[Ichthyology • 2026] Crossorhombus pescadores • A New lefteye Flounder of the Genus Crossorhombus (Teleostei: Bothidae) from Penghu Islands, western Taiwan

Crossorhombus pescadores 

 Amaoka, Su & Ho, 2026

DOI: doi.org/10.3897/zookeys.1273.167628

Abstract

A new lefteye flounder, Crossorhombus pescadores sp. nov., is described based on five specimens collected from Penghu Islands. This new species differs from the other four congeners by having a pair of small black spots on the caudal fin, a horizontal triangular bluish-black marking on the blind side of body in male, the front wings of the marking reaching the base of dorsal and anal fins, and a combination of morphometric characters, including a larger head, deeper body, smaller eyes, fewer dorsal- and anal-fin rays and lateral-line scales, and other characters. A key to all five nominal species of Crossorhombus is provided.

Key words: Biodiversity, ichthyology, identification key, sexual dimorphism, taxonomy, western Pacific

Crossorhombus pescadores sp. nov., NMMB-P 42260, holotype, male, 99.8 mm SL, preserved.
A. Ocular side; B. Blind side.

Paratypes of Crossorhombus pescadores sp. nov., showing ocular sides (odd numbers) and blind sides (even numbers).
A. HUMZ 237066, immature male, 74.8 mm SL; B. NMMB-P 42263, female, 92.4 mm SL; C. NMMB-P 42262, immature female, 58.0 mm SL.

 Crossorhombus pescadores sp. nov

Diagnosis. A species of Crossorhombus differing from its congeners in having: caudal fin with light-gray band along posterior sub-margin; a pair of small black spots on band at upper and lower fourth rays, respectively; a bluish-black, horizontal triangular marking on blind side of body in male; a series of dark blotches along dorsal and ventral margins of body; combination of some meristic and proportional characters: large head; small upper and lower eyes; slightly longer pectoral-fin on ocular side; fewer dorsal- and anal- fin rays and fewer scales in lateral line and others.

Etymology. The specific name “pescadores” is the old name of the type locality, meaning “fishermen” in Portuguese. It is treated as a noun in apposition.

 Kunio Amaoka, Yo Su and Hsuan-Ching Ho. 2026. A New lefteye Flounder of the Genus Crossorhombus (Teleostei, Bothidae) from Penghu Islands, western Taiwan. ZooKeys. 1273: 15-25. DOI: doi.org/10.3897/zookeys.1273.167628 [13 Mar. 2026]

[Ichthyology • 2025] Pseudorhombus bahudaensis • Resolving the Pseudorhombus arsius cryptic species complex (Teleostei: Paralichthyidae): Phylogenetic Evidence and Description of A New Species

 

Pseudorhombus bahudaensis 

Acharya, Behera, Mohanty, Ray, Patro, Mishra & Mohapatra, 2025 

DOI: doi.org/10.11646/zootaxa.5711.3.4

Abstract

The Gangetic Largetooth flounder, Pseudorhombus arsius (Hamilton, 1822), long treated as a single Indo-Pacific species, represents a cryptic species complex. Using a combination of morphological, morphometric, and molecular data, we discovered a distinct lineage that warrants recognition as Pseudorhombus bahudaensis sp. nov. Phylogenetic analyses of COI sequences revealed multiple polyphyletic clades, with two well-supported groups corresponding to P. arsius and the new species. Divergence dating indicates a separation of approximately 17 million years despite extensive morphological overlap. Diagnosis of the new species is supported by vertebral counts, subtle scale morphology, and differences in the position of the lateral line relative to the eye. These findings highlight the importance of integrating genetic and morphological evidence in resolving cryptic flounder complexes and provide a basis for re-evaluating distribution records attributed to P. arsius across the Indo-Pacific.

Pisces, Pseudorhombus bahudaensis, Pseudorhombus arsius, cryptic species complex

Pseudorhombus bahudaensis sp. nov. 

