–15 vertical bars adorning the body. A comprehensive genetic analysis was conducted by scrutinizing 78 Cytochrome oxidase I (COI) sequences extracted from Chedrinae fishes, with particular focus on Opsarius and Barilius genera. Phylogenetic analysis revealed that O. siangi sp. nov. occupies a distinctive clade, displaying close affinity with O. shacra. Intraspecific K2P genetic divergence, assessed at 0.02, falls well within established species delineation thresholds, while interspecific divergence in comparison to O. shacra was recorded at 0.112. Complementary species delimitation methodologies, including BIN and bPTP, further underscore taxonomic uniqueness of O. siangi sp. nov., within Chedrinae family. This description enriches our understanding of biodiversity within Siang River ecosystem and underscores the merit of employing multi-pronged approaches in taxonomic investigations.

Population variation of Diapoma pampeana (Characiformes, Characidae, Stevardiinae) from an isolated coastal drainage in Uruguay, with new records: comparing morphological and molecular data

Diapoma pampeana was recently described to occur in the upper Negro basin in Uruguay and Brazil. An isolated population tentatively identified as D. pampeana from the Pando stream, a perturbed coastal drainage in Uruguay, is studied and compared under the light of morphological and molecular data to test if there is evidence to consider it as a separate species. New geographical records for the species are presented and included in the comparisons. The specimens analyzed were pooled into four groups: Pando, Santa Lucía, Middle Negro and Upper Negro. We analyzed 32 morphological characters using statistical procedures and recovered a COI-based phylogeny of different populations of D. pampeana to test if they may represent different species. Size-corrected PCA revealed that the Pando and Upper Negro groups are greatly diverging in both morphometric and meristic data along PC1 (mainly by the snout to dorsal-fin origin, dorsal to adipose-fin origins, number of longitudinal scales and predorsal scales). This deviating pattern was also obtained in a cluster analysis. The Santa Lucía and Middle Negro groups were found to be intermediate morphotypes. In contrast, molecular analyses revealed that the Pando and Upper Negro specimens resemble genetically and, thus, are placed together in the Neighbor-joining and Bayesian topologies, as part of a monophyletic Diapoma. We proposed that the Pando population, despite its deviating morphology observed, can be classified as D. pampeana. Therefore, this population constitutes a remarkable example of an isolated population that is morphologically divergent but genetically similar to the geographically most distant conspecific population.

Two new species of freshwater goby (Teleostei, Gobiidae) from the Upper Youshui River, Chongqing, China.

Two previously unknown species of Rhinogobius have been discovered in the streams of the Upper Youshui River, within the Yuan River Basin, Xiushan County, Chongqing, China. These new species are named as Rhinogobiussudoccidentalis and Rhinogobiuslithopolychroma. Phylogenetic analysis based on mitochondrial genomes revealed that R.sudoccidentalis is genetically closest to R.reticulatus, while R.lithopolychroma shares the greatest genetic similarity with R.leavelli. Morphological distinctions allow for the clear differentiation of these species. Rhinogobiussudoccidentalis sp. nov. is characterized by having VI-VII rays in the first dorsal fin and I, 8-9 rays in the second dorsal fin. The longitudinal scale series typically consists of 22-24 scales, while the transverse scale series comprises 7-8 scales. Notably, the predorsal scale series is absent and the total vertebrae count is 12+17=29. Rhinogobiuslithopolychroma sp. nov. can be distinguished from other species by the presence of 13-15 rays on the pectoral fin. Its longitudinal scale series ranges from 30 to 33 scales, with no scales in the predorsal area. The total vertebral count is 30, with 12 precaudal and 18 caudal vertebrae. The head and body of this species are light gray with irregular orange markings on the cheeks and opercle. Through morphological and molecular analyses, it has been confirmed that R.lithopolychroma and R.sudoccidentalis represent novel species within the Rhinogobius genus.

