ANNALES ■ Ser. hist. nat. ■ 27 ■ 2017 ■ 1
short scientific article	DOI 10.19233/ASHN.2017.20
received: 2017-09-26
OCCURRENCE OF SLOANE'S VIPERFISH CHAULIODUS SLOANI (OSTEICHTHYES: CHAULIODONTIDAE) FROM THE TUNISIAN COAST
(CENTRAL MEDITERRANEAN)
Mohamed Mourad BEN AMOR & Khadija OUNIFI-BEN AMOR
Institut National des Sciences et Technologies de la Mer, 2060 La Goulette, Tunisia
Christian CAPAPÉ
Laboratoire d'Ichtyologie, case 104, Université Montpellier 2, Sciences et Techniques du Languedoc 34095 Montpellier cedex 5, France
E-mail: capape@univ-montp2.fr
abstract
This paper reports the occurrence of Sloane's viperfish Chauliodus sloani Schneider, 1801, from the Tunisian coast. Two specimens were collected by shrimp trawl during a scientific survey carried out in the northern area of the country. The specimens were caught in deep waters, at a depth of 410 m. The lack of knowledge of this species in the Mediterranean is probably due to the fact that it occurs in deep sea areas and is of little commercial interest.
Key words: description, morphometric measurements, meristic counts, distribution, deep waters
ritrovamento di pesce vipera chauliodus sloani (osteichthyes: chauliodontidae) lungo la costa della tunisia (mediterraneo
centrale)
SINTESI
L'articob riporta il ritrovamento de! pesce vipera Chauliodus sloani Schneider, 1801, lungo la costa tunisina. Due esemplari sono stati catturati con una rete a strascico per gamberi durante una spedizione scientifica effettuata nella parte settentrionale del paese. Gli esemplari sono stati catturati a 410 m di profondità. La mancanza di dati inerenti questa specie nel mare Mediterraneo è probabilmente dovuta al fatto che vive in acque molto profonde e ha scarso interesse commerciale.
Parole chiave: descrizione, misure morfometriche, conteggi meristici, distribuzione, acque profonde
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Mohamed Mourad BEN AMOR et al.: OCCURRENCE OF SLOANE'S VIPERFISH CHAULIODUS SLOANI (OSTEICHTHYES: CHAULIODONTIDAE) FROM ..., 163-166
INTRODUCTION
According to Gibbs (1984), two species of the genus Chauliodus Schneider, 1801, occur in the FNAM area: the Dana viperfish, Chauliodus danae Regan and Trewavas, 1929, only known in the eastern Atlantic, and Sloane's viperfish Chauliodus sloani Schneider, 1801, widely distributed in the Pacific, Indian and Atlantic Oceans, but also found in the Mediterranean Sea.
C. sloani has been previously recorded in the western Mediterranean Basin, especially in the seas surrounding Italy (Tortonese, 1970) and the Adriatic Sea (Lipej & Dulcic, 2010). Further investigations have reported the occurrence of this species eastwards, in the Greek waters of the Aegean Sea (Papaconstantinou, 1988), southwest off Cyprus (Galil, 2004), and in the Turkish waters of the Levant Sea (Dalyan & Eryilmaz, 2008).
C. sloani was noted as very rare off the Algerian coast by Dieuzeide et al. in 1954, and no new record has been observed since (Hemida, pers. com., 2017). Bradai et al. (2004) reported the species occurrence off northern Tunisian coast, but no specimen was available for confirmation. The C. sloani specimens described herein were collected during a scientific expedition of the Hannibal vessel organized by the Institut des Sciences et Technologies de la Mer of Salammbô (Tunisia). The paper also provides comments about the species' distribution in the local area and in the Mediterranean Sea.
MATERIAL AND METHODS
The two specimens were collected on 12 July 2017, with a shrimp trawl, at a depth of 410 m, on soft bottom, at the locality 37°33'08'' N and 09°45'49'' E (Fig. 1), together with other teleost species, the elasmobranch small-spotted catshark Scyliorhinus canicula (Linnaeus, 1758) and the deep-water rose shrimp Parapenaeus
Fig. 1: Map of the Mediterranean Sea showing Tunisia (rectangle) and indicating the capture site (black star) of the two specimens of Chauliodus sloani in the northern region.
Sl. 1: Zemljevid Sredozemskega morja z Tunizijo (pra-vokotnik) in označbo lokalitete (črna zvezdica), kjer sta bila ujeta primerka Chauliodus sloani na severu države.
Fig. 2: Chauliodus sloani, northern Tunisian region. A. Specimen referenced INSTM Chau-slo 01. B. Specimen referenced INSTM Chau-slo 02, scale bar for both specimens = 35 mm.
Sl. 2: Chauliodus sloani, Severna Tunizija. A. Primerek s kataloško številko INSTM Chau-slo 01. B. Primerek s kataloško številko INSTM Chau-slo 02, merilo za oba primerka = 35 mm.
longirostris (Lucas, 1846). The fresh specimens were measured for total length (TL), standard length (SL) and all morphometric characters to the nearest millimetre, and weighed to the nearest gram, on board. They were delivered to the laboratory for morphometric measurements and counts of meristic characters, which are summarized in Table 1. Both specimens were fixed in 10 % buffered formaldehyde, preserved in 75% ethanol and deposited in the Ichthyological Collection of the Institut des Sciences et Technologies de la Mer of Salammbô (Tunisia), under the catalogue number INSTM Chau-slo 01 and INSTM Chau-slo 02, respectively, and finally described in the present paper (Fig. 2) following Bello et al.'s (2014) protocol.
