Chtenopteryx sicula

A Ctenopteryx ...

• with ocular but without (?) visceral photophores.
• with arm suckers in at least 4 series distally.
• with club suckers in more than 8 series.

1.  Arms
   • Formula: 4>3>2>1.
   • Arms I-III with 2 sucker series proximally becoming at least 4 series distally.
   • Arms IV with 1-2 zigzag series of suckers.
2. Tentacles
   • Club without keel or protective membranes (Naef's large specimen was damaged, this character has questionable validity).
   • Suckers of club in more than 8 series.
3. Photophores
   • Large photophore present on ventral surface of eye.
   • Visceral photophore absent (see illustration below), or present*.
     
     
     
     Figure. Ventral view of the viscera of C. sicula, apparently the same specimen as in the title illustration, showing the absence of a visceral photophore and the presence of the accessory nidamental gland. Drawing modified from Naef, 1921/23b.
4. Buccal membrane
   • Each buccal support with 2 series of suckers.
5. Occipital folds
   • Three folds present with olfactory organ on first.
6. Fins
   • Do not quite reach anterior margin of mantle.
7. Gladius
   • Flat, spoon-like conus present.

Comments: 

A detailed description of this squid from the Mediterranean has not been published to our knowledge. The description of Pfeffer (1912) was based on squid of 13 mm ML and smaller. Joubin (1900) described a composite of three squid of about 50 mm ML taken from the stomach of a dolphin caught off Corsica. Unfortunately these specimens were in poor condition. Earlier descriptions lacked detail. Naef, 1921-23a, made the most detailed description of this species from squid captured off Naples. The description presented here is based on his account.

*We have examined a specimen of C. sicula from the Mediterranean Sea that has the visceral photophore. There may be two species in the Mediterranean going by the name C. sicula; if so, we don't know which is the true C. sicula.

The paralarval stages are similar to those of other species of Chtenopteryx. Chromatophore differences, if present, have not been identified as yet.

Figure. Left - Two very young paralarvae, ca. ...mm ML, side view. The circular tentacular clubs have about 20 suckers, irregularly arranged. Two chromatophores are present on each side of the mantle. Middle - A more advanced paralarva, ca ... mm ML, ventral, dorsal and side views. An equatorial circulet of 7 large yellow-brown chromatophores is present on the mantle. Posteriorly the expanded vanes of the gladius are visible in the dorsal view. Right - A even more advanced paralarva, ca. ... mm ML, ventral and dorsal views. Drawings and description of paralarvae paraphrased from Naef, 1921/23a.

Chtenopteryx fimbriatus Appellof, 1890, (from off Messina, Mediterranean Sea) Chtenopteryx cyprinoides Joubin, 1894 (from Corsican waters, Messina, Mediterranean Sea stomach of a dolphin) and Chtenopteryx neuroptera Jatta, 1896 (from off Napels, Mediterranean Sea) are considered synonyms of C. sicula by Pfeffer (1912). We accept this view until it can be established that more than one species of the genus is present in the Mediterranean Sea. Pfeffer (1912) established a new form (Chtenopteryx sicula forma chuni) based on a 7 mm ML squid described by Chun from the Indian Ocean. The distinction was based on developmental differences in fin length compared to Mediterranean specimens at similar sizes.

There is some confusion in the literature over the proper spelling of the species name. The species was originally named as Sepioteuthis sicula but the ending was emended by Pfeffer (1912) to siculus when he placed the species in Chtenopteryx. Mike Sweeney checked into this and replies, "...I just had a conversation with Ted Bayer. Verany used sicula as an adjective for the Sepioteuthis of Sicily. Chtenopteryx is feminine and therefore requires the species ending as sicula (not siculus)."