Goatfishes are tropical marine fishes that belong to the family Mullidae. Goatfishes are recognized by their bright color with strips and the presence of two long unbranched barbells on the chin. In the last decade, the number of goatfish species has increased noticeably (20 new species) owing to the interest of researchers in coastal fish diversity. Five specimens of Upeneus margarethae were reported for the first time from the Bay of Bengal region. The species has expanded its distribution range to the Thondi and Chennai coast of the Bay of Bengal. Five Upeneus margarethae were collected using commercial trawlers from August 2019 to January 2020. This species is characterized by having VIII dorsal spines, 13-14 pectoral fin rays, Lateral line 28-29, Gill rakers 20-21; 4 bars on both upper and lower caudal-fin, which was partly visible, and orange lateral mid-body stripe passing from eye to base of the caudal-fin. The detailed morphometric and meristic characters with a fresh color pattern representing images for the first time from the Palk Strait, Southeast coast of India, agree with the holotype specimen and comparable records from other areas of the world.

Keywords: Bay of Bengal, geographical, goat fish, mesh size, trawlers

Goatfishes are tropical marine fishes belonging to the family of Mullidae, comprising six genera and 101 species.^1,2 Mullidae is ecologically and commercially important fishes. Its inhabitants of shallow habitats are strongly associated with the coral reefs.³ Goatfishes are recognized by their bright color with strips and the presence of two long unbranched barbells on the chin, which are the main key characters for the taxonomical identification of the Mullidae family. In the last decade, 20 new goatfish species have been described owing to the developing taxonomic works and researchers' interest in coastal fish diversity.^2,4–6 Upeneus is one of the most prominent genera of the Mullidae family, with 47 species. The size range is 72-280 mm standard lengths (S.L.)⁶  They are characterized by 7-8 dorsal fin spines, chin barbels, small-sized teeth on palatines, vomer, jaws in multiserial and villiform teeth on jaws, the adult specimen length of barbels 4-7 and length of the snout 7-11 times in S.L.¹

According to Uiblein and Heemstra,⁴ the complex of Upeneus species is divided into four groups viz., japonicus, tragula, moluccensis, and vittatus based on morphological and meristics (Body-color patterns and bars on the caudal fin) characters. The Vittatus group was split into two groups: the stenopsis group established by Uiblein and Causse,⁷ and the Suahelicus group.¹ Further, the tragula group was split into another margarethae group comprising six species, U. margarethae, U. randalli, U. mouthami, U. caudofaciatus, U.gubal and U. heterospinus.^1,8 Currently, out of 47 species from Upeneus, 42 are classified into six groups viz., margarethae, japonicus, tragula, moluccensis, suahelicus, stenopsis, and the remaining five species are considered ungrouped.^6,8

The newly reported species U. margarethae is commonly called Margaretha's Goatfish, which comes under the margarethae group. The type locality of U. margarethae is from off Beira, Mozambic, in the Western Indian Ocean, and additional distribution ranges with a detailed morphometric comparison with known specimens.⁴ However, for the first time, the present study documented the occurrence of U. margarethae from the Thondi coast, Southeast coast of India, with taxonomic characters compared with known specimens, and current distribution ranges extensions were discussed.

Using commercial trawlers, five specimens of U. margarethae were collected from Thondi and Chennai coasts from August 2021 - January 2022. The specimens were photographed, and fishes were brought to the laboratory. The morphometric dimensions were documented using a Vernier caliper to the nearest 0.1 mm. Meristic characters, including fin ray counts, lateral series scales, and gill raker, were performed and identified based on the original description and other key characters by Uiblein and Heemstra.⁴ For comparative study, morphometric dimensions were converted into percentages of standard length. The current sample location-based distribution map with topographic features is created to envisage the distribution along the Indian coast (Figure 1).

Figure 1 Global distribution of Upeneus margarethae, the red circle indicating previous known sites and the block circle indicating the present sampling location of (capture at ) the Bay of Bengal.

Taxonomic classification

Phylum  Chordata

Class      Actinoptergii

Order      Perciformes

Family   Mullidae Rafinesque, 1815

Genus     Upeneus Cuvier, 1829

Species   Upeneus margarethae (Figure 2)⁴

Figure 2 Upeneus margarethae (A and B) from the Southeast coast of India, Bay of Bengal.