Smrutirekha ACHARYA, Rajesh Kumar BEHERA, Swarup Ranjan MOHANTY, Dipanjan RAY, Shesdev PATRO, Subhrendu Sekhar MISHRA and Anil MOHAPATRA. 2025. Resolving the Pseudorhombus arsius cryptic species complex (Teleostei, Paralichthyidae): phylogenetic evidence and description of Pseudorhombus bahudaensis sp. nov. Zootaxa. 5711(3); 381-397. DOI: doi.org/10.11646/zootaxa.5711.3.4 [2025-10-20]

[Ichthyology • 2025] Integrated Molecular and Morphological Analyses Resolve Long-Standing Classification Challenges in the Sinistral Flatfish Family Bothidae (Teleostei: Carangiformes)

  

Bothidae Smitt, 1892
Taeniopsettidae Amaoka, 1969

Monolenidae  n. fam. 
Grammatobothidae n. fam. 

in Tongboonkua, Chanet et Chen, 2025. 

DOI: doi.org/10.1111/zsc.70020  

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ABSTRACT

The flatfish family Bothidae comprise 170 currently recognised species in 20 genera, classified under two subfamilies. Although previous morphological and molecular studies have supported the monophyly of the family, its intrafamilial relationships remain largely unexplored, and the monophyly of the 20 existing genera has yet to be thoroughly evaluated. This study aims to address these long-standing systematic issues, particularly at the generic level, and to elucidate the sister-group relationships within Bothidae using a comprehensive set of samples of 87 morphospecies across 19 genera, and DNA sequence data from two mitochondrial and three nuclear gene markers. Our results reveal that the subfamily Bothinae is paraphyletic with respect to monophyletic Taeniopsettinae. Additionally, ‘Bothinae’ can be subdivided into three main clades (Bothinae 1–3). At the generic level, while Grammatobothus is resolved as monophyletic (=Bothinae 1) and as the sister group to the remaining bothids, four other specious genera—Arnoglossus, Laeops, Parabothus, and Psettina—are not. To resolve these taxonomic inconsistencies, we integrate evidence from phylogeny, morphology, and biogeography. Consequently, we propose elevating Taeniopsettinae to family status, establishing two new families—Monolenidae (=Bothinae 2) and Grammatobothidae—each comprising a single genus, and restricting the family Bothidae to Bothinae 3. We also refine the usage of the valid generic names Arnoglossus (=Arnoglossus V), Laeops (=Laeops II), Parabothus (=Parabothus III), and Psettina (=Psettina III), and recommend the resurrection of previously synonymised bothid genera as well as the establishment of new genera. These taxonomic revisions are ongoing and will be elaborated upon in a forthcoming study.

Keywords: left-eyed flounder, morphology, multigene phylogeny, new family, Pleuronectoidei, systematics

Bothidae Smitt, 1892 

Taeniopsettidae Amaoka, 1969

Monolenidae  n. fam. Tongboonkua, Chanet & Chen, 2025

Type genus: Monolene Goode, 1880

Grammatobothidae n. fam. Tongboonkua, Chanet & Chen, 2025

Type genus: Grammatobothus Norman, 1926

 

Pakorn Tongboonkua, Bruno Chanet and Wei-Jen Chen. 2025. Integrated Molecular and Morphological Analyses Resolve Long-Standing Classification Challenges in the Sinistral Flatfish Family Bothidae (Teleostei: Carangiformes). Zoologica Scripta. DOI: doi.org/10.1111/zsc.70020 [25 September 2025]

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[Ichthyology • 2020] Typhlachirus lipophthalmus, A Rare Eye-less Sole from Sarawak, Malaysian Borneo (Teleostei: Soleidae)

 

  Typhlachirus lipophthalmus (Károli, 1882)

 from Sungai Kuap (Sarawak River basin)

in Tan & Grinang, 2020. 

