SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 543 ...

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length but nearly similar in form, palm subcylindrical, fingers
not covered with dense pubescence, partially dentate on
opposable margins, not gaping, '/2- 2 /3 as long as palm, latter
without any dense pubescence, chela less than 3 /4 as long as
carpus, palm about 2 /s as long as carpus, carpus 1 3 A times as
long as merus, without longitudinal grooves; 3rd pereopod
overreaching antennal scale by length of dactyls and x li of
propodus, propodus not profusely spinose or scaly; maximum
postorbital carapace length less than 15 mm.
RANGE.—Known only from the type locality in Sentani
Lake, Irian Jaya.
34. Macrobrachium mirabile (Kemp, 1917)
Palaemon mirabilis Kemp, 1917:227, pi. 10 [type locality: Rangoon, Burma (=
Myanmar)].
Macrobrachium mirabile.—Holthuis, 1950a: 174.
DIAGNOSIS.—Rostrum not nearly reaching level of distal end
of antennal scale, with rather high dorsal crest, rostral formula:
4-6 + 9-10/1-2, dorsal teeth subequally spaced; branchiostegal
suture not extending posteriorly beyond hepatic spine;
telson with posterior apex not overreaching posterolateral
spines; antennal scale with lateral margin straight; 1 st pereopod
with chela more than l /2 as long as carpus; 2nd pereopods
subequal in length and similar in form, palm subcylindrical,
fingers not concealed by dense pubescence, not dentate on
opposable margins, not gaping, fingers l 2 /3 times as long as
palm, latter without any dense pubescence, chela 1 3 /4 times as
long as carpus, palm less than 3 /4 as long as carpus, carpus more
than 3 A as long as merus, not longitudinally grooved; 3rd
pereopod overreaching antennal scale by length of dactyl,
propodus not profusely spinose or scaly; maximum carapace
length less than 15 mm.
RANGE.—Brackish water in the Gangetic delta, Burma
(Myanmar), Thailand, and Borneo.
REMARKS.—Kemp (1917:230, 231) obviously believed this
species to be more closely related to the species of Leander (=
Palaemon) than to those of Palaemon (= Macrobrachium), but
the presence of an hepatic spine led him to assign it to the latter
genus, in order to avoid tampering with accepted classification.
Examination of specimens from Thailand in the Smithsonian
collections indicates to us that the species does not belong in
the genus Macrobrachium, because of the form of the second
pereopods, the unusually long and slender fourth and fifth
pereopods, and the possibility that females may be larger than
males (as in most palaemonid genera except Macrobrachium.)
On the other hand, the species does not fit comfortably in
Palaemon because of the presence of an hepatic spine and
perhaps other characters. The assignment of the species to a
distinct, monotypic genus would seem to be the best solution to
the problem. Only the absence of males in our collections and
the hope that they may reveal generic characters other than
those displayed by the females has prevented us from
proposing such a genus here.
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
35. Macrobrachium natulorum Holthuis, 1984
Macrobrachium natulorum Holthuis, 1984a:164, figs. 2, 3 [type locality: Jawej
River nearTigi Lake, Wissel Lakes, Irian Jaya, Indonesia].
DIAGNOSIS.—Rostrum not nearly reaching level of distal end
of antennal scale, dorsal margin slightly sinuous, rostral
formula: 4-5 + 9-13/2-3, dorsal teeth nearly subequally
spaced; branchiostegal suture not extending posteriorly beyond
hepatic spine; telson with posterior apex not overreaching
posterior spines; antennal scale with lateral margin straight; 1st
pereopod with chela 2 /3 as long as carpus; 2nd pereopods
unequal in length and dissimilar in form; major 2nd pereopod
with palm slightly compressed, fingers concealed by dense
pubescence, dentate on opposable margins, somewhat gaping,
slightly longer than palm, palm with distal end clothed in dense
pubescence-like fingers, chela more than twice as long as
carpus, palm about as long as carpus, carpus about as long as
merus, without longitudinal grooves; minor 2nd pereopod with
fingers twice as long as palm; 3rd pereopod barely, if at all,
overreaching antennal scale, propodus neither spinose nor
scaly; maximum postorbital carapace length 25 mm.
RANGE.—Wissel Lakes region, Irian Jaya (New Guinea),
Indonesia.
36. Macrobrachium oenone (De Man, 1902)
Palaemon (Macrobrachium) oenone De Man, 1902:784, pi. 25: fig. 49 [type
locality: northern Halmahera).
Palaemon (Macrobrachium) oenone papuana J. Roux, 1927:324, fig. 2 [type
locality: Mamberamo River, northern Irian Jaya].
Macrobrachium oenone.—Holthuis, 1950a:256.
DIAGNOSIS.—Rostrum not overreaching antennal scale,
dorsal margin convex or faintly sinuous, rostral formula: 6-7 +
6-9/2-3, dorsal teeth subequally spaced; branchiostegal suture
not extending posteriorly beyond hepatic spine; telson with
posterior apex not overreaching posterolateral spines; 1st
pereopod with chela l /2 as long as carpus; 2nd pereopods
unequal in length, somewhat dissimilar in form; major 2nd
pereopod with palm somewhat compressed, fingers not
concealed by dense pubescence, dentate on opposable margins,
somewhat gaping, fingers 1—1 3 A times as long as palm, latter
without any dense pubescence, chela 2 3 /4-3'A as long as
carpus, palm l'/3-l'/2 times as long as carpus, carpus 9 /io as
long as merus, without longitudinal grooves; minor 2nd
pereopod with fingers twice as long as palm; 3rd pereopod
overreaching antennal scale by length of dactyl and l /2 of
propodus; propodus not profusely spinose or scaly; maximum
postorbital carapace length less than 20 mm.
RANGE.—Halmahera and New Guinea.
37. Macrobrachium palaemonoides Holthuis, 1950
Macrobrachium palaemonoides Holthuis, 1950a: 136, fig. 31 [type locality:
"Lake Tawar, Laulo Lake, northern Simaloer, off Sumatra" at 2°50'N,
95°50'E].
DIAGNOSIS.—Rostrum overreaching antennal scale, dorsal