A total of 514 marine fish species from 71 families were recorded during the rapid biodiversity assessment at D’Arros Island and St. Joseph Atoll between the 5th and 24th of May 2017. Fifty one percent of the recorded species were represented by eight families: Labridae (66 species), Gobiidae (48 species), Pomacentridae (33 species), Serranidae (30 species), Acanthuridae (26 species), Chaetodontidae (20 species), Scaridae (20 species) and Carangidae (17 species). During the rapid assessment between the 5th and 24th of May 2017, 12 species previously unreported from Seychelles waters were recorded. An additional 4 new Seychelles species records were subsequently recorded during ad hoc surveys between July 1st and the 19th of November 2017. The 16 previously unreported species from Seychelles represented seven families including: Chaetodontidae, Congridae, Gobiidae, Labridae, Microdesmidae, Syngnathidae and Tetraodontidae. Ten of the new Seychelles species records (Amblygobius nocturnus, Arothron caeruleopunctatus, Dunckerocampus boylei, Gorgasia maculata, Gunnellichthys monostigma, Heniochus diphreutes, Oxycheilinus orientalis, Trimma anaima, Trimma emeryi and Vanderhorstia ambanoro) have relatively cosmopolitan regional distributions and were expected to occur in Seychelles (Figs. 2 and 3). This report serves to confirm their presence in Seychelles waters. The occurrence of the remaining six species (Iniistius naevus, Pseudocoris petila, Pseudojuloides labyrinthus, Trimmatom offucius, Trimma taylori and Trimma winchi) in Seychelles waters represent new range extensions within the Indian Ocean of between 2000 and 4300 km (Fig. 4). Each species was photographed and notes on their occurrence, characteristics and distribution were recorded.
Amblygobius nocturnus (Herre 1945) (Fig. 2a) was observed and photographed in the lagoon of St. Joseph Atoll (5°25′42.94″S 53°19′26.81″E) at a depth of 3 m on the 20th of May 2017. This species is characterised by a pale grey body with a brown to orange stripe running from the snout through the eye and a row of 8–9 dark spots at the base of the dorsal fin (Froese and Pauly 2001, Allen et al. 2003). Distribution ranges from the Red Sea to the Maldives and Mauritius (GBIF) to the Philippines and French Polynesia (Randall 1995; Anderson et al. 1998) and there has been one unpublished report from Seychelles Inner Islands.
Arothron caeruleopunctatus (Matsuura 1994) (Fig. 2b) was observed and photographed north of D’Arros Island (5°24′36.9″S 53°17′49.5″E) at a depth of 16 m on the 15th of May 2017. This species is characterised by alternating light and dark rings around the eye, and a black patch with white spots at the base of the pectoral fins (Allen and Erdman 2012). Distribution ranges from Réunion and the Maldives to Indonesia (Froese and Pauly 2001).
Dunckerocampus boylei (Kuiter 1998) (Fig. 2c) was observed and photographed on the west side of St. Joseph Atoll (5°24′46.59″S 53°18′59.21″E) at a depth of 18 m on the 22nd of May 2017. This species is characterised by broad red bands and caudal fin with distinct black posterior margin and upper and lower white margins (Kuiter 1998). Known from the Red Sea, South Africa, Mauritius and Indonesia (Allen and Erdman 2012; Kuiter 1998).
Gorgasia maculata (Klausewitz and Eibl-Eibesfeldt 1959) (Fig. 2d) was observed and photographed on the north side of D’Arros Island (5°24′32.55″S 53°17′58.20″E) at a depth of 26 m on the 17th of May 2017. This species is characterised by a tan body with the lateral line pores covered in white flecks with larger white blotches on the head (Allen et al. 2003). Distribution ranges from the Comoros Islands and Maldives in the West Indian Ocean to the Solomon Islands in the Pacific (Froese and Pauly 2001, Allen et al. 2003).
Gunnellichthys monostigma (Smith 1958) (Fig. 2e) was observed and photographed off the north side of D’Arros Island (5°24′32.55″S 53°17′58.20″E) at a depth of 26 m on the 19th of May 2017. This species is characterised by a pale grey body with a distinctive small black spot posteriorly on the opercula and a blue stripe on the head and behind eyes (Allen and Erdman 2012). Distribution ranges from the Red Sea and East Africa to Micronesia and Australia (Allen and Erdman 2012).
Heniochus diphreutes (Jordan 1903) (Fig. 2f) was observed and photographed off the south side of D’Arros Island (5°25′31.19″S 53°17′55.28″E) on the 6th of May 2017. This species is characterised by a pair of black bands across the body with the second band ending at the tip of the anal fin (Allen et al. 2003). This species lacks the distinct black rectangle between eyes and the longer snout of Heniochus acuminatus (Allen et al. 2003). Distribution ranges from the Red Sea and East Africa to Indonesia and Australia (Allen et al. 2003).
Oxycheilinus orientalis (Günther 1862) (Fig. 3a) was observed and photographed off the north side of D’Arros Island on the 12th of May 2017. Males of this species (pictured) are characterised by a mid-lateral red stripe with a pair of spots on the tail (Allen and Erdman 2012). Distribution ranges from the Red Sea and East Africa to Indonesia (Froese and Pauly 2001).
