DOI: 10.3897/vz.76.e189837

Authors: Amanda K. Pinion, Daemin Kim, Elizabeth P. Dolan, David S. Portnoy, Gary Voelker, Kevin W. Conway

Abstract:

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DOI: 10.3897/vz.75.e156077

Authors: Amanda K. Pinion, Daemin Kim, Elizabeth P. Dolan, David S. Portnoy, Gary Voelker, Kevin W. Conway

Abstract: Combined analyses of molecular and morphological data support a revised classification of Notropis stramineus comprising five distinct evolutionary lineages, two for which names are available, Notropis stramineus (Cope, 1865) and N. missuriensis (Cope, 1871), herein redescribed, and three for which no names are available, here formally described as new species. Four of these clades comprise a species complex, here termed the N. stramineus species complex, while these four clades, in addition to N. procne, N. topeka, N. chihuahua and the fifth clade form a monophyletic group here termed the N. stramineus species group. Notropis lucifer sp. nov., sister taxon of N. chihuahua, is distributed in the Colorado River and Rio Grande basins of Texas (USA), where it is distributed in the Devils River, and presumably also in Pinto Creek; based on distribution, populations in tributaries of the Rio Grande in Mexico are tentatively also assigned to this species. Notropis lucifer sp. nov. can be distinguished from other members of the N. stramineus species group primarily by coloration in life and pigmentation patterns which are still visible after preservation. Notropis oblitus sp. nov. is found in several Gulf Slope streams in Texas, including the upper reaches of Nueces, San Antonio, and Guadalupe River basins, though likely absent from the Colorado River basin. This species can be distinguished from other members by head shape, eye size and pigmentation patterns. Notropis multicorniculatus sp. nov. is found in the western portions of the Arkansas, Canadian and Red River basins in parts of Texas, Oklahoma, and Kansas, and likely also Arkansas and Colorado, as well as the Pecos River (New Mexico), where it is likely non-native. This species can be distinguished from other members of the species complex by comparatively larger and more abundant tubercles in males and differences in body shape. Comments are provided regarding the genus Miniellus, which has been recently suggested to comprise 21 species, including N. stramineus.

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DOI: 10.3897/vz.75.e155717

Authors: Rajeev Raghavan, Remya L. Sundar, C.P. Arjun, Arya Sidharthan, Nithinraj Panangattu Dharmarajan, Appukuttannair Biju Kumar, Siby Philip, Anvar Ali, Mandar S. Paingankar, Glavin Thomas Rodrigues, Ralf Britz, Neelesh Dahanukar

Abstract: Abstract Subterranean biodiversity continues to be poorly known as a result of uncertainties, challenges and hazards associated with sampling in microhabitats such as aquifers and caves. Focusing on the narrow, lateritic aquifers and associated groundwater habitats in the Western Ghats freshwater ecoregion (southern peninsular India), we investigate the genetic diversity of an enigmatic group of eel-like fishes (family Synbranchidae). A maximum-likelihood phylogenetic analysis based on mitochondrial cytochrome oxidase subunit 1 (cox1) gene sequences recovered these synbranchid eels into two distinct clades comprising genera Ophichthys (fossorial eels ‘with eyes’) and Rakthamichthys (aquifer-dwelling ‘blind’ eels). Additionally, three species-delimitation approaches (based on the mitochondrial cox1 gene), revealed the presence of 11 Evolutionarily Distinct Lineages (EDLs) within Rakthamichthys separated by an inter-lineage divergence between 5.8–20.3%, and an intra-lineage divergence between 0–4.5%. Rakthamichthys in southern peninsular India exhibited a distribution pattern comprising both restricted-range and wide-ranging lineages. Fossorial eels of the genus Ophichthys, on the other hand, are widely distributed in southern peninsular India, with clear geographical boundaries separating the two known species. The genetic network of Rakthamichthys and Ophichthys revealed multiple haplotypes within various EDLs, with a large number of mutations separating the haplotypes within, and between species and/or lineages. Though represented by high levels of genetic divergence revealing the potential existence of at least 11 EDLs, their remarkable morphological uniformity combined with a complex distribution pattern makes it difficult to assign known species names to various Rakthamichthys lineages. Most subterranean habitats in southern peninsular India are under severe anthropogenic threats. Therefore, resolving the taxonomy of, and developing conservation actions for groundwater-dependent species is a priority, for which we suggest future steps.

