Diplecogaster tonstricula, Fricke & Wirtz & Brito, 2015

Fricke, Ronald, Wirtz, Peter & Brito, Alberto, 2015, Diplecogaster tonstricula, a new species of cleaning clingfish (Teleostei: Gobiesocidae) from the Canary Islands and Senegal, eastern Atlantic Ocean, with a review of the Diplecogaster-ctenocrypta species-group, Journal of Natural History 50, pp. 731-748 : 737-743

Diplecogaster tonstricula new species

Eastern Atlantic cleaner clingfish

( Figures 1 – 6 )

Diplecogaster ctenocrypta (non Briggs 1955): Brito et al. 2002: 281, figures 364 – 366 (Canary Islands: El Hierro, Tenerife, Fuerteventura, 10 – 38 m). Brito et al. 2007: 98. Wirtz 2010: 42 ( Senegal). Wirtz 2012: 78 (Ngor Island, Senegal).

Holotype. ZSM 40089, 21.3 mm SL, Eastern Atlantic Ocean, Senegal, Dakar, 1.3 km southsouth-west of La Pointe des Almades , 14°43.806 ʹ N, 17°32.046 ʹ W, 28 m depth, P. Wirtz, 20 – 24 October 2009.

Paratypes. CCML uncat ., 2 specimens, 18.7 – 22.9 mm SL, Eastern Atlantic Ocean, Canary Islands, Fuerteventura , Morro del Jable , c . 28°02 ʹ 42 ʹʹ N, 14°21 ʹ 12 ʹʹ W, 38 m depth, R / V Ventura . ZSM uncat. [ex. 40089], 5 specimens, 11.8 – 21.1 mm SL, Eastern Atlantic Ocean, Senegal, Dakar, 1.3 km south-south-west of La Pointe des Almades , 14° 43.806 ʹ N, 17°32.046 ʹ W, 28 m depth, P . Wirtz, 20 – 24 October 2009.

Diagnosis

A species of Diplecogaster with 9 dorsal-fin rays, 8 anal-fin rays, 24 – 25 pectoral-fin rays, and 14 – 15 principal caudal-fin rays; 13 – 16 rakers on third gill arch; pelvic disc without lateral papillae in region A; disc region B with 2 rows of weak papillae; principal caudal-fin rays 14 – 15; interorbital distance 4.1 – 4.6 in head length; distance between disc and anus 14 – 17% of SL; head and body with 10 – 13 narrow vertical brownish bars; cheek with a white ocellus surrounded by black, and with a small black spot in the middle.

Description

Dorsal-fin ix; anal-fin viii; pectoral-fin xxiv-xxv; caudal-fin xiv-xv. Gill rakers on 3rd arch 13 – 16, very small, pointed.

Teeth small, conical, slightly recurved, in patches towards the front of each jaw, narrowing to a line of single teeth laterally.

Head lateral line system with 3 pores in nasal canal, 3 pores in postorbital canal, and 2 pores in lacrymal canal ( Figure 3 ); no mandibular pores.

Head broad, depressed. Head length 36.2 – 36.6% SL (2.7 – 2.8 in SL). Maximum body depth 17.1 – 20.1% SL (4.8 – 5.8 in SL). Maximum head width 24.0 – 24.1% SL (4.2 in SL). Maximum (horizontal) orbit diameter 10.3 – 11.5% SL (3.2 – 3.5 in head length). Snout short, rounded ( Figure 1a ). Preorbital length 7.5 – 9.6% SL (3.8 – 4.9 in head length); snout slightly elongate in males. Interorbital distance 8.0 – 8.7% SL (4.1 – 4.6 in head length). Upper jaw length 11.8 – 14.4% SL (2.5 – 3.1 in head length). Anus situated closer to the anal-fin origin than to the disc; distance between disc and anus 14.4 – 16.8% SL, distance between anus and anal-fin origin 7.9 – 9.6% SL. Preanus length 58.3 – 59.8% SL (1.7 in SL). Caudal – peduncle length 5.7 – 9.0% SL (11.0 – 17.6 in SL). Caudal – peduncle depth 13.3 – 18.2% SL (5.5 – 7.5 in SL).

Predorsal-fin length 65.2 – 71.6% SL (1.40 – 1.53 in SL). Preanal-fin length 69.9 – 74.3% SL (1.3 – 1.4 in SL). Prepectoral-fin length 35.6 – 36.1% SL (2.8 in SL). Prepelvic-fin length 24.3 – 24.7% SL (4.1 in SL). Predisc length 21.1 – 27.5% SL (3.6 – 4.7 in SL). Disc length 19.2 – 21.4% SL (4.7 – 5.2 in SL). Disc membrane inserting at base of 19th-21st pectoral-fin ray. Disc with 3 rows of papillae in region A, 2 rows of weak papillae in region B, and 4 rows of weak papillae in region C ( Figure 2 ). No lateral papillae in disc region A. Caudal-fin length 20.1% SL (5.0 in SL).

Colour in life ( Figures 4 and 6 )

Ground colouration of head and body usually bright orange, with narrow whitish or yellowish vertical bars, the first in the interorbital region. Preorbital section of head light olive green, which whitish streaks. Eye light olive green, dorsal half with five brown bars; iris surrounded by bright yellow ring. Cheek with a white ocellus surrounded by black. Fins orange.