Description of a New Species Named Cabillus wui of Genus Cabillus (Teleostei: Gobiiformes: Gobiidae) from Southeastern China Sea

A tiny goby collected from Taiwan Strait which has been identified as a member of genus Cabillus seems individual, named Cabillus wui sp. nov.. Many pieces of evidence point to it as a new species. This species could be distinguished as follows. There is a dark blotch on the first-dorsal-fin membrane; predorsal scales 6; the first dorsal spine very depressed, is the longest, and is very close to the second dorsal spine; pelvic sucker is emarginated; median predorsal scales is present; all pectoral-fin elements are 20 branched soft rays; every fin nearly completely patternless and transparent except slightly patterned first dorsal fin; dorsal fin possesses 10 soft rays. This species is described in this article with the comparison of the other species in the genus Cabillus. An overview of this genus is also given. Besides, a key for distinguishing the species in this genus is also provided.

Description of a new species of the genus Awaous Valenciennes, 1837 (Gobiiformes: Oxudercidae) from the middle stretch of the Mahanadi River, Odisha, India, with comments on the Awaous species from India.

A new species of the genus Awaous (Oxudercidae), Awaous motla sp. nov., is described based on 18 specimens collected from the Mahanadi River near Sonepur, Subarnapur District, and 3 specimens from the same river near Boudh bridge, Boudh District of Odisha, India. This species is distinct from its congeners by having a combination of characteristics: relatively small eyes, diameter of 6.6-8.4 in head length (LH); robust and long snout, 2.0-2.6 in LH; eye diameter 2.7-4.1 in snout length; cephalic sensory pore system interrupted with eight pores; predorsal scales 13-15; longitudinal scale series 55-58; gill rakers 2 + 1 + (6-7) on the first gill arch; teeth small, conical, and in a single row on the upper jaw and multiserial (2-3) on the lower jaw. This species is also differentiated from some of its congeners in the nucleotide composition of the cytochrome c oxidase I gene by 8.3%-13.8% Kimura two-parameter (K2P) distance and belongs to a separate cluster in the maximum likelihood tree analysis. This finding is also supported by the species delimitation analysis based on Assemble Species by Automatic Partitioning. The new species holds high commercial value in its locality and needs special conservation attention for sustainable utilization.

Cabdio occidentalis, a new species from Lake Mashkid basin and the Makran region (Teleostei: Danionidae).

Cabdio occidentalis, new species, is described from the Lake Mashkid basin and the Makran region of Iran. It is distinguished from other species of the genus by a combination of characters: 3842+12 total lateral-line scales, 1923 predorsal scales, 911 pectoral-fin rays, and the absence of a keel between the pelvic-fin base and the genital papilla. The cytochrome c oxidase subunit I (COI) sequence separates C. occidentalis from C. morar, its closest congener, by a p-distance of 5.5%.

Molecular identification and morphological description of an unrecorded goby Bathygobius coalitus (Perciformes: Gobiidae), from Jeju-do, Korea

A single specimen of the whitespotted frillgoby, Bathygobius coalitus (Bennett, 1832), was collected from Jeju-do, Korea, in October 2020. The species is characterized by the absence of a flap on the nostril, the extension of the anterior tip of the predorsal scale beyond the posterior margin of the preopercle, and a pectoral fin with four upper rays free from membrane, each divided into two branches. Mitochondrial DNA cytochrome oxidase subunit I analysis revealed that the specimen corresponds to B. coalitus (99.8% similarity) rather than any of the three previously known congeneric Korean species. The species is newly recorded in the Korean fish fauna, and the proposed Korean name for the species is “Heuin-jeom-mu-nui-mang-dug”.

Hoplostethus roseus, a new roughy fish from the western Pacific based on morphology and DNA barcoding (family Trachichthyidae).

A new species of the roughy fish genus Hoplostethus is described from 11 types and a non-type specimen collected from Taiwanese waters. It can be distinguished from its congeners by a combination of characters: pectoral-fin rays 14-17 (modally 15-16); pyloric caeca 65-84; total gill rakers 19-20; predorsal scales 18-22; oral cavity, branchial chamber, top and underside of tongue, and peritoneum uniformly black; distal margin of membrane between dorsal-fin spines black; caudal fin without a black margin; caudal-fin base brownish. Comparisons of the new species with similar species are provided. DNA barcoding supports the monophyly of the new species, which appears to be closely related to Hoplostethus japonicus [average cytochrome c oxidase subunit I Kimura-2-parameter (COI K2P) distance of 4.1%].

