Trachinus pellegrini Cadenat, 1937

González, José A., González-Jiménez, José F., Triay-Portella, Raül, Jiménez, Sebastián, González-Lorenzo, Gustavo & Biscoito, Manuel, 2016, On the presence of Trachinus pellegrini (Trachinidae) in the Canary and Cape Verde Islands (north-eastern Atlantic), Cybium 40 (2), pp. 173-177 : 174-177

Trachinus pellegrini Cadenat, 1937 ( Figs 2A, B )

Material examined. - Canary Islands: MMF44358 , one subadult, 93.6 mm TL, 79.7 mm SL, 28°16.7’N 14°46’W, Banco de Amanay, South-west of Fuerteventura Island , 114 m of depth, cruise Infueco-0710, sta. BV2, soft substrate, 6 Jul. 2010, smallscale bottom trawl ; TFMC-VP/1946 , one subadult, 113.1 mm TL, 95.0 mm SL, 28°03’N 14°39’W, El Banquete, South of Fuerteventura Island , 188 m of depth, cruise Infueco-0710, sta. DR6, rocky bottom with sand, 10 Jul. 2010, dredge ; TFMC-VP/1947 ( Fig. 2A ), one juvenile, 68.0 mm TL, 59.6 mm SL, 28°15’N 14°48.5’W, Banco de Amanay, South-west of Fuerteventura Island, 141 m of depth, cruise Infueco-0611, sta. BV4, soft substrate, 11 Jun. 2011, small-scale bottom trawl. Cape Verde Islands : MMF42285 ( Fig. 2B ), one subadult, 119 mm TL, 101 mm SL, 15°55’N 22°56’W, Ponta Lacacão, Boa Vista Island, 122-137 m of depth, cruise Camarão-2, sta. 15, rocky bottom with sand, 7 Mar. 2012, bottom fish trap .

Selected body proportions and meristics of the specimens studied are shown in table I and compared with the scarce morphology data available from the literature ( Cadenat, 1937, 1938).

Regarding body proportions, data from the specimens examined herein agree in all respects with published data ( Tab. I ). Our specimens extend, above or below, the proportions IOD in %EDh, TL/Bdepth, TL/HL, EDh/SnL, PsOL/SnL and HL/EDh. In our specimens, pectoral fin length ( PL) seems to show a tendency to decrease with size. The opposite seems to occur with least depth of caudal peduncle (CPHt) and also with caudal peduncle length ( CPL) (taken at ventral profile). Also, inter-orbital distance ( IOD) seems to increase with size ( Tab. I ).

When comparing with the holotype, meristics of the specimens examined herein agree in almost all respects, except for some minor differences ( Tab. I ), e.g. in second dorsal fin rays (one ray less), anal fin rays (one more ray), pectoral fin rays (14-16 vs 17) and caudal fin rays (two more rays). Our adult and subadult specimens bear six spines in the first-dorsal fin, except for the juvenile individual, which has only five spines. Lower gill rakers on the 1 st arch coincide with the holotype. There is no published information on upper gill rakers to compare with our data. Lateral line scales ranged from 74 to 82 in our specimens, thus establishing a range that was not previously known. Antero-supraorbital spines in our material ranged from two to three, with one juvenile specimen bearing two on the right side and three on the left. Adult and subadult specimens examined have no preopercular spines. The juvenile has four small spines on the lower edge of preopercle ( Tab. I ).

Anal-fin rays are fleshy and their segmentation is hardly visible in adult or subadult specimens (ranging 94-119 mm TL), while they are not fleshy and segmentation is well visible in the juvenile specimen examined (68 mm TL).

Like in Roux (1981), our four specimens have the first dorsal-fin bluish grey. On the comparative table in Cadenat (1938), the author says the first dorsal fin is entirely transparent. However, in the text describing the species, Cadenat (1937, 1938) clarified that first dorsal-fin of type material is light bluish grey, bordered excessively pale yellow and with no trace of black spots, as found in other species.