 DOI:  10.23788/IEF-1150

An example of the eye-less sole, Typhlachirus lipophthalmus, was collected from a tidal section of the Sadong River in Sarawak, Malaysian Borneo, in January 2018. It is apparently the second known record of this species since its description in 1882. A description based on selected meristic and morphometric data gathered from the specimen, supported by radiographs and photographs of it, as well as notes on its capture and habitat, are presented.

 Fresh coloration of Typhlachirus lipophthalmus (right side), ZRC 59653. 61.2 mm SL, shortly after capture.

Live coloration of Typhlachirus lipophthalmus (ca. 15 cm total length) from Sungai Kuap (Sarawak River basin), showing both right (pigmented) and left side of the fish [copyright Chien Lee, first published in Atack (2006)].

Typhlachirus lipophthalmus (Károli, 1882)

 

Distribution. Typhlachirus lipophthalmus is presently known only from Sarawak, Malaysian Borneo, having been recorded from the lower reaches of Sungai Sadong of the Sadong River basin (Tan & Grinang, 2018 and present study) and from Sungai Kuap of the Sarawak River basin (Atack, 2006). The range of Typhlachirus lipophthalmus is expected to be wider, pending further surveys of estuarine habitats in Borneo. See Figure 7 for the distribution of all three species of Typhlachirus.

 Tan Heok Hui and Jongkar Grinang. 2020. Typhlachirus lipophthalmus, A Rare Eye-less Sole from Borneo (Teleostei: Soleidae). Ichthyological Exploration of Freshwaters. IEF-1150. DOI:  10.23788/IEF-1150

 pfeil-verlag.de/wp-content/uploads/2020/08/IEF-1150-www.pdf

[Ichthyology • 2022] Exon-capture Data and Locus Screening provide new insights into the Phylogeny of Flatfishes (Pleuronectoidei)

in Atta, Yuan, Li, ... et Tornabene, 2022.

  DOI: 10.1016/j.ympev.2021.107315

Highlights: 

• Phylogenetic analysis of flatfishes uses next-gen dataset with largest taxon sampling to date.

• Rhombosoleidae is found to be in Pleuronectoidea rather than Soleoidea.

• Positions of Poecilopsettidae and Scophthalmidae are dictated by tree-construction method.

• Many relationships in the flatfish tree are unstable due to periods of rapid evolution.

• 8/16 families need thorough analysis; 23/127 genera may not be monophyletic (21 not yet sampled).

Abstract

There is an extensive collection of literature on the taxonomy and phylogenetics of flatfishes (Pleuronectiformes) that extends over two centuries, but consensus on many of their evolutionary relationships remains elusive. Phylogenetic uncertainty stems from highly divergent results derived from morphological and genetic characters, and between various molecular datasets. Deciphering relationships is complicated by rapid diversification early in the Pleuronectiformes tree and an abundance of studies that incompletely and inconsistently sample taxa and genetic markers. We present phylogenies based on a genome-wide dataset (4,434 nuclear markers via exon-capture) and wide taxon sampling (86 species spanning 12 of 16 families) of the largest flatfish suborder (Pleuronectoidei). Nine different subsets of the data and two tree construction approaches (eighteen phylogenies in total) are remarkably consistent with other recent molecular phylogenies, and show strong support for the monophyly of all families included except Pleuronectidae. Analyses resolved a novel phylogenetic hypothesis for the family Rhombosoleidae as being within the Pleuronectoidea rather than the Soleoidea, and failed to support the subfamily Hippoglossinae as a monophyletic group. Our results were corroborated with evidence from previous phylogenetic studies to outline regions of persistent phylogenetic uncertainty and identify groups in need of further phylogenetic inference.

