86 
PACIFIC SCIENCE, VoL VII, January, 1953 
Alphem ohesomanus Boone, Vanderbilt Mar. 
Mus., Bui. 6: 135, 1935. [Part of distribution 
records, only.] 
DESCRIPTION: Rostrum slender, acute, 
reaching almost to end of first article of an- 
tennular peduncle, straight to depressed at 
tip; small groups of short bristles along lower 
margin. Rostral base broad, flattened, not 
carinate dorsally, separated from carapace by 
deep and narrow sulci on each side. Orbital 
hoods rounded laterally, extending anteriorly 
as acute teeth from inner portion of hood, 
0.3-0. 5 length of rostrum. 
Antennular peduncle slender, with second 
article variable but usually only slightly longer 
than visible portion of first or third. Stylocer- 
ite well developed, reaching past middle of 
second antennular article. Lateral spine on 
basicerite acute, equal to or exceeding length 
of stylocerite. Scaphocerite long, distally nar- 
row, with lateral spine only slightly longer 
than squamous portion and reaching slightly 
beyond antennular peduncle and tip of car- 
pocerite. 
Large chela usually less than 2.5 times as 
long as broad, compressed, with margins 
rounded, without grooves or crests. Dactylus 
elongate, not strongly arcuate, 0.5 length of 
palm, tip usually acute in males, rounded in 
females. Merus with both superior and in- 
ferior internal angles obtuse, although pro- 
jecting; inferior internal margin with about 
5 spines. 
Small chela almost as long as larger but 
more slender, 2.5-3 times as long as broad. 
Dactylus strongly curved at tip, crossing fixed 
finger when closed. Inner margin of cutting 
face of fixed finger with distinct lamellar ridge 
along entire length, series of short strong bris- 
tles along outer edge. Fingers about equal in 
length to palm. Merus with superior distal 
angle subacute, often with several movable 
spines on inferior internal edge. 
Carpal articles of second legs totaling 1.7 
times length of merus and broad in propor- 
tion to width; second article only 1.5 times as 
long as broad; articles with ratio 10 ; 8 : 6 : 
6 : 12 . 
Ischium of third legs inermous. Merus in- 
ermous, over 3 times as long as wide, widest 
at 0.7 of length then tapering sharply to tip. 
Carpus with inferior margin continued as 
small tooth. Propodus with 5 to 7 movable 
spines, each with broadened and flattened tip. 
Dactylus heavy, blunt, laterally compressed, 
with thick longitudinal ridge on anterior face 
continuing around tip as transparent flange, 
blunt tip carrying ''fingernail” of hard chitin, 
tip reinforced with another ridge of chitin in 
form of horse’s hoof. Inferior and lower pos- 
terior portion of face of dactylus proximal to 
"nail” of soft and flexible chitin (see Fig. 
28 ^, /■). 
Body in general large and strongly com- 
pressed. Large females in collection range to 
42 mm. in length. Usually orange-red on up- 
per surface, sometimes longitudinally striped 
with deeper red along dorsal surface of cara- 
pace and abdomen; mottled with spots of 
deeper red along superior and superolateral 
portions of both large and small chela. 
DISCUSSION: The usual variation was noted 
in this species; much of it has been remarked 
upon in the description. Additional variation 
was found in the proportions of the small 
chela; in the ratio of the lengths of the carpal 
articles of the second legs, especially in the 
fifth article which varied from noticeably 
shorter than the first to somewhat longer; and 
in the number of spines on the propodus of 
the third legs. The fingers of the large chela 
show sexual dimorphism, but a few specimens 
seemed to intergrade. One specimen in the 
collection had an orbital tooth on the right 
but not on the left side. 
These specimens agree well with the brief 
description given by Milne-Edwards. De Man 
( 1911 ) remarked on the variation manifested 
by the few specimens of this species in his col- 
lection and noted that the second article of 
the antennular peduncle varied from slightly 
shorter than the first article to over 1.5 times 
as long, the rostrum from shorter than to 