Regarding the extraordinary development of the second-dorsal rays, Cadenat (1938) says that it is a minor character, manifesting perhaps at the time of reproduction, or is only a secondary sexual character in males.

The maximum published length for the species is 200 mm TL, common length 150 mm TL ( Roux, 1990). Our material ranges from 68 to 119 mm TL, most probably corresponding to juvenile to subadult individuals.

Remarks. - T. pellegrini is an eastern Atlantic species, ranging from Mauritania ( Froese and Pauly, 2015, FishBase) and Senegal to Nigeria, including the Cape Verde Islands ( Roux, 1990). Previous records from the Canary Islands by Roux (1981, 1990) could not be confirmed. Its presence around the Cape Verde Islands was confirmed by Menezes et al. (2004).

This is a tropical demersal species, inhabiting rock and sand bottoms ( Roux, 1981), to a maximum depth of 188 m [previously 150 m ( Roux, 1981; Schneider, 1990)]. The specimens examined herein were collected on rocky bottom with sand and on soft substrata, at depths between 122 and 137 m (Cape Verdes) and from 114 to 188 m (Canaries). The upper limit of its vertical distribution remains unknown. According to Roux (1981) it feeds mainly on crustaceans.

Trachinus pellegrini is recorded for the first time from the Canary Islands waters fixing now the northernmost limit (28°16.7’N) of the species distribution. Although the species was known with certainty from the Senegalese coasts ( Roux, 1990), Roux (1981) had already pointed out “possibly ranging further north” and it has been recently found in Mauritania ( Froese and Pauly, 2015, FishBase). Moreover, T. pellegrini is, up to date, the only Trachinus species inhabiting both the Canary and Cape Verde Islands.

In the last thirty years, sea surface temperature in the area of the Canary Islands has shown and increasing trend ( Santos et al., 2012), with records over 24°C. In this scenario, the appearance of T. pellegrini in the Canary Islands waters would not be surprising, and its presence could be one more evidence of the changes in the distribution of species due to warming in the Atlantic. This phenomenon (‘tropicalization’) has been observed in the Canaries even for species with low dispersal ability ( Falcón et al., 2002; Brito et al., 2005).

Another hypothesis explaining the present record of T. pellegrini in the Canaries could be its misidentification with T. radiatus , since both species have radiating bony crests on top of head behind eyes. Possibly the species is also present in the Atlantic Moroccan and Saharan neighboring coasts and has passed unnoticed. If this is the case, we are in the presence of a eurythermal species, occurring both in tropical waters (Cape Verdes) and in temperate waters (Fuerteventura banks, Canaries).

Acknowledgements. – The authors are indebted to researchers and tech- nical personnel participating in cruises and projects, which supported this work. Thanks are also due to the masters and crews of the research vessels. Cruises Infueco-0710 and Infueco-0611 were conducted in the framework of project INDEMARES (Code n° 1103009000), funded by EC Life+. Cruise Camarão-2 was made in the framework of project MARPROF-CV (PCT MAC 2007-2013, MAC/3/C124) co-funded by EU ERDF.

Figures

Figure 2. - Trachinus pellegrini. A: Juvenile from the Canary Islands (TFMC-VP/1947, 68.0 mm TL, 59.6 mm SL); B: Subadult from the Cape Verde Islands (MMF42285, 119 mm TL, 101 mm SL). Scale bars = 25 mm.

Tables

Table I. - Selected counts, morphometrics and body proportions of Trachinus pellegrini.