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DOI: 10.3897/vz.75.e126067

Authors: Shing-Lai Ng, Nicolas Straube, Kwang-Ming Liu, Shoou-Jeng Joung

Abstract: Abstract The shark genus Etmopterus is the most species-rich shark genus, however, several of its species level taxa pose taxonomic challenges. Especially the Etmopterus lucifer species group is in need of a taxonomic re-evaluation. In the present study, we review the status of E. lucifer and E. molleri from the north- and southwestern Pacific applying an integrative taxonomic approach. Our dataset comprises 100 morphological characters and the mitochondrial NADH2 marker (1,010 bp) for 178 and 83 specimens, respectively. Our results show that E. lucifer and E. molleri from the Northwestern Pacific are distinct from specimens sampled in the Southwestern Pacific. We therefore (1) resurrect E. abernethyi for specimens in the southwestern Pacific hitherto assigned to E. lucifer, (2) synonymize the Northwestern Pacific E. burgessi with E. lucifer and (3) resurrect E. schmidti for specimens in the Northwestern Pacific hitherto assigned to E. molleri. A lectotype is designated herein for E. lucifer. Redescriptions of the four valid species, E. abernethyi, E. lucifer, E. molleri, and E. schmidti, are given and an updated key to all members of the E. lucifer group from the central Indo-Pacific is provided. The current division of the E. lucifer subgroups is challenged, as the key character, the relative length of flank-marking branches, shows great intraspecific variation.

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DOI: 10.3897/vz.74.e130038

Authors: George M.T. Mattox, Flávio C. T. Lima, Ralf Britz, Camila S. Souza, Claudio Oliveira

Abstract: Abstract The miniature fish genus Priocharax currently comprises seven valid species: P. ariel, P. britzi, P. marupiara, P. nanus, P. pygmaeus, P. toledopizae and P. varii. Except for P. ariel and P. pygmaeus, all the species are endemic to Brazil. Priocharax is characterized by several paedomorphic features such as reductions in the laterosensory system, number of fin rays, and ossification of parts of the skull. The most striking reductive character of Priocharax is the larval rayless pectoral fin in which most of its ossified endoskeletal elements are absent. We describe herein two new species of Priocharax from the vicinity of Santarém municipality, Pará state, Brazil. Both new species are distinguished from each other and from congeners by a combination of morphological features (i.e., osteological, morphometric, and meristic data) and molecular information (i.e., DNA barcode). We also present an updated maximum likelihood tree which now includes all nine species of Priocharax.

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DOI: 10.3897/vz.74.e113955

Authors: Kyoji Fujiwara, Hiroyuki Motomura, Adam P. Summers, Kevin W. Conway

Abstract: Abstract Rhinolepadichthys, a new genus of the gobiesocid subfamily Diademichthyinae, is described for the “Lepadichthys” lineatus complex (including Rhinolepadichthys geminus comb. nov., R. heemstraorum comb. nov., R. lineatus comb. nov., and R. polyastrous comb. nov.). Detailed investigation of external morphology and osteological anatomy of the new genus and related genera suggests that Rhinolepadichthys represents the sister genus to Discotrema, based on the following putative synapomorphies: (1) presence of a hardened (potentially keratinized) cap on the surface of at least some disc papillae (vs. surface of disc papillae soft, without hardened cap); and (2) the anterolateral part of the ventral postcleithrum extended anteriorly as a well-developed rod-like process, its tip close to the base of pelvic-fin soft ray 4 (vs. only weakly pointed, or irregular). Compared with Discotrema, Rhinolepadichthys gen. nov. is distinguished by the presence of a row of 8–12 large papillae on the inner surface of the upper and lower lips (vs. inner surface of lips smooth, without distinct papillae); the absence (vs. presence) of a well-developed lateral process on the pterotic immediately posterior to the opening of the otic canal; the presence (vs. absence) of gill rakers on the anterior edge of ceratobranchials 1–3; the presence (vs. absence) of gill rakers on the posterior edge of ceratobranchial 4; having the upper pharyngeal teeth arranged in a loose patch on the ventral surface of the pharyngobranchial 3 toothplate, with tooth tips directed posteroventrally (vs. arranged in a single row along posteroventral edge of the pharyngobranchial 3 toothplate, with tooth tips directed posteriorly); features of the adhesive disc, including outline of disc papillae roughly hexagonal or ovoid and with a flattened surface (vs. outline circular, at least some with raised, dome-like surface); the absence (vs. presence) of a deep cavity at the center of disc region C; the absence (vs. presence) of three paired and one median cluster of small papillae (reminiscent of bunches of grapes) across the surface of the adhesive disc; and having the ventral postcleithrum entire, not divided into two separate, articulating elements (vs. ventral postcleithrum divided into an anterior and posterior element, separated via a specialized joint). Reexamination of materials of the poorly known genus Unguitrema, considered a close relative of Discotrema, revealed no morphological differences between the two genera. Unguitrema therefore represents a junior synonym of Discotrema.

