Ophichthys hodgarti ( Chaudhuri 1913 )

Mukherjee, Nilanjan, Kumar, Rahul G. & Narayanan, Surya, 2025, Rediscovery and phylogenetic position of Moringua hodgarti Chaudhuri, 1913 (Synbranchiformes: Synbranchidae) from the Siang Valley of Arunachal Pradesh, India, Zootaxa 5636 (3), pp. 551-565 : 554-561

publication ID

https://doi.org/10.11646/zootaxa.5636.3.9

publication LSID

lsid:zoobank.org:pub:D6191F16-56D4-471E-B5E6-619547152140

DOI

https://doi.org/10.5281/zenodo.15576613

persistent identifier

https://treatment.plazi.org/id/555E6F06-2318-5062-BF95-6F70FEA0FF5C

treatment provided by

Plazi

scientific name

Ophichthys hodgarti ( Chaudhuri 1913 )
status

 

Ophichthys hodgarti ( Chaudhuri 1913)

Material examined

Syntypes: ZSI F7834/1 (177 mm TL), F7838/1 (211 mm TL); Upper Rotung , 2000 ft, Arunachal Pradesh, India. Collected by: D.S.W. Kemp, Abor Expedition, January 1912 .

Additional specimens: NCBS NRC-AA-9307–12. 6 ex., 179.3–253.7 mm TL. 28°39’16.76”N, 94°59’10.08”E, 685 m AMSL, near Ramsing village , Upper Siang district, Arunachal Pradesh, India. Collected by: Nilanjan Mukherjee, April 2022 GoogleMaps .

NCBS NRC-AB-0024–28. 5 ex., 157.7–230.8 mm TL. 28°39’16.76”N, 94°59’10.08”E, 685 m AMSL, near Ramsing village , Upper Siang district, Arunachal Pradesh, India. Collected by: Nilanjan Mukherjee, October 2022 GoogleMaps .

NCBS NRC-AA-9313. 1 ex., 83.7 mm TL. 28°8’36.29”N, 95°10’31.15”E, 395 m AMSL, near Rotung village , East Siang district Arunachal Pradesh, India. Collected by: Nilanjan Mukherjee & Rahul G. Kumar, October 2022 GoogleMaps .

Uncatalogued (cleared and stained). 1 ex., 157.7 mm TL. 28°39’16.76”N, 94°59’10.08”E, 685 m AMSL, near Ramsing village , Upper Siang district, Arunachal Pradesh, India. Collected by: Nilanjan Mukherjee, October 2022 GoogleMaps .

Diagnosis

Ophichthys hodgarti belongs to the genus Ophichthys because it shares with the other species a highly derived modified gill arch skeleton in which epibranchial 1, pharyngobranchial 2 and the interarcual bone are absent. It is distinguished from all other species of Ophichthys except O. ichthyophoides in possessing paired gill openings (vs single U-shaped gill opening). Ophichthys hodgarti can be distinguished from O. cuchia and O. terricolus in possessing fewer pre-anal (72–76 vs 95–100 in O. cuchia and 79 or 80 in O. terricolus ) and total vertebrae (117–122 vs 166–188 in O. cuchia and 144–149 in O. terricolus ). Ophichthys hodgarti can be additionally distinguished from O. desilvai and O. fossorius in possessing fewer caudal (45 or 46 vs 65–67 in O. desilvai and 52–58 in O. fossorius ) and total vertebrae (117–122 vs 140–142 in O. desilvai and 126–129 in O. fossorius ), and additionally from O. desilvai in a more posteriorly located vent (preanal length 74.9–79.3 %TL vs 68.9–71 %TL); and from O. indicus in possessing fewer pre-anal (72–76 vs 93–99) and total vertebrae (117–122 vs 137–144). Ophichthys hodgarti is closest in appearance to O. ichthyophoides , but can be distinguished from it by the body colouration of adult specimens being mottled with black (vs olive brown without mottling), by presence of scales over the entire body behind head (vs scales only extending anteriorly to middle of the body dorsally), a shorter preanal length (74.9–79.3% vs 79–80% TL) correlated with fewer preanal vertebrae (72–76 vs 79–82).

Description

Based on freshly collected specimens (n=12; 157.7–253.7 mm TL). See Figures 3 View FIGURE 3 , 4 View FIGURE 4 , 5 View FIGURE 5 and 6 View FIGURE 6 for general appearance and morphology and Table. 1 View TABLE 1 for morphometric data. Body slender and eel-like, nearly round in cross-section from behind head (Body depth (BD)/Body width (BW) 1–1.1) to anus (BD/BW 1–1.3), more laterally compressed near tail. Head length 5.6–7.5 %TL, snout rounded, upper jaw slightly longer. Eyes small, covered by skin, situated anterior to articulation of the jaws. Anterior naris on tip of snout, posterior naris situated above anterior third of eye; anterior to posterior narial distance 20.5–29.3 % HL. Upper lip overhangs lower, latter not visible in dorsal view. Skin on gular region smooth, not produced into longitudinal furrows. Gill membranes fused at isthmus, forming separate paired ventrolateral gill openings on either side of head. Small cycloid scales covering entire body, more prominent along posterior half. Vent located at 74.9–79.3% TL. Tip of tail rounded in lateral view, with fleshy dorsal and ventral fin folds, more prominent in juvenile specimens.