 

Keywords: Phylogenomics, Systematics, Soles, Flounders, Incomplete-lineage-sorting, Target-enrichment

Conclusions: 

Our analysis of flatfish systematics using an exon-capture dataset with relatively dense taxon sampling was mostly consistent with the leading phylogenetic hypotheses for the Pleuronectiformes (BHC model) and the Pleuronectidae (Vinnikov et al., 2018). We report a novel position for the family Rhombosoleidae and show extremely poor support for the subfamily Hippoglossinae. Collective inference using sixteen phylogenetic analyses demonstrates the tenuous nature of several flatfish relationships at various evolutionary scales, and how certain relationships are favored by particular methods. By examining our data within the historical context of flatfish systematics we were able to identify several regions where phylogenetic uncertainty is likely to remain and outline groups that should be targeted for further study.

 Calder J. Atta, Hao Yuan, Chenhong Li, Dahiana Arcila, Ricardo Betancur-R, Lily C. Hughes, Guillermo Ortí, Luke Tornabene. 2022. Exon-capture Data and Locus Screening provide new insights into the Phylogeny of Flatfishes (Pleuronectoidei). Molecular Phylogenetics and Evolution. 166,107315. DOI: 10.1016/j.ympev.2021.107315

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[Ichthyology • 2021] Systematic Revision of the Flatfish Genus Peltorhamphus Günther, 1862 (Pleuronectiformes: Rhombosoleidae), including Description of A New Species from Southeastern New Zealand, with Biological and Ecological Summaries for the Species

  Peltorhamphus novaezeelandiae Günther, 1862

in Munroe, 2021.

DOI: 10.11646/zootaxa.4905.1.1

Abstract

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.

Keywords: Pisces, New Zealand flatfishes, South Pacific flatfishes, taxonomy, species description, generic revision, synonymy, flatfish ecology, New Zealand Sole, Slender Sole, Speckled Sole, New Zealand Gray Sole

Thomas A. Munroe. 2021. 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. Zootaxa. 4905(1); 1-104. DOI: 10.11646/zootaxa.4905.1.1

[Ichthyology • 2018] Platichthys solemdali • A New Flounder Species (Actinopterygii, Pleuronectiformes) From the Baltic Sea

Platichthys solemdali 

Momigliano, Denys,  Jokinen & Merilä, 2018

  DOI: 10.3389/fmars.2018.00225

photo: Mats Westerbom 

The European flounder Platichthys flesus (Linnaeus, 1758) displays two contrasting reproductive behaviors in the Baltic Sea: offshore spawning of pelagic eggs and coastal spawning of demersal eggs, a behavior observed exclusively in the Baltic Sea. Previous studies showed marked differences in behavioral, physiological, and life-history traits of flounders with pelagic and demersal eggs. Furthermore, a recent study demonstrated that flounders with pelagic and demersal eggs represent two reproductively isolated, parapatric species arising from two distinct colonization events from the same ancestral population. Using morphological data we first established that the syntypes on which the original description of P. flesus was based belong to the pelagic-spawning lineage. We then used a combination of morphological and physiological characters as well as genome-wide genetic data to describe flounders with demersal eggs as a new species: Platichthys solemdali sp. nov. The new species can be clearly distinguished from P. flesus based on egg morphology, egg and sperm physiology as well as via population genetic and phylogenetic analyses. While the two species do show some minor morphological differences in the number of anal and dorsal fin rays, no external morphological feature can be used to unambiguously identify individuals to species. Therefore, we developed a simple molecular diagnostic test able to unambiguously distinguish P. solemdali from P. flesus with a single PCR reaction, a tool that should be useful to fishery scientists and managers, as well as to ecologists studying these species.

Family Pleuronectidae Rafinesque 1815

Genus Platichthys Girard 1854

Platichthys solemdali sp. nov.