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DOI: 10.3897/vz.73.e110875

Authors: Heok Hee Ng, Maurice Kottelat

Abstract: Abstract Mystus celator sp. nov. is described from the Irrawaddy River drainage in northern Myanmar. It can be distinguished from congeners in having a combination of: three equally dark longitudinal stripes separated by two pale interspaces on sides of body; round, dark tympanic spot; ovoid, dark spot on caudal peduncle; length of adipose-fin base 18.0–23.3% SL; angle of predorsal profile 21–24°; posterior cranial fontanelle not reaching base of supraoccipital process; 25–30 rakers on the first branchial arch; and 35–36 vertebrae. The identity of Mystus pulcher is fixed with the designation of a lectotype.

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DOI: 10.3897/vz.73.e97515

Authors: Harald Ahnelt, Oliver Macek, Vanessa Robitzch

Abstract: Species of the gobiid genus Schindleria are among the smallest and fastest reproducing vertebrates of the oceans. We describe a new species, Schindleria qizma, from the Red Sea, Saudi Arabia. It is an extreme example of progenesis, within the already paedomorphic genus, with morphological traits clearly differentiating it from its congeners. Schindleria qizma has a unique, unflexed notochord with a straight urostyle of which the tip is inserted into the hypural cartilage, rather than the typical flexed notochord with an upturned urostyle of the other species of Schindleria. Schindleria qizma belongs to the short dorsal-fin type of Schindleria. It is further characterized by an elongated but relatively deep body; a short dorsal fin originating just slightly anterior to the anal fin (predorsal-fin length 59.4% of SL vs. preanal-fin length 60.2% of SL); a head continuously increasing in depth posteriorly with a straight dorsal profile; a short snout (18.6% of head length); large eyes (34.4% of head length); a short pectoral-radial plate (6.3% of SL); 13 dorsal-fin rays; 11 anal-fin rays; 0–2 procurrent rays (where the last procurrent ray is short, if present); an anal fin with the first anal-fin ray situated opposite the second dorsal-fin ray; toothless oral jaws; females with few (10–11, total) but very large (4.6% of SL) eggs and with a conspicuous urogenital papilla characterized by a wide urogenital opening flanked by two long, bilobed projections; a dorsally pigmented swim-bladder; blackish, iridescent eyes, capped by a silvery layer with irregular rows of black dots or blotches; and no additional external pigmentation on its body, at least in preserved specimens.

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DOI: 10.3897/vz.73.e101011

Authors: Neelesh Dahanukar, Remya L. Sundar, Duwaki Rangad, Graham Proudlove, Rajeev Raghavan

Abstract: The world’s largest subterranean fish was discovered in 2019, and was tentatively identified as a troglomorphic form of the golden mahseer, Tor putitora. Detailed analyses of its morphometric and meristic data, and results from molecular analyses now reveal that it is a new species of the genus Neolissochilus, the sister taxon of Tor. We formally describe the new species as Neolissochilus pnar, honouring the tribal communities of East Jaintia hills in Meghalaya, Northeast India, from where it was discovered. Neolissochilus pnar possesses a number of characters unique among species of Neolissochilus, with the exception of the similarly subterranean N. subterraneus from Thailand. The unique characters that diagnose N. pnar from all epigean congeners comprise highly reduced eye size to complete absence of externally visible eyes, complete lack of pigmentation, long maxillary barbels, long pectoral-fin rays, and scalation pattern. Neolissochilus pnar is distinguished from the hypogean N. subterraneus, the type locality of which is a limestone cave ~2000 kms away in Central Thailand, by a lesser pre-pelvic length (47.8–49.4 vs. 50.5–55.3 %SL), a shorter caudal peduncle (16.1–16.8 vs. 17.8–23.7 %SL), and shorter dorsal fin (17.4–20.8 vs. 21.5–26.3 %SL). In addition, Neolissochilus pnar is also genetically and morphologically distinct from its close congeners with a raw genetic divergence of 1.1–2.7% in the COI gene with putative topotype of N. hexastichus and 2.1–2.6% with putative topotype of N. hexagonolepis.