Redescription of the goby Glossogobius tenuiformis Fowler, 1934 (Teleostei: Gobiidae) and assignment of Oman Glossogobius populations: a morpho-molecular approach.

Glossogobius giuris was originally described as Gobius giuris from the Ganges River, India. However, based on the uncertainty of its type locality and its apparent widespread distribution, a comprehensive study is being carried out to define the correct taxonomic status of this taxon. The South African population of the Glossogobius from St. Lucia Lake, KwaZulu-Natal was described as Glossogobius tenuiformis by Fowler in 1934. It has usually been considered as Glossogobius giuris but Hoese and Hammer indicated that it was a distinct species (2021: 83). Here, based on morphological characters and a molecular data set, we redescribe Glossogobius tenuiformis and assign the Oman populations of Glossogobius to this species. Glossogobius tenuiformis is distinguished from G. giuris by the absence or very short (and often only a few papillae long) sensory papilla line 6; presence of single rows of the sensory papillae in each cheek line, 1216 pre-dorsal scale counts, and 1+1+911, usually 1+1+10, gill rakers on outer face of first arch. Glossogobius tenuiformis is also distinguished by molecular characters. Glossogobius tenuiformis shows 16% genetic distance with other members of this species complex, that includes G. laticeps from Vietnam, Bangladesh and China, G. giuris from South Africa and India and giuris C from India, Myanmar, Nepal, Bangladesh and Vietnam, and the highest genetic distance (24%) with G. circumspectus.

Stolephorus lotus, a New Anchovy (Teleostei: Clupeiformes: Engraulidae) from the Northern Territory, Australia.

A new anchovy Stolephorus lotus sp. nov., is described based on 30 specimens collected from Van Diemen Gulf, Northern Territory, Australia. The species closely resembles Stolephorus acinaces Hata, Lavoué and Motomura, 2020 and Stolephorus andhraensis Babu Rao, 1966, in having a long maxilla (posterior tip just reaching or extending slightly beyond the posterior margin of the opercle), indented posterior preopercular margin, anal fin with 16-18 branched fin rays, and 21-23 lower gill rakers, and lacking a predorsal scute and pelvic scute spine. However, the new species differs from the other two species in having higher counts of longitudinal series of scale rows and predorsal scales (37-39 and 20 or 21, respectively vs. 35-38 and 17-19 in the other two) and a more anteriorly located anal-fin origin (below bases of sixth to eighth dorsal-fin rays vs. eighth to tenth dorsal-fin rays).

A new species of Hoplias malabaricus species complex (Characiformes: Erythrinidae) from the Crepori River, Amazon basin, Brazil.

A new species belonging to the Hoplias malabaricus complex from the Amazon basin, Brazil, is described. The new species is characterized by 15-16 predorsal scales, 37-39 lateral-line scales, 5 scales from dorsal fin to lateral line, 38-39 vertebrae, iii-iv, 7-8 anal-fin rays, ii-iv, 12-15 caudal-fin rays, last vertical series of scales on the base of caudal-fin rays forming a straight line, 6-7 dark bands in anal fin and no distinctive dark bands or blotches on flanks. The new species is also distinguished from other congeners of the H. malabaricus species-group by means of landmark-based morphometrics and DNA Barcoding (Cytochrome c Oxidase I gene). An identification key to species of the H. malabaricus species complex is provided.

Taxonomic revision and redescription of Microphysogobio hsinglungshanensis, the type species of Microphysogobio Mori, 1934 (Cypriniformes: Cyprinidae).