	MMF42285 1 specimen 119 mm TL Cape Verde Islands Present study			TFMC/VP1946 1 specimen 113 mm TL Canary Islands Present study			MMF44358 1 specimen 94 mm TL Canary Islands Present study			TFMC/VP1947 1 specimen 68 mm TL Canary Islands Present study		Cadenat (1937, 1938) 2 spec., 137-140 mm TL Cape Verde Islands holotype, 215 mm TL Guinea-Conakry
	mm	in in %SL %HL		mm	in in %SL %HL		mm	in %SL	in %HL	mm	in in %SL %HL	in in %SL %HL
Morphometrics and body proportions
Standard length, SL	101.0	–	–	95.0	–	–	80.0	–	–	60.0	– –	– –
Pre-first dorsal length, PD1L	26.0	25.7	–	21.0	22.5	–	19.0	23.5	–	16.0	26.1 –	no data –
Pre-second dorsal length, PD2L	39.0	38.6	–	35.0	36.8	–	28.0	35.1	–	21.0	35.8 –	no data –
Preanal length, PAL	41.0	40.6	–	35.0	37.2	–	28.0	34.8	–	25.0	42.7 –	no data –
Pre-anus length, PAnL	39.0	38.6	–	33.0	34.4	–	27.0	33.7	–	25.0	41.6 –	no data –
Prepectoral length, PPL	32.0	31.7	–	26.0	26.9	–	21.0	26.4	–	18.0	30.2 –	no data –
Pectoral fin length, PL	18.0	17.8	–	18.0	19.3	–	16.0	20.3	–	15.0	25.9 –	no data –
Head length, HL	31.0	30.7	–	27.0	28.7	–	23.0	28.9	–	20.0	32.7 –	no data –
Head height at posterior border of orbit, HHt	19.0	18.8	–	15.0	16.1	–	12.0	15.4	–	11.0	19.0 –	no data –
Preopercular length, POpL	20.0	19.8	–	21.0	22.1	–	17.0	20.8	–	14.0	23.3 –	no data –
Maximum body depth, Bdepth (at anus level)	25.0	24.8	–	21.0	21.7	–	18.0	22.4	–	15.0	24.5 –	no data –
Least depth of caudal peduncle, CPHt	8.0	7.9	–	7.0	7.4	–	6.0	7.1	–	4.0	6.7 –	no data –
Caudal peduncle length, CPL (at ventral profile)	7.0	6.9	–	4.0	4.2	–	2.5	3.1	–	2.0	3.1 –	no data –
Snout length, SnL (until mid level of eye)	5.0	–	16.1	3.5	–	12.8	3.3	–	14.3	2.6	– 13.1	– no data
Eye diameter, EDh (horizontal)	8.5	–	27.4	6.5	–	23.7	6.2	–	26.8	5.7	– 29.4	– 26.7-28.6
Eye diameter, EDv (vertical)	7.0	–	22.6	5.0	–	18.4	5.3	–	23.0	5.0	– 25.6	– no data
Inter-orbital distance, IOD	2.5	–	8.1	2.0	–	7.3	1.3	–	5.5	1.0	– 5.0	– no data
Post-orbital length, PsOL	19.0	–	61.3	18.0	–	66.0	14.0	–	60.9	12.0	– 60.4	– no data
Upper jaw length, UpJL	14.0	–	45.2	13.0	–	48.3	11.0	–	46.0	9.0	– 47.2	– no data
Gape length, GL	11.0	–	35.5	11.0	–	40.6	9.0	–	38.2	7.0	– 37.8	– no data
Length of longest dorsal–fin ray (4th)	8.0	7.9	25.8	broken	13.1+	45.7+	14.8	18.6	64.5	6.8	11.4 34.9	no data no data
Length of longest anal–fin ray	8.0	7.9	25.8	6.7	7.0	24.5	5.3	6.6	22.9	5.5	9.2 28.2	no data no data
IOD in %EDh		29.4			30.9			20.6			17.1	25.0
TL/Bdepth		4.76			5.48			5.25			4.64	4.75-5.00
TL/HL		3.84			4.15			4.07			3.49	3.75- 4.05
EDh/SnL		0.59			0.54			0.53			0.45	0.50
PsOL/SnL		3.80			5.14			4.24			4.60	4.90
HL/EDh		3.65			4.21			3.73			3.40	3.50-3.75