Trimma anaima (Winterbottom 2000) (Fig. 3b) was observed and photographed off the west side of St. Joseph Atoll (5°24′46.59″S 53°18′59.21″E) at a depth of 18 m on the 23rd of May 2017. This species is characterised by a broad red or orange mid lateral stripe, white belly and thin blue lines below eyes (Allen and Erdman 2012). Distribution ranges from the Comoro Islands and Maldives Islands to Indonesia (Allen and Erdman 2012).
Trimma emeryi (Winterbottom 1985) (Fig. 3c) was observed and photographed on the east side of D’Arros Island at a depth of 20 m on the 8th of October 2017. Characterised by red iris and a yellow to pink head and a translucent pale yellow body (Allen and Erdman 2012). Distribution ranges from the Comoro Islands and Maldives to Chagos and Indonesia, Guam and Tonga (Allen and Erdman 2012).
Vanderhorstia ambanoro (Fourmanoir 1957) (Fig. 3d) was observed and photographed in the lagoon of St. Joseph Atoll (5°25′42″S 53°19′26″E) on the 20th of May 2017. This species is characterised by a pale grey to white body with large black spots laterally and smaller dorsal spots and blue streaks on head and dorsal surface (Allen and Erdman 2012). Distribution ranges from the Red Sea, Madagascar and East Africa to Micronesia and Samoa (Allen and Erdman 2012).
Iniistius naevus (Allen and Erdman 2012) (Fig. 4a) was observed and photographed off the north side of D’Arros Island (5°24′33.16″S 53°17′57.77″E) at a depth of 24 m on the 18th of May 2017. This species is characterised by a white belly patch with a dark red blotch above it and a similar size yellow blotch anterior to it (Allen and Erdman 2012). Previously only known from the Andaman Islands (Allen and Erdman 2012). This record extends the known range by approximately 4300 km and confirms its occurrence in the West Indian Ocean.
Pseudocoris petila (Allen and Erdman 2012) (Fig. 4b) was observed and photographed off the western side of St. Joseph Atoll (5°24′46.59″S 53°18′59.21″E) at a depth of 12 m on the 22nd of May 2017. This species is characterised by a distinctive purple cheek and elongate body. Previously only known from the Andaman Islands (Froese and Pauly 2001, GBIF), 4300 km to the east. However, there have been more recent unconfirmed reports from South Africa, Réunion Island and Pulau Weh (Allen and Erdman 2012).
Pseudojuloides labyrinthus (Victor and Edward 2016) (Fig. 4c) was observed and photographed on the northern side of D’Arros Island (5°24′33.16″S 53°17′57.77″E) at a depth of 26 m on the 19th of November 2017. The terminal male (photographed) is characterised by a maze of blue lines on the head and three blue stripes along the body. Only previously known from the aquarium trade in Kenya approximately 2000 km west of Seychelles (Victor and Edward 2016).
Trimmatom offucius (Winterbottom and Emery 1981) (Fig. 4d) was observed and photographed off the west side of St. Joseph Atoll (5°24′46.59″S 53°18′59.21″E) at a depth of 18 m on the 15th of September 2017, after the rapid biodiversity assessment was completed. This species is characterised by an orange-red bar about the diameter of the eye across the cheek below the eye (Winterbottom and Emery 1981). Known previously from Chagos Archipelago (Winterbottom and Emery 1981). This record extends its known range by approximately 2000 km further westward and confirms its occurrence in the Southwest Indian Ocean.
Trimma taylori (Lobel 1979) (Fig. 4e) was observed and photographed off the west side of St. Joseph Atoll (5°24′46.59″S 53°18′59.21″E) at a depth of 18 m on the 23rd of May 2017. Subsequent photographs of the specimen shown here were taken at the same location on the 16th of September 2017. This species is characterised by elongate second dorsal spine, semi-translucent upper body and yellow to orange spots on the head and median fins (Allen and Erdman 2012; Froese and Pauly 2001; Winterbottom 1984). Distribution ranges throughout the East Indies and is also known from the Red Sea and Chagos Archipelago in the central Indian Ocean (Allen and Erdman 2012; Froese and Pauly 2001). This record extends the known range by approximately 2000 km west of Chagos and confirms its occurrence in the Southwest Indian Ocean.
Trimma winchi (Winterbottom 1984) (Fig. 4f) was observed and photographed off the west side of St. Joseph Atoll (5°24′46.59″S 53°18′59.21″E) at a depth of 18 m on the 23rd of May 2017. Subsequent photographs of the specimen shown here were taken at the same location on the 16th of September 2017. This species is characterised by a yellow body, pink jaws, black melanophores along mid-lateral line and elongated second dorsal spine reaching posteriorly slightly beyond the base of the last dorsal fin ray (Winterbottom 1984). Known previously from Chagos Archipelago (Winterbottom 1984; Froese and Pauly 2001). This record extends the known range of the species by approximately 2000 km further westward and confirms its occurrence in the Southwest Indian Ocean.