The genus Microphysogobio was established by Mori [Mori, T. (1934). The fresh water fishes of Jehol. In Report of the first scientific expedition to Manchoukuo. 1: pp. 1-61] based on a single specimen (Microphysogobio hsinglungshanensis) collected in the Luanhe River basin, Xinglong County, Hebei Province, China. Because the genus characteristics were derived from its type species, M. hsinglungshanensis, the detailed description is essential. In addition, to distinguish M. hsinglungshanensis and Microphysogobio chinssuensis, the description based on holotype and more specimens is needed. M. hsinglungshanensis can be distinguished from all other congeners by the following combination of characters: mouth shallow arc shaped and inferior; medial pad on lower lip inverted trapezoid and usually grooved; barbel short, 6.9%-14.3% in head length; lateral-line scales 38-39; ventral region between pectoral-fin origin and pelvic-fin origin scaleless; scales above lateral line 4-4.5; predorsal scales 10-11; vertebrae 4+ 32-34; caudal-fin membrane with two or three rows of irregular black spots. The characteristics of this genus were redefined based on M. hsinglungshanensis in this study.

Taxonomic revisions of Altigena laticeps and A. lippa (Cyprinidae: Labeoninae) from the Mekong River Basin.

Altigena laticeps, previously considered a junior synonym of A. lippa, is revalidated and re-described based on morphological examinations of type and non-type material. This species, found in the Upper Mekong River basin in China, can be distinguished from A. lippa based on higher numbers of lateral-line scales (40-42 vs. 34-39), predorsal scales (14-16 vs. 9-12), and circumpeduncular scales (20 vs. 16). Altigena lippa, from the Lower Mekong River basin in Lao PDR, Myanmar, Thailand, and Vietnam is also re-described. Four species of Altigena are herein recognized in the Mekong River basin: A. elegans, A. laticeps, A. lippa, and A. yunnanensis.

Assessment of morphological variations in wild populations of Nile tilapia from South West Nigeria

Abstract. The pattern of morphological variations among Oreochromis niloticus (Linnaeus, 1758) (Cichlidae; Teleostei) from three populations from South West Nigeria (Asejire reservoir, Ureje reservoir and Ogbese River were examined (n=10 speciments from each water body) with a view to investigate the genetic diversity using morphometrics and meristics indices. In general, 77.22% of the total variation in the sampled populations is from first principal component (PC1) and the characters that contributed to this variation are with pre-dorsal length, pre-pectoral length, pre-anal length, dorsal spine length and anal spine length. Canonical variate analysis (CVA) showed that O. niloticus populations from the three water bodies formed a separate cluster from each other and that there was an intersection between the Asejire and Ureje reservoirs samples and the Asejire reservoir with Ogbese River samples. However, the samples from Ureje reservoir and Ogbese River had no intersection. Cluster analysis revealed two major clusters with Ureje reservoir samples belong to one and Ogbese River and Asejire reservoir fall in the other cluster. Principal Components for meristic (PC1 and PC2) accounted for 46.49% and 24.17% revealed that transverse scales and scales surrounding the caudal peduncle, pre-dorsal scales accounted for the variation. The CVA revealed that of all the populations sampled, samples from Ureje reservoir are more diverse that the other two populations. The research disclosed that there is variation in O. niloticus populations from the three water bodies, which could be a result of genetic structure and environmental conditions, being major factors affecting morphological variability among different geographical populations. Further study on genetic differentiation of individuals from different species is necessary to confirm findings of the present study.

Two new species of the genus Chelidoperca (Perciformes: Serranidae) from the Andaman Sea, eastern Indian Ocean.