RESULTS AND DISCUSSION
The specimens were identified based on the following combination of characters: body long and compressed, covered by hexagonal scales on sides, with two ventro-lateral rows of photophores; head short with a minuscule snout, jaws with long fangs, numerous large teeth on premaxilla and dentary, lower jaw longer than the upper, dorsal fin close to head, first spinous ray prolonged, its origin over the eighth photophore in lateral series, pre-dorsal length; length from snout to dorsal fin 23.8/23.9 % of standard length (SL), dorsal adipose fin present near tail, colour iridescent silver-blue. The description, colour, all measurements and counts are in total agreement with Tortonese (1970), Gibbs (1984) and Dalyan & Eryilmaz (2008). Therefore, these two findings constitute the first well-documented record of the species in Tunisian waters, and Chauliodus sloani can be added to the list of local ichthyofauna.
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C. sloani can be distinguished from its co-generic species C. danae by its predorsal fin closer to head 1728% (usually 21-24%) SL versus in C. danae, 24-33% (usually 26-28%) SL. The origin of dorsal fin in C. sloani is over the fourth to eighth photophore in lateral series, and over the ninth to eleventh photophore in lateral series in C. danae. Additionally, C. sloani reaches a larger size than C. danae, more than 300 mm SL versus about 150 mm SL (Gibbs, 1984). The size of both Tunisian specimens, 226 mm SL and 160 mm SL, respectively, strengthens our diagnosis and confirms the occurrence of C. sloani in local waters.
In the wake of the local ecological knowledge following Anadón et al. (2009), used to track the geo-
graphical distribution of rare species in their living areas (Azzurro et al., 2011), information was gathered through contacts with fishermen, SCUBA divers, and sea lovers, concomitantly with regular surveys of Tunisian fish markets. These investigations showed that Chauliodus sloani was poorly known in the region prior to this capture. This could be due to the fact that the species inhabits waters of more than 1000 m in depth, and deep bottoms are little exploited by commercial vessels or not at all. Also, the species is not appreciated by consumers and therefore of no economic interest. This means that only scientific research offers the possibility to capture such a species in Tunisia, which is probably the case throughout the Mediterranean Sea.
References	INSTM Chau-slo 01		INSTM Chau-slo 02	
Morphometric measurements	mm	%SL	mm	%SL
Total length (TL)	251	111.1	174	108.8
Standard length (SL)	226	100	160	100
Head length	30	13.3	24	15
Eye diameter	6	2.6	5	3.1
Preorbital length	10	4.4	7	4.4
Predorsal length	54	23.9	38	23.8
Preventral length	98	43.4	83	51.9
Preanal length	191	84.5	147	91.9
Prepectoral length	40	17.7	30	18.8
Dorsal fin base	13	5.8	11	6.9
Ventral fin base	7	3.1	6	3.8
Pectoral fin base	4	1.8	3	1.9
Anal fin base	18	8	16	10
Adipose fin base	16	7.1	12	7.5
Meristic counts				
Dorsal fin rays	6		6	
Anal fin rays	10		10	
Pectoral fin rays	12		12	
Pelvic fin rays	7		7	
Caudal fin rays	11		11	
Number of photophores	8		8	
Number of teeth in upper jaw	8		8	
Number of teeth in lower jaw	14		14	
Total body weight (g)	19.5		9.5	
Tab. 1: The morphometric measurements in mm and as percentages of standard length (SL %), meristic counts and weight recorded in the two specimens of Chauliodus sloani from the northern Tunisian region. Tab. 1: Morfometrične meritve v mm in kot delež glede na standardno dolžino telesa (SL %), meristično štetje in teža dveh primerkov vrste Chauliodus sloani iz severne Tunizije.
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Mohamed Mourad BEN AMOR et al.: OCCURRENCE OF SLOANE'S VIPERFISH CHAULIODUS SLOANI (OSTEICHTHYES: CHAULIODONTIDAE) FROM ..., 163-166
O POJAVLJANJU MORSKEGA GADA CHAULIODUS SLOANI (OSTEICHTHYES: CHAULIODONTIDAE) V TUNIZIJSKIH VODAH (OSREDNJE SREDOZEMSKO MORJE)
Mohamed Mourad BEN AMOR & Khadija OUNIFI-BEN AMOR
Institut National des Sciences et Technologies de la Mer, 2060 La Goulette, Tunisia
Christian CAPAPÉ
Laboratoire d'Ichtyologie, case 104, Université Montpellier 2, Sciences et Techniques du Languedoc 34095 Montpellier cedex 5, France
E-mail: capape@univ-montp2.fr
POVZETEK
Avtorji poročajo o pojavljanju morskega gada, Chauliodus sloani Schneider, 1801, iz tunizijskih voda. Na strokovnih vzorčenjih sta bila na globini 410 m pri lovu kozic ujeta dva primerka na severu države. Pomanjkanje podatkov o tej vrsti je najverjetneje posledica dejstva, da se pojavlja v globokomorskem okolju, poleg tega pa ima zanemarljiv komercialni interes.
Ključne besede: opis, morfometrične meritve, meristična štetja, razširjenost, globokomorsko okolje
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