Apterichtus caecus ( Linnaeus 1758 )

Hibino, Yusuke, 2015, A review of the finless snake eels of the genus Apterichtus (Anguilliformes: Ophichthidae), with the description of five new species, Zootaxa 3941 (1), pp. 49-78 : 56-57

Apterichtus caecus ( Linnaeus 1758)

Figure 3 , Table 1

Muraena caeca Linnaeus (ex Brander) 1758:245 (type locality Mediterranean Sea [original: "in Mari Mediterraneo"]. Type unknown or lost; based on a description in manuscript by E. Brander. Neotype MNHN-IC-0000-2125, described herein, from Iviça, a Balearic Isle off Spain in the Mediterranean.

Apterichtus caecus ( Linnaeus 1758) : Blache & Bauchot 1972:711.

Caecula apterygia Vahl 1794:156 , an unneeded substitute name for Muraena caeca Linnaeus 1758 .

Caecilia branderiana Lacepède 1800:134 , an unneeded substitute name for Muraena caeca Linnaeus 1758 .

Apterichtus caecus: Delaroche 1809:325 .

Diagnosis. An elongate species with: tail 1.6–1.7, head 12–15, and body depth 56–83 in total length; 4 preopercular pores and 5 pores in supratemporal canal; teeth conical, uniserial on jaws, becoming biserial on vomer of large specimens; 8–14 vomerine teeth; body coloration (when fresh) ochre with numerous small dark brown spots, those spots forming a continuous mid-dorsal band, yellowish on ventral surface, head with dark brown spots over a pale background, a prominent horizontal white patch beneath and behind the orbit ( Fig. 3 ); and MVF 52–134, total vertebrae 132–139 (n=6).

Size. The largest known specimen is 60 cm.

Distribution. Known from 0–85 m depth, usually in fine sand. Western and eastern Mediterranean, eastern Atlantic south to Azores, Madeira, and the Canary islands.

Remarks. Muraena caeca was described by Linnaeus (1758) from the Mediterranean in a terse 42 word unillustrated description. Subsequent authors agree that the type specimen is lost. The next mention of M. caeca was that of Duméril (1806) who created the generic name Apterichtus for caeca . The first comprehensive treatment of the species was that of Delaroche (1809) in which he well-described and illustrated a specimen from Iviça, a Balearic Island in the Mediterranean off Spain. He considered Linnaeus’s description to be “très-exacte, mais trèsincomplete” and on the basis of his “28 ½ centimeter” specimen provided an extensive description and illustration. The specimen now resides in the Muséum National d'Histoire Naturelle (Paris) and was redescribed and illustrated by Blache and Bauchot (1972:711–714) along with another specimen from eastern Africa. Blache and Bauchot (p. 711) erroneously stated that the specimen (“n o MNHN, Paris: 2125”) collected by Delaroche from the Baléares was 497 mm TL. Their other specimen (“n o MNHN, Paris: 1884–426”) was said to be 284 mm TL and to have been collected by Vaillant off east Africa. Because of the disagreement with the length so precisely cited by Delaroche we presume that Blache and Bauchot erroneously reversed the collection data and sizes of the two specimens, and we presume that the 284 mm specimen is that of Delaroche. We have examined the Delaroche specimen and find it to be an adequate, albeit slightly twisted, specimen. It has 137 total vertebrae (52 preanal) and the following measurements (in mm): total length 284; head length 21.3; trunk length 94.7; jaw length ca. 8.4 (the jaw is cut at the rictus on both sides); snout length 3.6; eye diameter 1.0; interorbital width 1.3; body depth at gill opening ca. 5.4; and body width at gill opening ca. 4.6. Its dentition was illustrated by Blache and Bauchot ( Figure 7 , p. 713). It has the following cephalic pores: single median interorbital and temporal pores; supraorbital pores 1+4, infraorbital pores 5+2, supratemporal pores 5, lower jaw pores 5, preopercular pores 4; lateral-line pores difficult to count accurately due to small size and waxy exudate, 8 in branchial region.

Our description of Apterichtus caecus is primarily based on Pereira and Aguiar’s (1979) description of five Azorean specimens, as well as Blache and Bauchot’s (1972) description and illustrations, and McCosker’s examination of the neotype and a specimen from Italy. Blache and Bauchot’s second specimen (497 mm) has broadly separated biserial vomerine teeth. It agrees in other body proportions, pores and vertebrae (135). Wirtz et al. (2008: Figure 3 ) published a color photograph of an A. caecus taken at night in 14 m from Madeira. They also published a color photograph ( Figure 2 ) taken in 20 m from Madeira of what appears to be A. caecus ; it well demonstrates the ochre cephalic coloration of that species.

Blache and Bauchot (1972) and Leiby (1990) remarked that A. anguiformis and A. caecus have been confused with each other during the last two centuries and that most earlier references to adults and larvae are not clearly attributable to either species. In that no types existed for Linnaeus’ Muraena caeca, Blache and Bauchot (1972:709–710) analyzed its meager description and concluded that caeca most probably was based on the Mediterranean species of Apterichtus which has 135–138 vertebrae … and a preanal distance of 40.5–42.3% of the total length, rather than the species with the higher vertebral count (150–157), A. anguiformis . We agree with their conclusion and feel that it is appropriate to designate a neotype for Apterichtus caecus ( Linnaeus 1758) in our revision. We herein do so and designate MNHN-IC-0000-2125 to be the neotype.

Material examined. 2 specimens, 284–504 mm TL, including the neotype (MNHN-IC-0000- 2125, 284 mm), from Iviça, a Balearic Island in the Mediterranean off Spain. From Italy: Strait of Messina, MCZ 40861, 504 mm.

Figures

FIGURE 2. Underwater photograph of living Apterichtus flavicaudus, taken by J. Randall at 15 m, Makua, O’ahu, Hawai’i.

FIGURE 3. Underwater photograph of living Apterichtus caecus, taken by P. Gomes at night at 14 m, Funchal, Madeira.

FIGURE 7. Dentition of holotype of Apterichtus dunalailai, MNHN 1987 - 0810, 289 mm. Drawn by Corlis Schneider.