Gill Arch Osteology ( Fig.7 View FIGURE 7 )

Basihyal stout, slightly expanded at the anterior end and fused with basibranchial 1. Basibranchial 2 small, elongate in dorsal view, tightly sutured to basibranchial 1. Hypobranchial 1 elongate, wider at articulation with basibranchial 2, tapering posteriorly. Ceratobranchial 1 spatially removed from hypobranchial 1 and aligned with hypobranchial 2 and ceratobranchial 2. Epibranchial 1, and pharyngobranchial 2 absent. Hypobranchial 2 elongate, slightly expanded at anterior tip, with the posterior tip in close contact with ceratobranchial 1. Hypobranchial 3 stout, nearly square in outline, with a triangular process on the anterior face and not sutured to its antimere in ventral midline. Ceratobranchials 2, 3, 4 present as sequentially longer elements, with ceratobranchial 4 almost twice as long as ceratobranchial 2. Ceratobranchial 5 with tooth plate, bearing recurved conical teeth. Epibranchial 2 small, slender, slightly wider at articulation with ceratobranchial 2 and tapering distally; epibranchial 3 elongate, wider at articulation with ceratobranchial 3 and tapered distally; epibranchial 4 about twice as long as epibranchial 3, of nearly constant width throughout. Pharyngobranchial 3 spoon-shaped, narrow at proximal end, widening distally; teeth not discernable in the examined individual. Upper pharyngeal tooth plate 4 with approximately 9–10 conical, recurved teeth, decreasing in size towards the articulation with epibranchial 4.

Colouration in life and preservative

Dorsum dark brown ( Fig. 6 View FIGURE 6 ) fading to dirty grey ventrally, entire body mottled with black spots and blotches, more prominent on the sides and ventral surface. One individual from Ramsing was nearly white in colour, mottled with black. The juvenile topotype from Rotung is uniformly brown throughout, with the mottling not very distinct. Specimens in preservative are grey, and the mottling is more prominent. The syntypes are now uniformly light tan, with no evidence of mottling, although the illustrations in Chaudhuri (1913) depict mottling, suggesting it was present at the time of drawing.

Distribution, ecology and natural history

Ophichthys hodgarti is currently known only from the Siang Valley , Arunachal Pradesh, India. The type series was collected from streams at Upper Rotung 395 m AMSL. We collected additional specimens from near Ramsing , 685 m ASL, at an aerial distance of about 60 km. Both locations are part of the Siang River basin, which merges with the Brahmaputra River in the Assam plains south of Pasighat. At Rotung, O. hodgarti were observed amongst mud and gravel adjacent to irrigation channels flowing through agricultural fields. When disturbed, they rapidly burrowed into the substrate, outpacing a man digging with a shovel, and evading nearly all attempts at collection.

At Ramsing, all individuals were encountered adjacent to a first-order stream flowing through secondary forest, across a mud track and entering mixed agriculture fields ( Fig. 8A View FIGURE 8 ). They were observed at night, actively foraging in a nearly dry cemented drain that diverted water from the stream away from the road during the monsoons. During the day, they could only be found by digging into the substrate of gravel and mud adjacent to streams. The fish were never seen in the main channel of the stream, but only on the wet mud and leaf litter adjacent to the water. When disturbed, they dived headfirst into mud, to depths of over 20 cm. One individual was found on a mud track about 20 m away from the stream, the intervening ground covered in wet leaf litter. A female specimen collected at Ramsing, measuring 253.7 mm TL, was found to be gravid upon examination.

Some individuals regurgitated unidentified insect larvae and worms shortly after capture. Two individuals of Ophichthys hodgarti were placed in an aquarium for observation over a period of 48 h. The aquarium was furnished with a layer of soft mud, approximately 10 cm deep and covered in leaf litter, then topped with water of 15 cm depth. The eels initially burrowed into the mud, then slowly emerged to swim around the tank at intervals. Upon lowering the water level to about 5 cm, the specimens settled down and spent more time buried in the substrate. They would rise to the surface every 10–15 minutes to gulp air ( Fig. 8B & C View FIGURE 8 ). Chopped earthworms and chironomid larvae were readily accepted. The fish were observed at rest lying on their sides or upside down on the surface of the mud.

Local name and uses

Ophichthys hodgarti is known as ‘Yuveh’ in the Adi language, and infrequently used as a food source by the Adi community.

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