Material examined

The total length of five specimens ranges from 120.52 to 158.30 mm. The total length of two specimens collected from the Chennai coast on 09th August 2021 are 120.52 and 128.60 mm, whereas the three samples collected from the Thondi coast on 13th January 2022 are 122.10, 155.12, and 158.30 mm. The specimens were compared with other known Upeneus margarethae.

Diagnosis

The body is slightly compressed and oblong, with two barbels below the chin. Dorsal fins VIII spine and nine rays; branched pectoral-fin rays 13-14; upper (4) and lower gill rakers 16-17(20-21); scales of the lateral-line 28-29 (Table 2); Standard length in % in (S.L.); I dorsal fin body depth 24.6-25.9; body depth at anal 21.50-22.80; depth of caudal peduncle 10.7-10.9; width of caudal peduncle 5.14-5.58; head length 28.50-29.64; orbit length 6.80-6.90; upper jaw length 10.17-10.39; barbel length17.84- 18.00; caudal peduncle length 27.60-27.90; anal-fin base 10.74-11.12; the height of II dorsal-fin 18.19-18.65; length of pelvic fin 21.82-22.47; length of pectoral fin 21.03-21.46; width of pectoral fin 4.95-5.21(Table 1).

Color

The body and head have irregular red markings with a white base, dorsal fin with two red horizontal stripes; barbells are pale white; irregular brown blotches are present beneath the lateral line of the body, ventral side of the head and belly is white; pectoral fins hyaline, pelvic fins dull white with brown scatted blotches between the rays; upper and lower caudal lobe with four red bars partly visible, the origin of orange stripe from eye to caudal-fin base of the body (Figure 2).

Distribution

The type locality of Mozambic in Western India, Madagascar, Persian Gulf, Red Sea, Australia Western Pacific, off Kerala, off  Sri Lanka, and the distribution range extension to Thondi and Chennai coast, Bay of Bengal (Figure 1).

Still, information on taxonomic status is lacking with perceptible diagnostic morphometric meristic characters of Mullidae at the species level. Especially the pectoral-fin rays, dorsal-fin spines, gill rakers, lateral line scale count, and body color patterns play a significant role in species differentiation of this family. Twenty new species were added in the last decade, possibly due to researchers' developing taxonomic efforts and interest in exploring coastal fish diversity ecosystems. Twenty four species belonging to only three genera [Mulloidichthys (1), Parupeneus (11), and Upeneus- 12)] of the Mullidae family are known from the Indian waters.^9,10 The genus Upeneus possessing teeth can be easily distinguished from the similar genera, Mulloidichthys and Parupeneus, having no teeth on the vomer and palatines.^9,11–12 The present specimens belonged to the genus Upeneus by the presence of teeth patterns, and morphometric and meristic characters were identified as Upeneus margarethae, which agreed well with those from North Australia and Holotype specimens and previous descriptions.⁴

Morphometric characters (in % S.L.) observed in the current specimens were matched with the holotype and North Australia specimens measurements, followed by Sri Lanka and Red Sea specimens.⁴ But, slight range deviation was observed in the characters like Inter-orbital length (INTORB), Orbit length (ORBITL), First pre-dorsal length (SD1)Inter dorsal distance (D1D2), Caudal-peduncle width (CPDW), Caudal-peduncle length (CPDL and Pre-anal length (SANL) due to the ecological impact that may influence the inter-specific changes within the species. However, the meristic characters were similar to all the known specimens from Holotype, North Australia, Sri Lanka, and Red sea specimens except for gill raker counts.⁴ In some cases, morphological variation among populations from close-by ecological characters may influence the existing morphological variation, which may reflect phenotypic plasticity.¹³

The lack of detailed taxonomy studies of goat fishes, especially the Upeneus genus from Indian waters, needs a detailed study. Further, molecular studies are required to resolve the complexity of identifying species and understand the status of Upeneus diversity. The present study brings new insight and inference for the researchers and conservation of the species from the Southeast Coast of India.

The authors (KK and SR) thank the Department of Zoology, and Management of Kongunadu Arts and Science College, Coimbatore for their support.

The authors declare there are no conflicts of interest.

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