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DOI: 10.3897/vz.73.e98367

Authors: Rajeev Raghavan, Remya L. Sundar, C.P. Arjun, Ralf Britz, Neelesh Dahanukar

Abstract: The lateritic aquifers of the southern Indian state of Kerala harbour a unique assemblage of enigmatic stygobitic fishes which are encountered very rarely, only when they surface during the digging and cleaning of homestead wells. Here, we focus on one of the most unusual members of this group, the catfish Horaglanis, a genus of rarely-collected, tiny, blind, pigment less, and strictly aquifer-residing species. A six-year exploratory and citizen-science backed survey supported by molecular phylogenetic analysis reveals novel insights into the diversity, distribution and population structure of Horaglanis. The genus is characterized by high levels of intraspecific and interspecific genetic divergence, with phylogenetically distinct species recovered above a 7.0% genetic-distance threshold in the mitochondrial cytochrome oxidase subunit 1 gene. Contrasting with this deep genetic divergence, however, is a remarkable stasis in external morphology. We identify and describe a new cryptic species, Horaglanis populi, a lineage that is the sister group of all currently known species. All four species are represented by multiple haplotypes. Mismatch distribution reveals that populations have not experienced recent expansions.

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DOI: 10.3897/vz.73.e97922

Authors: Ralf Britz, George M. T. Mattox, Kevin W. Conway

Abstract: We compare the ontogeny of the hyopalatine arch in representatives of the Otophysi to shed light on the homology of the so-called quadrate-metapterygoid fenestra, QMF. Described initially as a character of characiforms (tetras and allies), presence of a QMF has also been reported for cobitid loaches and a handful of cyprinids among cypriniforms, as well as for a few clupeoids. In characiforms the QMF is either already present as an opening in the palatoquadrate cartilage in the earliest developmental stages we studied, or it forms later in the cartilage by resorption of chondrocytes. Some characiforms may lack a QMF during all stages of development. In cobitids the so-called QMF develops after the bones have ossified and forms mainly by resorption of bone tissue of quadrate and metapterygoid. Previous reports of a QMF in cyprinids are erroneous and the opening in this area forms by spatial separation of the quadrate and metapterygoid from the symplectic and not by the formation of a fenestra in the palatoquadrate cartilage. We suggest referring to this type as a quadrate-metapterygoid gap, QMG. Presence of a QMF in the palatoquadrate cartilage is a putative synapomorphy of characiforms. Development of a QMF by bone resorption in the ossified palatoquadrate is a putative synapomorphy of Cobitidae. A QMG is variously present and developed to different degrees in opsariichthyine and danionine cyprinids. A QMF is also present in several clupeoids and deserves further study.

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DOI: 10.3897/vz.72.e85144

Authors: Kole M. Kubicek

Abstract: Abstract The skeleton of Siluriformes is characterized by several autapomorphies, including secondary absence, extreme modification, and purported fusion of several ossifications. Although well documented in adults, information on skeletal development in catfishes is relatively sparse and typically focused on particular regions of the skeleton (e.g., Weberian apparatus). To further our understanding of the siluriform skeleton, I document the development of the entire skeleton in two ictalurid species, Ictalurus punctatus (channel catfish) and Noturus gyrinus (tadpole madtom) from five days pre-hatch to adult. I reexamine the homologies of bones previously hypothesized to represent compound elements in catfishes as well as an additional element only known to occur in some ictalurids. Development of the skeleton is complete in I. punctatus at 22.4 mm SL and almost complete in N. gyrinus (except dorsal- and anal-fin distal radials) at 14.1 mm SL. No signs of ontogenetic fusion were observed in any of the purported compound elements. Previous hypotheses of the homology of these elements and of additional ossifications are reviewed in light of developmental information obtained herein. No dermal parietal component is present at any stage in the so-called parieto-supraoccipital. The bone is the supraoccipital which ossifies from two lateral centers of ossification which later fuse, rather than from a median center. The ‘posttemporo-supracleithrum’ originates from a single center of ossification and represents the supracleithrum. The posttemporal is present in ictalurids and many other catfishes as a canal-bearing bone between the supracleithrum and the pterotic, a bone sometimes identified as the extrascapular. The extrascapular is missing in catfishes. Ictalurids have an additional dermal bone above the posttemporal, which is either an independently ossifying fragment of the posttemporal or a neoformation restricted to some members of this family. The single chondral bone of the pectoral girdle originates from a single center of ossification that represents the coracoid. The scapula is missing in catfishes. Dorsal-fin distal radial 2 is absent in catfishes and the foramen of dorsal-fin spine 2 is formed from modifications to the base of the fin-ray itself. Unlike loricarioid catfishes, the urohyal of ictalurids originates solely as an ossification of the sternohyoideus tendons. The anteriormost infraorbital element ossifies from a single center of ossification around the infraorbital sensory canal and represents the lacrimal. The antorbital is missing in catfishes. Finally, skeletal development of I. punctatus is compared to that available for other otophysans, including the cypriniforms Danio rerio and Enteromius holotaenia and the characiform Salminus brasiliensis.

