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NO. 12 HOLTHUIS : PALAEMONIDAE OF AMERICAS, PART II 53
P. mexicanus. In the figure given by De Saussure, however, the second
leg of P. mexicanus has the carpus shorter than the chela and longer
than the palm, just like in M. acanthurus. Ortmann (1891, p. 698,
699) in his key to the species of his division Eupalaemon of the present
genus distinguishes the two forms on the shape of the rostrum. In
Palaemon mexicanus the rostrum should be longer than the scaphocerite
and strongly curved upwards at the apex. In the description of Palaemon
acanthurus (p. 721) the variability of the rostrum is pointed at by him:
it may be longer than, as long or shorter than the scaphocerite, furthermore it may be straight or more or less curved upwards. Also Smith
(1871) points to the variability in the shape of the rostrum: In young
specimens the rostum has the apex distinctly more upturned than in
older specimens, in females more than in males. This too is shown by
my material, though exceptions occur. Various not fullgrown specimens
show perfect resemblance to De Saussure's figure and description of
Palaemon mexicanus. It is therefore almost certain that De Saussure's
specimen is either a female or a not fullgrown male of Macrobrachium
acanthurus.
Palaemon dasydactylus and P. sexdentatus Streets (1871), too, are
identical with the present species. Streets himself already pointed to the
close resemblance of both his species with P. mexicanus, with which
species they subsequently were identified by Ortmann (1891). Kingsley
(1878) identifying P. dasy dactylus with P. forceps, thought P. sexdentatus a variety of P. mexicanus. The types of P. dasy dactylus were examined by me, they are present in the Museum of the Academy of
Natural Sciences at Philadelphia and are in good condition.
Macrobrachium longidigitum Bate, from an unknown locality is
identical with the present species, as is distinctly shown by Bate's description and figure. The specimens described as Palaemon (or Macrobrachium, or Bithynis) acanthurus (or forceps) from West Africa
belong to the closely related Macrobrachium macrobrachion (Herklots),
while the West American specimens referred to the present species (Von
Martens, 1869, p. p.; Kingsley, 1882; Sharp, 1893, p. p.; Bouvier, 1895;
Schmitt, 1924; Schmitt, 1933, p. p.; Coventry, 1944) belong to Macrobrachium tenellum (Smith). These specimens from Darien identified by
Nobili (1897) as Palaemon mexicanus, in reality belong to Macrobrachium panamense (p. 23). The specimens from Rio Peripa,
Ecuador reported upon by Nobili (1901) under the name Palaemon
(Eupalaemon) acanthurus var. were examined by me in the Turin
Museum. They proved to belong to a new species Macrobrachium
gallus (p. 67).
Object Description
Description
| Title | AHF-PUB-OP-12~055 |
| Type | texts |
| Format (imt) | image/tiff |
| Contributing entity | University of Southern California |
| Filename | AHF-PUB-OP-12~055.tiff |
| Full text | NO. 12 HOLTHUIS : PALAEMONIDAE OF AMERICAS, PART II 53 P. mexicanus. In the figure given by De Saussure, however, the second leg of P. mexicanus has the carpus shorter than the chela and longer than the palm, just like in M. acanthurus. Ortmann (1891, p. 698, 699) in his key to the species of his division Eupalaemon of the present genus distinguishes the two forms on the shape of the rostrum. In Palaemon mexicanus the rostrum should be longer than the scaphocerite and strongly curved upwards at the apex. In the description of Palaemon acanthurus (p. 721) the variability of the rostrum is pointed at by him: it may be longer than, as long or shorter than the scaphocerite, furthermore it may be straight or more or less curved upwards. Also Smith (1871) points to the variability in the shape of the rostrum: In young specimens the rostum has the apex distinctly more upturned than in older specimens, in females more than in males. This too is shown by my material, though exceptions occur. Various not fullgrown specimens show perfect resemblance to De Saussure's figure and description of Palaemon mexicanus. It is therefore almost certain that De Saussure's specimen is either a female or a not fullgrown male of Macrobrachium acanthurus. Palaemon dasydactylus and P. sexdentatus Streets (1871), too, are identical with the present species. Streets himself already pointed to the close resemblance of both his species with P. mexicanus, with which species they subsequently were identified by Ortmann (1891). Kingsley (1878) identifying P. dasy dactylus with P. forceps, thought P. sexdentatus a variety of P. mexicanus. The types of P. dasy dactylus were examined by me, they are present in the Museum of the Academy of Natural Sciences at Philadelphia and are in good condition. Macrobrachium longidigitum Bate, from an unknown locality is identical with the present species, as is distinctly shown by Bate's description and figure. The specimens described as Palaemon (or Macrobrachium, or Bithynis) acanthurus (or forceps) from West Africa belong to the closely related Macrobrachium macrobrachion (Herklots), while the West American specimens referred to the present species (Von Martens, 1869, p. p.; Kingsley, 1882; Sharp, 1893, p. p.; Bouvier, 1895; Schmitt, 1924; Schmitt, 1933, p. p.; Coventry, 1944) belong to Macrobrachium tenellum (Smith). These specimens from Darien identified by Nobili (1897) as Palaemon mexicanus, in reality belong to Macrobrachium panamense (p. 23). The specimens from Rio Peripa, Ecuador reported upon by Nobili (1901) under the name Palaemon (Eupalaemon) acanthurus var. were examined by me in the Turin Museum. They proved to belong to a new species Macrobrachium gallus (p. 67). |
| Archival file | hancockunpub_Volume31/AHF-PUB-OP-12~055.tiff |