Two new species of the genus Chelidoperca are described from specimens collected in 2015 and 2018 from the Andaman Sea, off the coast of Myanmar during trawl bottom surveys conducted by the R/V Dr. Fridtjof Nansen. Chelidoperca myathantuni sp. nov. is described based on 15 specimens (74.3-129.5 mm SL) from 101-185 m depth, which can be distinguished from all congeners by the following combination of characters: 3 (2 full-sized plus 1 half-sized) scale rows between lateral line and middle of spinous dorsal-fin base; 42-44 (modally 44) pored lateral-line scales; 16 pectoral-fin rays; interorbital scales extending to mid-orbit level; scales on ventral surface of lower jaw restricted to the angular (not extending onto the dentary); enlarged caniniform teeth on the upper jaw; side of body with longitudinal dashed black stripe; dorsal fin pale yellow with reddish pigment mostly restricted at base of spines and rays. Chelidoperca flavimacula sp. nov. is described based on eight specimens (49.7-70.7 mm SL) from 84-131 m depth, which can be distinguished from all congeners by the following combination of characters: 3 (2 full-sized plus 1 half-sized) scale rows between lateral line and middle of spinous dorsal-fin base; 42-45 (modally 42) pored lateral-line scales; 9-10 (modally 10) scale rows below the lateral line; 6 predorsal scales; 16-17 (modally 16) circumpeduncular scales; 5 scales rows on cheek; interorbital scales extending to mid-orbit level; anal fin with yellowish distal margin and three or four rows of bright yellow spots over its proximal half.

Rediscovering species: redescription of Bryconops gracilis (Characiformes: Iguanodectidae), an often-misidentified species

ABSTRACT A redescription of Bryconops gracilis is provided, a species poorly known for more than a century. Bryconops gracilis differs from all congeners by having the following combination of features: eight branched pelvic-fin rays, 31-36 anal-fin rays, 15-17 predorsal scales arranged in a regular series, two rows of premaxillary teeth, and 53-60 lateral-line scales. The species was often misidentified as B. alburnoides by sharing an overall elongated body shape, caudal fin yellowish in life, and a high number of lateral-line scales. A diagnosis between B. alburnoides and B. gracilis is provided. The holotype of B. gracilis which for many years had whereabouts unknown, was recovered, examined and illustrated by CT-Scan. Additionally, more detailed information about the type locality, morphology, color pattern (including in living specimens), habitat and distribution pattern of species are provided.

A New Species of Snakehead (Teleostei: Channidae) from East Khasi Hills, Meghalaya, Northeastern India

A new species of colorful snakehead from Meghalaya, northeastern India is distinguished from all its congeners by possessing a uniform bright blue to bluish-green body, bright-blue dorsal, anal, and caudal fins, submarginally black with white distal margin, series of brown to maroon-red, rounded, oblong or clover-shaped blotches or spots on dorsolateral, postorbital, and ventrolateral region of head, continued on body forming oblique pattern or randomly distributed. The new species superficially resembles C. pardalis and C. bipuli in appearance, but it can be distinguished from both in having brown to maroon-red, rounded, oblong or clover-shaped blotches or spots on head and sides of the body (vs. possession of well-defined, black to brown, rounded to oblong spots), fewer pre-dorsal scales (7 vs. 8–9), more caudal-fin rays (15 vs. 13), and more vertebrae (49 vs. 45). The new species differs from both C. pardalis and C. bipuli by Kimura's two-parameter (K2P) distance of 4.2–4.8 and 4.9–6.0% in the coxI gene sequence. A key to the snakehead Gachua group of the Eastern Himalayan region is provided herein.

Short Communication: A new cyprinid fish Barilius cyanochlorus from Kerala, India

Abstract. Plamoottil M, Vineeth K. 2020. Short Communication: A new cyprinid fish Barilius cyanochlorus from Kerala, India. Biodiversitas 21: 5389-5393. A new Barilius species is described from a small freshwater stream at Kasargod district of Kerala, India. It can be distinguished from its congeners in having a body with blackish-brown dorsal and upper laterals, greenish-yellow middle part and silvery lower lateral part, 8 vertical bands on mid-lateral region, each of these bands with 2 segments-lower blue part and upper green part, a large round blotch on the caudal base with similar color pattern, dorsal fin with basal 2/3 portion brown and distal 1/3 part orange-red, anal fin orange-red, pectoral fin pale reddish, 14-16 pre-dorsal scales and 37-39 lateral line scales. The new species is taxonomically analyzed, compared with its congeners, scientifically named and described.
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