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DOI: 10.3897/vz.72.e84983

Authors: Ingmar Werneburg, Uwe Hossfeld, Georgy S. Levit

Abstract: Here we report on a recently discovered student script of a lecture on paleontology given by Ernst Haeckel (1834–1919). The script dates to the summer semester of 1866, comprises 63 pages, and provides an overview of fossil invertebrate and mainly fossil vertebrate taxonomy and anatomy. It can be assumed that Russian student Nikolai Nikolajevitch Miklucho-Maclay (1846–1888), who later became a famous ethnologist, did not follow up on the lecture, but took the content directly from the lecture and from the blackboard in his notes. Hence, the drawings by Miklucho allow direct insight into Haeckel’s visualization of paleontology in the 1860s. We place the transcript in the historical context of understanding paleontology in the second half of the 19th century and address the break between zoology and embryology on the one hand and paleontology on the other, which is typical for Germany, partly persisting to this date. For that, we illustrate Haeckel’s integration of paleontology as part of a holistic triad, with fossil research gradually taking a back seat to zoology and embryology over the decades.

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DOI: 10.3897/vz.72.e79401

Authors: Harald Ahnelt, Vanessa Robitzch, Mohamed Abu El-Regal

Abstract: Abstract We describe a new, tiny species of Schindleria from a reef lagoon in the Red Sea off the coast of Hurghada, Egypt. Schindleria edentata, new species, belongs to the short dorsal-fin type of Schindleria, with the dorsal and anal fins of about equal length. Schindleria edentata is characterized by an elongated but relatively deep body (body depth at anal-fin origin 10.8% of SL and at 4th anal-fin ray 10.9 % of SL); a short dorsal fin originating just slightly anterior to the anal fin (predorsal-fin length 60.9% of SL, pre-anal fin length 64.8% of SL); a stubby head with a steep frontal profile, a short snout (i.e., 23.1% of head length), and large eye (i.e., 27.7% of the head’s length); a long pectoral radial plate (length 7.6% of SL); four dorsal and four ventral procurrent caudal-fin rays increasing in length posteriorly; last procurrent ray simple without additional spine and, although the longest, not distinctly elongate; 15 dorsal-fin rays; 13 anal-fin rays; the base of the first anal-fin ray positioned below the base of the third dorsal-fin ray; upper and lower jaws toothless; in vivo with translucent body; eye black; swim bladder capped by a melanophore blotch; no pigmentation externally on body after preservation.

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DOI: 10.3897/vz.72.e84274

Authors: Peter Johnston

Abstract: Anatomical features that have not been previously described in Latimeria were sought in histological section series, tissue-stained microCT scans, MRI scans, and synchrotron scan series. The spiracular organ, ultimobranchial endocrine gland, and m. cucullaris were identified in the expected locations. In addition, a muscle arising on the medial side of the pectoral girdle is identified and compared with a muscle in a similar location that attaches to the cranial rib in lungfish; these are proposed as homologues of the tetrapod m. omohyoideus. These findings are placed in evolutionary context by comparison with selected other groups of fish, lungfish and tetrapods. The position of Latimeria as a key taxon in the fish-to-tetrapod transition is emphasised by these findings, and the findings have potential to inform research on cranial structure in extinct taxa.