  Baltic flounder

Diagnosis: Platichthys solemdali sp. nov. is diagnosable from P. stellatus by the absence of stripes on the dorsal and anal fin rays [Figures 6A, 2B; vs. presence of stripes for P. stellatus (Morrow, 1980)]. It can be distinguished with more than 99.999% certainty from P. flesus using genotypes of at least three of the outlier loci which were genotyped in this study (Loci 886, 3599, and 1822) by comparison with publically available reference data deposited in the Dryad digital repository (Momigliano et al., 2017a). P. solemdali sp. nov. (N = 50) has 46–59 dorsal fin rays vs. 51–66 for P. flesus recorded in this study, in Voronina (1999) and in Galleguillos and Ward (1982), and 35–41 anal fin rays vs. 35–45 in P. flesus from this study, Voronina (1999) and Galleguillos and Ward (1982). Hence, none of these meristic characters provide unambiguous species diagnosis. However, reproductive traits (viz. egg morphology and buoyancy, as well as sperm physiology) are unambiguous diagnostic characters. Eggs of P. solemdali sp. nov. become neutrally buoyant at salinities between 16 and 21.5 psu and are 0.99 ± 0.05 mm in diameter (Table 6; Figure 7), whereas the eggs of P. flesus in the Baltic Sea are larger (1.3–1.5 mm) and reach neutral buoyancy between 11 and 18 psu (Table 6; Nissling et al., 2002). Spermatozoa of P. solemdali sp. nov. activate at minimum salinities between 2 and 4 psu, in contrast to a required salinity above 10 psu for P. flesus (Table 7).

Geographic distribution:   P. solemdali sp. nov. is endemic to the Baltic Sea, where it has a wide distribution in coastal and bank areas across the region up to the Gulf of Finland and the southern Bothnian Sea. Confirmed individuals of P. solemdali sp. nov. have been sampled as far south as Öland (SD 27) (species identity confirmed via genetic analyses, Figure 1) and Hanö Bay (SD 25) (based on egg morphology, see Wallin, 2016; Nissling et al., 2017). In a recent paper Orio et al. (2017) suggested that environmental conditions in the entire southern Baltic Sea are suitable for demersal spawning flounders, and already Mielck and Künne (1935) reported ripe female flounders with small eggs from shallow low-saline (6–7‰) areas in the southern Baltic Sea (Oder Bank, SD 24). However, the current occurrence of P. solemdali sp. nov. in the southern regions is poorly known and, hence, it is still unclear whether the species is found throughout the coastal Baltic Sea area.

Habitat: P. solemdali sp. nov. lives in brackish water of varying salinities in the coastal zone at 0.5–50 m depth on soft and hard bottoms.

Etymology: This species is dedicated to Per Solemdal (1941–2016) who was the first researcher to study the Baltic Sea flounder's eggs and sperm in connection to salinity and discovered that “the specific gravity of the eggs is a fixed population characteristic which is almost unchangeable” (Solemdal, 1973) laying the foundations on which many subsequent studies on local adaptation and speciation of Baltic Sea marine fishes were built.

Paolo Momigliano, Gaël P. J. Denys, Henri Jokinen and Juha Merilä. 2018. Platichthys solemdali sp. nov. (Actinopterygii, Pleuronectiformes): A New Flounder Species From the Baltic Sea.  Frontiers in Marine Science.  DOI: 10.3389/fmars.2018.00225

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The first endemic Baltic Sea fish species received its name  phys.org/news/2018-07-endemic-baltic-sea-fish-species.html via @physorg_com

[Ichthyology • 2016] Redescriptions of Two Closely related East Asian Flatfish Species of the Genus Pleuronichthys, Pleuronichthys lighti & P. cornutus

(A–C) Pleuronichthys lighti Wu, 1929
(F–H) Pleuronichthys cornutus (Temminck & Schlegel, 1846)

DOI:  10.11646/zootaxa.4205.1.1  

Abstract

Because of the taxonomic confusion, including misapplication of their scientific names, resulting from the morphological similarity of two East Asian flatfish species, Pleuronichthys lighti Wu, 1929 and Pleuronichthys cornutus (Temminck & Schlegel, 1846), both species are redescribed, with particular emphasis on some new key characters. New common names are proposed for each species.

