Comprehensive Description

Read full entry

Description

"Description

 

Carapace more or less pentagonal, armed with numerous spinelets and spiniform granules. No substantial variation in spine size observable among the specimens examined.

 

Regions convex, prominence of regions similar. Gastric region bearing four small spines in a pattern describing a square. A transverse row of four spiniform granules between the anterior pair and the base of the rostrum. A small spiniform granule externally to each anterior spine. Numerous spiniform granules throughout the region. Cardiac region with four small spines in a square-shaped pattern, along with numerous spinelets or spiniform granules distributed over the region. Each branchial region with around 30 small spines, generally similar in size, although some may have turned into small, spiniform granules in large individuals. Intestinal region bearing a pair of small spines. A small spine on the terminal angle of the pterygostomian region. Most of the spines on the different regions rather similar in size.

 

Rostrum with a short, bifid, somewhat upwardly directed anterior projection extending slightly beyond the corneas without reaching the end of the antennal peduncle. A pair of dorsal spines on the base, and usually another, smaller pair (or granules in some specimens) near the orbits. Sometimes a single, small spine on the dorsal surface of the anterior projection and another between the two dorsal pairs. Basal spine well-developed and visible in dorsal view, without overreaching the tip of the antennal peduncle, except in very young individuals. External orbital spine well-developed, larger than the other spines on the carapace, and extending beyond the base of the last antennal segment. Anterolateral spine smaller than the external orbital spine. Hepatic spine similar to the anterolateral spine in size. One-three small spines between these two. From the cervical groove to the level of the gastro-cardiac groove, three spines similar in size to the hepatic spine, with one or two smaller spines interspersed. Posterior to these another 10-12 small spines similar to the more anterior spines in size.

 

Second abdominal segment bearing a pair of small spines medially and several more on the borders on both the median and lateral plates. Numerous non-spiniform granules on the lateral plates on the third to fifth segments. Calcareous, non-spiniform nodules medially.

 

Ocular peduncle with some granules on the dorsal surface.

 

Basal segment of antennal peduncle with a small spine on the antero-external angle. Second segment pith a terminal, outer spine.

 

Chelipeds with merus bearing several spines, more developed on the dorsal and terminal borders. Carpus armed with five-six spines dorsaly and several more scattered over the outer, ventral surface. Hand bearing two poorly defined rows of spines dorsally. Two rows of more or less spiniform granules on the outer surface, others on the ventral and inner surfaces. Movable finger with some granules dorsally on the base. Tufts of setae on both fingers.

 

Third pair of walking legs between 2.3 and 3 times carapace length. Coxa bearing some scattered granules. Basis-ischium with small spines on the posterior, terminal border. Merus equal to or slightly less than carapace length, almost twice carpus length, and between 3.4 and 4.5 times longer than high (the lower values are for females). A row of 12-13 small spines on the anterior border. Two ragged rows of seven-eight small spines each on the posterior margin, smaller than the spines on the anterior border. Numerous small spines spread over the dorsal surface. Carpus armed with an anterior row of six-seven small spines with several smaller spines interspersed or slightly to either side. Various spinules on the outer surface. Propodus somewhat loner than the merus, between four and five times longer than high, and around 1.5 times the dactylus. A row of 10-13 spines on the anterior border. As on the carpus, this row poorly defined, with numerous small spines to either side. Another row of 11-12 somewhat smaller spines on the posterior margin. Numerous spinules on the dorsal surface. Ventral surface of propodus bearing two more or less well-defined rows of small spines. Ventral surface practically smooth on merus and carpus. Dactylus with four-five spines on the base of the anterior margin, one-two spines on either side, three-four corneous spines along the anterior border, and seven-eight small, corneous spinelets on the posterior margin. Dactylus slightly curved, without setae.

 

 

Size

 

 

Carapace length is 84 mm, carapace width 85 mm in the holotype. The allotype is 75 mm long and 73 mm wide. In the rest of the paratypes, carapace length ranges from 52 to 100 mm. The remaining female is 63 mm long and 61 mm wide.

 

 

Distribution

 

 

South of the Falkland Islands (Malvinas) (54°02.07' S, 58°40.4' W), Strait of Magellan (Punta Arenas), on muddy bottoms between 50 and 119 m in depth.

 

Because of the resemblance of this species to Lithodes santolla (Molina), it is likely that some reports of L. santolla in fact refer to this new species. Nevertheless, further study is required in order to determine its exact range.

 

 

Remarks

 

 

Lithodes confundens n. sp. is closely related to L. santolla (Molina), from the southern coasts of South America, in the shape of the rostrum, which is quite distinct from the rest of the species in this genus. Several characters readily distinguish these two species:

 

 

—Spinulation of the carapace, chelipeds, and walking legs considerably different. Fewer spines on the dorsal carapace surface in L. santolla, but the spines all much larger than those on L. confundens. Each branchial region in L. santolla bearing some 15-20 spines, whereas in the new species there are about 30 small spines (Plates 9-12).

 

—Fewer but much larger spines on the articles of the walking legs and chelipeds in L. santolla. Articles covered with many small spinelets in L. confundens (Figures 23, 24).

 

 

The presence of two more or less proximate species, in the Southwest Atlantic raises the possibility that we are dealing with a variant or subspecies. However, no intermediate characters that would support such a possibility were observed in any of the specimens examined. For this reason, and in view of the fact that the most important specific character (number of spines on the carapace and walking legs) are constant in all the Lithodes species examined (see p. 49), they have been considered separate species. Clearly, additional research into the distribution ranges of both species could shed more light on the matter.

 

 

Etymology

 

 

The name confundens is derived from the Latin "confundo", referring to the resemblance between this species and L. santolla and the confusion that could therefore arise between the two."

 

 

(Macpherson, 1988)

Trusted

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

Belongs to 0 communities

This taxon hasn't been featured in any communities yet.

Learn more about Communities

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!