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DOI: 10.3897/vz.72.e84732

Authors: Manuel Andreas Staggl, Daniel Abed-Navandi, Jürgen Kriwet

Abstract: Elasmobranchs, comprising sharks, skates, and rays, have a long evolutionary history extending back into the Palaeozoic. They are characterized by various unique traits including a predominantly cartilaginous skeleton, superficial prismatic phosphatic layer, and permanent tooth replacement. Moreover, they exhibit a more or less marked sexual dimorphism. Especially the morphology of the chondrocranium and the elements of the whole cranial region of extant and extinct chondrichthyans can provide valuable information about corresponding functions, e.g. the feeding apparatus might reflect the diet of the animals. However, studies on sexual dimorphisms are lacking in orectolobiform sharks, therefore, little is known about possible sexual dimorphic characters in the cranial region in this group. For this reason, we present in this study a comprehensive morphological description of the cranial region of the brownbanded bamboo shark Chiloscyllium punctatum Müller & Henle, 1838, with a special focus on its sexual dimorphic characters. Our results reveal clear morphological differences in both sexes of the examined C. punctatum specimens, particularly in the chondrocranium and the mandibular arch. The female specimen shows a comparatively more robust and compact morphology of the chondrocranium. This pattern is also evident in the mandibular arch, especially in the palatoquadrate. The present study is the first to describe the morphology of an orectolobiform shark species in detail using both manual dissection and micro-CT data. The resulting data furthermore provide a starting point for pending studies and are intended to be a first step in a series of comparative studies on the morphology of the cranial region of orectolobiform sharks, including the determination of possible sexual dimorphic characteristics.

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DOI: 10.3897/vz.71.e71886

Authors: George M. T. Mattox, Kevin W. Conway

Abstract: Miniaturization, the evolution of extremely small adult body size, is a common phenomenon across the lineages of freshwater fishes, especially in the Neotropics where over 200 species are considered miniature (≤26 mm in standard length [SL]). Close to 30% of all miniature Neotropical freshwater fishes belong to the family Characidae, several of which are of uncertain phylogenetic placement within the family. We investigate the skeletal anatomy of Tucanoichthys tucano, a species of uncertain phylogenetic position from the upper Rio Negro basin, reaching a maximum known size of 16.6 mm SL. The skeleton of Tucanoichthys is characterized by the complete absence of ten skeletal elements and marked reduction in size and/or complexity of others, especially those elements associated with the cephalic latero-sensory canal system. Missing elements in the skeleton of Tucanoichthys include those that develop relatively late in the ossification sequence of the non-miniature characiform Salminus brasiliensis, suggesting that their absence in Tucanoichthys can be explained by a simple scenario of developmental truncation. A number of the reductions in the skeleton of Tucanoichthys are shared with other miniature characiforms, most notably species of Priocharax and Tyttobrycon, the latter a putative close relative of Tucanoichthys based on molecular data.

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DOI: 10.3897/vz.71.e62814

Authors: Pradeep Kumkar, Manoj Pise, Pankaj A. Gorule, Chandani R. Verma, Lukáš Kalous

Abstract: The hill stream loach genus Indoreonectes is endemic to peninsular India south of the Satpura hill ranges and is represented by three species I. evezardi, I. keralensis and I. telanganaensis. Indoreonectes evezardi has been suggested as a species complex based on recent genetic studies; however, due to lack of type material the species delimitation has been difficult. Here we redescribe I. evezardi collected from its type locality and describe two new species from the northern Western Ghats of India. Indoreonectes neeleshi, described from Mula River tributary of Godavari river system, can be diagnosed from all its congeners based on a combination of characters: inner rostral barbel reaching middle of nostril; maxillary barbel reaching midway between eye and posterior border of operculum; dorsal hump behind nape; bars on lateral side of the body wider than inter-bar space; total vertebrae 35 and dorsal fin insertion between 13th and 14th abdominal vertebrae. Indoreonectes rajeevi, described from Hiranyakeshi River of the Krishna river system, differs from all its congeners based on a combination of characters: inner rostral barbel reaching anterior margin of eye; maxillary barbel reaching posterior border of operculum; conspicuous black markings on lower lip, dorsal hump absent; total vertebrae 36 and dorsal fin insertion between 12th and 13th abdominal vertebrae. Further, I. neeleshi differs from its congeners by the raw genetic distance of 6.8–14.4% for the cox1 gene and 5.7–16.2% for the cytb gene, while I. rajeevi differs from its congeners by the raw genetic distance of 10.9–14.0% for the cox1 gene and 11.8–15.8% for the cytb gene.

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