Keywords: Pisces, Pleuronichthys lighti, Pleuronichthys cornutus, redescription, morphology, scale

Pleuronichthys lighti Wu, 1929

(New English name: Common frog flounder)

Pleuronichthys cornutus (Temminck & Schlegel, 1846)

(New English name: Phantom frog flounder)

FIGURE 5. Ocular side coloration variations in fresh Pleuronichthys lighti (A–E) and P. cornutus (F–J).
A: BSKU 114101; B: BSKU 118425; C: BSKU 118426 (A–C were photographed by K. Yokogawa); D: KAUM–I. 20492; E: KAUM–I. 5064;
F, G: Uncatalogued specimens (F and G were photographed by K. Watanabe); H: KAUM–I. 30446; I: KAUM–I. 29267; J: KAUM– I. 4229 (KAUM specimens were photographed by the Kagoshima University Museum).

DOI:  10.11646/zootaxa.4205.1.1 

Kōji Yokogawa, Ken-Ichi Watanabe and Gota Ogihara. 2016. Redescriptions of Two Closely related East Asian Flatfish Species of the Genus Pleuronichthys.
  Zootaxa. 4205(1); DOI:  10.11646/zootaxa.4205.1.1 

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[Ichthyology • 2008] Symphurus thermophilus • A New Western Pacific Tonguefish (Pleuronectiformes: Cynoglossidae): The First Pleuronectiform discovered at active Hydrothermal Vents

Symphurus thermophilus  

  Munroe & Hashimoto, 2008

Abstract

Symphurus thermophilus n. sp., described from 16 specimens collected by submersibles, ROV, epibenthic sled and dredge, occurs on a variety of substrata at several active hydrothermal sites located at 239–733 m between 21°N and 35°S in the western Pacific Ocean. Symphurus thermophilus, the only pleuronectiform fish known to inhabit hydrothermal vent areas, is characterized by the combination of a 1–2–2–2–2 pattern of interdigitation of dorsal proximal pterygiophores and neural spines, 14 caudal-fin rays, 5 hypurals, 9 abdominal vertebrae, 47–51 total vertebrae, 88–94 dorsal-fin rays, 74–80 anal-fin rays, 100–112 scales in longitudinal series, ocular-side pigmentation pattern featuring 5–8, black, mostly incomplete crossbands, uniformly white blind side, and black peritoneum. Of specimens examined, seven including the holotype, were collected on Kaikata Seamount off southern Japan; one specimen was collected at the Kasuga-2 hydrothermal vent, Marianas Islands; and six were collected at sites on the Kermadec Ridge. In addition to specimens captured, many other S. thermophilus were observed from submersibles and ROVs at hydrothermal sites in the western Pacific including those in the Marianas Islands, at Nikko Seamount near Minami-Iohjima Island, and at Minami-Ensei Knoll, Mid-Okinawa Trough. Many of the specimens examined have skeletal anomalies including fused bones in the caudal skeleton, and missing or partially developed and/or misshapen fin rays.

Key words: flatfish, Symphurus, hydrothermal vents

Symphurus thermophilus    Munroe & Hashimoto, 2008 

FIGURE 3. Photographs of the hydrothermal vent tonguefish, Symphurus thermophilus. 
A. In situ photograph of S. thermophilus observed at Rumble 3 site, western Pacific, an area where this species occurs in high abundance. B. In situ photograph of S. thermophilus (most individuals <10 cm TL) observed at Daikoku Seamount, western Pacific, an area where this species occurs in high abundance. C. Photo of recently captured juvenile S. thermophilus taken at the Barnacle Boulders site at Kasuga-2, Mariana Islands. 

