Doclea rissonii   Leach,  1815 (Crab)
Organism information awaits expert curation
Taxonomy
Kingdom:Animalia
Phylum:Arthropoda
Class: Malacostraca
Order:Decapoda
Family:Epialtidae

Description
No spinules on the upper orbital margin. In the male, spines or tubercles on the fourth thoracic somite. Rostrum long, reaching beyond the spines of the epistome on the anterolateral angle of the buccal frame. 6 or 7 median tubercles or spines, of which only one is an intestinal spine. Pterygostomial canal absent. First ambulatory legs up to 4 times as long as the carapace. The pile of hairs on the ambulatory legs up to 4 times as long as the carapace. The pile of hairs on the ambulatory legs reaches to the proximal part of the propodus. The first male pleopod is smooth, almost straight and the distal appendage is abruptly narrowed and angular in the middle; the tip is pointed.

The carapace is globular. The reason is incised in the middle for 1.5 mm at the utmost. Between in incision and the pair of submedian tubercles anterior of the median line the rostrum is clearly grooved. In adults the tips of rostrum seem to be slightly towards each other, because the outer edge of each tooth is slightly convex. These is a narrow incision between the orbital margin and the postorbital spine. The outer edge of the postorbital spine is convex. In its median line the carapace carries seven tubercles or spines, of which the fourth, sixth and the seventh are the most pronounced. The first four tubercles are place in the mesogastric region, the fifth in the urogastric, the sixth in the cardiac and the seventh, which is directed obliquely upward and posteriorly, is in the intestinal region. The sixth median tubercle is sometimes followed by a small convexity. In the posterior part of the frontal region, just the anterior median tubercle, pair of submedian tubercles is present, the two rows diverging posteriorly. The first of these tubercles lies at the same level as the second median tubercle. The last is largest and placed at a level somewhat posterior of the third median tubercle. The metagastric region shows a very small tubercle at either end of the anterior margin. The hepatic region carries a single tubercle. Either inner anterior part of the branchial region has eleven tubercles forming three rows of respectively 2, 5 and 4 tubercles. The first (the outer) of these rows curves torwards the penultimate anterolateral spine. The other two rows start in the anterior part of the branchial row lies in a direct line with the protogastric row. The anterolateral border of the carapace is armed with four tubercles or spines. The first and the fourth are slightly more prominent than the second and third. A small tubercle, up to half as long as the first anterolateral spine, is sometimes placed at the edge of the pterygostomial region. The posterior spine of the basal antennal segment is very small. There is no pterygostomial canal. In the adult male the chelae are swollen and almost three quarters as long as the carapace. In the female the chelae have less than half the carapace length. The ambulatory leg of the first pair is 2.5 to 4 times as long as the carapace. The ambulatory legs are long and slender and the dense pile extends from the base to the proximal part of the propodus.

The dactylus is often purple in color. In the male all abdominal segments are separate. The second abdominal segment has a small median spine, while the third segment has a rounded convexity near the lateral edges of the segment. In the female the abdominal segments are also separate. The second abdominal segment has a small median tubercle, while the third segment has a less median prominence. In the male two strong submedian spines are present on the fourth thoracic somite, just before the seventh abdominal segment when the abdomen is in the normal position against the thorax. The first pleopod of the male, when fully mature, is well chitinized and circular in transverse section. It is smooth, the basal half is straight; the distal half is much narrow than the basal part, it is also straight, but directed obliquely outward.

Doclea gracilipes was distinguished from Doclea rissonii by Stimpson (1907) by having the last anterolateral spines longer. De Man (1888) also distinguished his Doclea andersoni on the same character from Doclea rissonii and mentioned it having three anterolateral spines. The holotype specimen of Doclea rissonii does have four (not three) anterolateral spines. In Doclea the size of the tubercles and spines changes considerably with the maturity of age of animals; in juveniles the spines as a rule are relatively (and often absolutely) longer than in larger specimens. The differences in spine length as described for Doclea rissonii, Doclea gracilipes and Doclea andersoni, fit very well in this picture, and in themselves are not sufficient to assign these specimens to different taxa. Dai (1981) described a new species Doclea sinensis from China. The difference between Doclea sinensis and Doclea andersoni are the following: there are 4 to 5 protuberances in the median line of the carapace in Doclea sinensis, instead of 2 as in Doclea andersoni, the fourth thoracic somite of the male of Doclea sinensis shows an acute ventral spine, in Doclea andersoni this spine is reduced or absent. Depending on size and maturity the length of the legs and spines changes as already mentioned above.


Synonym (s)
Doclea rissonii Leach, 1815

Common Name (s)
Economic Importance and Threats

Ecology
Habitat:  Muddy

Biogeography


• Tamil Nadu, Gulf of Mannar INDIA
• Gujarat, Gulf of Kachchh INDIA
• Maharashtra INDIA
• Orissa INDIA
• Tamil Nadu INDIA

Literature Source(s)
  • Jeyabaskaran, R; Wafar, S and Wafar, M (2002) CD on Brachyuran Crabs of West Coast, India Available at - http://www.nio.org/Biology/brachyuran/index.html
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at - http://www.marinespecies.org
  • Roy, MKD and Nandi NC (2007) Brachyuran diversity in coastal ecosystems of Tamil Nadu Journal of Environment and Sociobiology Social Environmental and Biological Association, Kolkata, India 4(2) 169-192 Available at - NIO,Goa

Page last updated on:2011-09-30

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