Rossiinae Appellof, 1898

Introduction

Members of the Rossinae are among the larger sepiolids reaching up to 10 cm ML (Reid, 1991). They are benthic and mostly occupy the outer portions of the continental shelves and upper regions of the slope. The subfamily nearly has a world wide distribution (see below) along parts of major land masses but is not know from Antarctic waters.

Brief diagnosis:

A sepiolid ...

• with dorsal mantle free from head.
• without ventral mantle shield.

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Figure.  Left - Anterodorsal view of a Rossinae sitting on the ocean floor at 1100 m. Note the dorsal separation between head and mantle. Right - Side view of a swimming Rossinae at 1033 m, showing the ventral surface of the mantle which lacks any trace of a ventral shield. Note that the tentacle is coiled inward and not retracted into a pocket as in sepiids.

Characteristics

1. Arms
1. Interbrachial web weakly developed between arms I-III.
2. Non-hectocotylized arm suckers in 2 series in most species but 4 series in at least two species.
3. One or both dorsal arms of male hectocotylized; often with suckers in two or four series among other modifications.
   
   
2. Tentacles
1. Tentacular clubs usually expanded.
2. Keel along full length of club.
   

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   Figure. Oral view of the tentacular club of Rossia pacifica, preserved. Photograph by R. Young.

3. Mantle
1. Mantle free from head in nuchal region; nuchal cartilage present.
   

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   Figure. Dorsal view of the mantle and head of Rossia macrosoma with anterior portion of mantle folded back to reveal the nuchal cartilage (blue) and anterior end of the gladius (red). Drawing modified from Naef (1921-23).

4. Gladius
1. Gladius fully-developed but thin posteriorly.
   
   
5. Viscera
1. Bursa copulatrix absent.
   
   
6. Photophores
1. Photohores, when present, with with small, separate oval lenses.

Comments

The following table compares the four genera.

Austrorossia is often considered a subgenus of Rossia (Voss, 1956; Reid, 1991). We follow the classification of Nesis (1982/87).

Life History

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Figure. Rossinae egg cluster from the same area in the Gulf of Mexico. Left - A recently laid cluster at a depth of 540m attached to the sponge, Topsentia sp. The individual capsules are approximately 1 cm in width.  Middle - An older cluster, at a depth of 550 m, with embryos close to hatching (note the eyes within the capsules), attached to an octocoral. Right - A small Rossinae, ca. 2 cm in length, photographed about the same time and place as the egg capsules and probably of the same species.

Distribution

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Figure. Distribution map of the Rossiinae (white lines). Distributions are approximate. Modified from Young, et al. (1998).

References

Reid, A. 1991. Taxonomic Review of the Australian Rossiinae (Cephalopoda: Sepiolidae), with a Description of a New Species, Neorossia leptodons, and Redescription of N. caroli (Joubin, 1902) . Bulletin of Marine Science, 49(3)(1991):748-831.

Young, R. E., M. Vecchione and D. Donovan. 1998. The evolution of coleoid cephalopods and their present biodiversity and ecology. South African Jour. Mar. Sci., 20: 393-420.

Voss, G.L. 1956. A Review of the Cephalopods of the Gulf of Mexico. Bulletin of Marine Science of the Gulf and Caribbean, 6(2):85-178.