Colour of preserved material

Head and body yellowish white, with 10 – 13 narrow vertical brownish bars ( Figure 1 ). Nape with small white spots. Cheek with a white ocellus surrounded by black, and with a small black spot in the middle. Fins translucent.

Etymology

Tonstricula (Latin) means little female barber. The name refers to the cleaning behaviour of the new species.

Comparison

The Diplecogaster-ctenocrypta group, comprising the species D. ctenocrypta and D. tonstricula n. sp., is characterised by a high number of 9 rays in the dorsal fin and 8 in the anal fin (other species of the genus: 4 – 8 rays in the dorsal fin, 3 – 7 rays in the anal fin), and the position of the anus which is situated closer to the anal-fin origin than to the end of the disc (other species of the genus: situated in the middle between disc and anal-fin origin). Species of the group are further distinguished from D. bimaculata , D. euxinica and D. pectoralis in having 14 – 15 caudal-fin rays (18 – 21 in D. bimaculata , D. euxinica and D. pectoralis ), and lacking lateral papillae in disc region A (many lateral papillae present in D. bimaculata , D. euxinica and D. pectoralis ), and from D. megalops in 13 – 16 rakers on third gill arch (7 – 9 rakers in D. megalops ).

Diplecogaster tonstricula n. sp. differs from D. ctenocrypta by having the pelvic disc without lateral papillae in region A (lateral papillae present in D. ctenocrypta ), disc region B with 2 rows of papillae (5 rows in D. ctenocrypta ), lacking mandibular pores (one mandibula pore present in D. ctenocrypta ), principal caudal-fin rays 14 – 15 (16 rays in D. ctenocrypta ), the interorbital distance 4.1 – 4.6 in head length (5.4 in head length in D. ctenocrypta ), the distance between disc and anus 14 – 17% of SL (19% of SL in D. ctenocrypta ), and 13 – 16 rakers on third gill arch (18 in D. ctenocrypta ). The live colour pattern of D. ctenocrypta is unknown, but the holotype is pale, without traces of bands, while the head and body of Diplecogaster tonstricula n. sp. is covered with 10 – 13 bars.

The species of Diplecogaster may be distinguished with an identification key (see above). Counts and proportions of the species of the genus are compared in Table 1 .

Distribution and habitat

Eastern Atlantic Ocean: Canary Islands (El Hierro, Tenerife, Fuerteventura), Senegal (Dakar). Probably more widespread in the region. The species was collected and observed at 10 – 38 m depth, mainly on hard substrate. It was observed to act as a facultative cleaner of larger fishes ( Figure 5 , Senegal, cleaning a muraenid, Gymnothorax afer ; Brito et al. (2002, figures 364 – 366), Canary Islands, cleaning a muraenid and a serranid).

Remarks

The new species was classified in the genus Diplecogaster as it agrees with the generic characters given by Briggs (1955) as 3½ gills, the gill membranes attached to the isthmus, the disc double, the dorsal and anal fins with strong rays, normal, the subopercular region without a spine, 24 – 25 pectoral fin rays, the absence of incisors or welldeveloped canines, and 13 – 16 rakers on the third gill arch. It is a member of the Diplecogaster-ctenocrypta group (comprising D. ctenocrypta and D. tonstricula n. sp.), which is characterised within the genus by a high number of 9 rays in the dorsal fin and 8 rays in the anal fin, and the position of the anus which is situated closer to the anal-fin origin than to the end of the disc.

The species was first described and illustrated by Brito et al. (2002, p. 281, figures 364 – 366) from the Canary islands, but it was confused by authors with Diplecogaster ctenocrypta Briggs 1955 . A recent examination of the holotype of that deep-water species ( ZMUC P9037 ) provided evidence that this is a separate species .

Cleaning behaviour has previously been observed in other gobiesocid fishes. Patzner and Debelius (1984) photographed a specimen of Diplecogaster bimaculata cleaning a moray eel, Muraena helena . Hutchins (1991) described Cochleoceps bicolor from southern and south-western Australia, and C. orientalis from south-eastern Australia, as setting up cleaning stations to remove parasites of other teleosts. Weitzmann and Mercader (2012) reported an observation of Lepadogaster candolii in the north-western Mediterranean Sea which was cleaning a grouper, Epinephelus marginatus .

Figures

Figure 1. Diplecogaster tonstricula n. sp., ZSM 40089, holotype, 21.3 mm SL, Senegal. (A) Lateral view; (B) dorsal view. Bar 3 mm.

Figure 2. Diplecogaster tonstricula n. sp., CCML uncat., paratype, specimen 1, 22.9 mm SL. Pelvic disc. Bar 1 mm.

Figure 3. Diplecogaster tonstricula n. sp., CCML uncat., paratype, specimen 1, 22.9 mm SL. Head lateral line system. (A) Dorsal view of head; (B) ventral view of head. Bar 1 mm.

Figure 4. Diplecogaster tonstricula n. sp., Senegal, Ngor Island, 28 m depth. Photograph by P. Wirtz, October 2009.

Figure 5. Diplecogaster tonstricula n. sp. cleaning a moray eel, Gymnothorax afer, Senegal, Ngor Island. Photograph by P. Wirtz, October 2009.

Figure 6. Diplecogaster tonstricula n. sp., Canary Islands, Tenerife, Rogelio. Photograph by Joaquín Guitérrez, February 2015.