Alpheus of palm bearing shallow transverse groove proximal

 

 

Alpheus
bisincisus De Haan, 1849 in De Haan,
1833-1850 

Synonyms : Alpheus bisincisus De Haan, 1849 in De Haan, 1833-1850,  Alpheus bisincisus malensis Coutière, 1905, Alpheus bis-incisus var. malensis Coutière, 1905, Alpheus bis-incisus var. stylirostris Coutière, 1905, Alpheus bisincisus var. variabilis de Man, 1909.

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Distribution : Japan, Ceylon, Indonesia and South Africa, Indian
ocean

Environment
: Marine,
upto depth of 20 m

Size
:  15 mm

Collecttion
site : Sakthikulangara

Species
examined : 1 
male specimen examined of size 7 cm

Description : Rostrum reaching almost to end of first antennular
article; varying from 1.8-3.0 times as long as broad at base. Rostrum flattened
dorsally with margins overhanging deep orbitorostral grooves and disappearing
well posterior to eyes. Orbitorostral margin varying from slightly to abruptly
concave. Visible part of first antennular article a little longer than third
article, second article 1.5 times longer than visible part of first antennular
article and 2.0 times as long as wide. Stylocerite reaching to end of first
antennular article. Scaphocerite with outer margin concave, lateral tooth extending
well beyond narrow squamous portion and as long as antennular peduncle. Carpocerite
as long as antennular peduncle. Large chela 2.4 times as long as broad, fingers
occupying distal 0.4. Palm broader than fingers.

 

 Plunger of dactylus of strong development.
Proximal shoulder subacute, markedly overhanging superior saddle; distal
shoulder gradually rounded. Lateral palmar depression shallow and quadrangular,
extending to linea impressa. Medial palmar depression triangular, apex
disappearing in the proximal third of chela. Inferior notch well marked;
infE;rior shoulder strong, subacute, continuing 0.3 the distance up lateral
face, with margin well defined. Near inferior margin of medial face is a narrow
longitudinal groove that extends from inferior notch to proximal half of palm.
Merus 1.6 times as long as broad, bearing long

 

 

 

 

 

 hairs and a
strong tooth distally on inferointernal margin. Small chela sexually dimorphic
with that of male balaeniceps varying from 2.3 to 4.0 times as long as broad,
fingers and palm almost equal in length. Superior margin of palm bearing
shallow transverse groove proximal to dactylus. Fringes of setae on dactylus meeting
on superior su rface at distal third. Pollex bearing a fringe of short hai rs
extending from near point of articulation to middle. Merus 2.4 times as long as
broad, bearing an acute tooth distally on inferointernal margin. Female chela
not balaeniceps, 4.5 times as long as broad, fingers a little longer than palm.
Merus 3.3 times as long as broad with tooth similar to that of males. Carpal
articles of second legs with ratio of: 10:7:2:2:3. Third leg with spine on
ischium. Merus inermous, 5 times as long as broad. Carpus 0.5 as long as merus,
superodistal margin projected as a small rounded tooth; inferodistal margin
bearing a slender acute spine. Propodus 0.8 as long as merus bearing 7 spines
with a pair distally on inferior margin. Dactylus simple, 0.4 as long as
propodus. First four abdominal sterna of male bearing small flat processes
extending posteriorly. Telson 2 times as long as broad at posterior margin.
Posterior margin slightly arcuate; dorsal spines large (Banner and Banner 1982)

 

Remarks : There are doubts regarding the distributional records of
the particular group from different places as one of the species confirned as A. bisincisus was later found as Alpheus  audouini.

 

Original description : De Haan, W. (1833-1850). Crustacea. In: von Siebold,
P.F., Fauna Japonica sive Descriptio Animalium, quae in Itinere per Japoniam,
Jussu et Auspiciis Superiorum, qui Summum in India Batava Imperium Tenent,
Suspecto, Annis 1823-1830 Collegit, Notis, Observationibus et Adumbrationibus
Illustravit. i-xxxi, ix-xvi, 1-243, Plates A-J, L-Q, 1-55.
Lugduni-Batavorum.