Figures 3A–C provided courtesy of NOAA’s Ocean Exploration Program and available from oceanexplorer.NOAA.gov  and oceanexplorer.NOAA.gov/explorations (Accessed 3 June 2008)

Thomas A. Munroe and Jun Hashimoto. 2008. A New Western Pacific Tonguefish (Pleuronectiformes: Cynoglossidae): The First Pleuronectiform discovered at active Hydrothermal Vents.  Zootaxa. 1839; 43–59.

  http://www.mapress.com/zootaxa/2008/f/zt01839p059.pdf

[Ichthyology • 2016] Cynoglossus nanhaiensis • A New Species of Tongue Sole (Pleuronectiformes: Cynoglossidae: Cynoglossus) from coastal waters of the South China Sea

Cynoglossus nanhaiensis 

Wang, Munroe & Kong, 2016

 DOI: 10.2988/0006-324X-129.Q2.129 

Abstract

A new tongue sole, Cynoglossus nanhaiensis, described from 21 specimens (101.0–133.7 mm SL) collected in coastal waters of the South China Sea, is distinguished from congeners by the following combination of characters: 3 ocular-side lateral lines; no blind-side lateral lines; 2 ocular-side nostrils; 8 caudal-fin rays; 49–51 total vertebrae; 64–73 scales in the midlateral line; 11–12 scales in diagonal series between midlateral and dorsal lateral lines; 99–108 dorsal-fin rays; 77–82 anal-fin rays; pores of lateral-line scales tubular, with conspicuously black tips posteriorly; and with light- to medium-brown ocular-side background coloration overlain by numerous, small, irregular, dark blotches forming a series of narrow, interrupted, longitudinal stripes, with many specimens also featuring two large, brown spots on their caudal region. Among congeners, C. nanhaiensis is most similar to C. maccullochi Norman, 1926, described from specimens taken off Queensland, Australia, but differs in its ocular-side pigmentation (conspicuous longitudinal series of irregular blotches and caudal spots absent in C. maccullochi) and body depth. Features of C. nanhaiensis are also reminiscent of those reported for C. dollfusi (Chabanaud, 1931), a poorly-known nominal species from the Red Sea, and C. itinus (Snyder, 1909), a better-known species occurring in marine waters off Japan and Southeast Asia. Cynoglossus nanhaiensis differs from both species in having two (vs. one) ocular-side nostrils. Cynoglossus itinus also lacks the series of conspicuous, darkly-pigmented, interrupted, longitudinal stripes on the ocular side that are characteristic of C. nanhaiensis. Cynoglossus nanhaiensis is further distinguished from C. dollfusi in having only a single pelvic fin (vs. two in C. dollfusi). Cynoglossus nanhaiensis occurs in coastal waters of the South China Sea off southern China and Viet Nam.

Keywords: Flatfish, Tonguefish, Cynoglossid tongue sole

Fig. 1. Cynoglossus nanhaiensis, new species, holotype (fresh condition), SCSMBC007425, male, 127.6 mm SL.
A. Ocular side. B. Blind side. (Photograph: Z.-M. Wang). 

Distribution.— Based on fishery landings, this species occurs in coastal waters off Sanya and Lingshui, Hainan Province; Zhanjiang, Guangdong Province, China; two specimens were collected off Viet Nam, one in the Gulf of Tonkin (20°46′29.99″N, 107°04′40.8″E) and the other off Phan Thiet (10°55′20″N, 108°06′34″E).

Etymology.— The name, nanhaiensis, is derived from the Chinese word, Nanhai, meaning South China Sea, in reference to localities where most specimens were collected.

Zhong-Ming Wang, Thomas A. Munroe and Xiao-Yu Kong. 2016. A New Species of Tongue Sole (Pisces: Pleuronectiformes: Cynoglossidae: Cynoglossus) from coastal waters of the South China Sea. Proceedings of the Biological Society of Washington. 129(1); 129-143. DOI: 10.2988/0006-324X-129.Q2.129