FIGURE 1.Chelorchestia darwini
(Müller, 1864)
, male 8.7 mm, MNRJ 19501. A, head; F, gnathopod 1; G, gnathopod 2; H, pereopod 3; I, pereopod 4. Female, 6.3 mm, MNRJ 17000. B, left mandible; C, right lacinia mobilis; D, maxilliped; E, detail of maxilliped. Scale bars: A, F–I, 0.5 mm; B– D, 0.1 mm; E, 0.05 mm.
Material examined
.
Alagoas
— Mundaú Lagoon, Maceió, AL,
2 males
, A. Lemos de Castro col.,
02/VIII/1978
,
MNRJ
19502.
Bahia
Jacuruna river, BA,
1 male
,
30/XI/1978
,
MNRJ
19504.
Rio de Janeiro
— Guapimirim Mangrove (APA), Guapi river, Guapimirim, RJ,
6 females
,
2 male
juveniles and
2 males
, C. Serejo & A. de Souza col.,
03/IV/2003
,
MNRJ
19508; Pedra de Guaratiba, RJ, mangrove, in
Spartina
sp.,
2 females
,
2 juveniles
males and
1 male
, Y. Wakabara col.,
VI/1997
,
MNRJ
19505; Gargaú mangrove, Campos, RJ, in
Echornia
sp.,
1 male
and
1 female
, A. Bustamante col.,
6–13/IX/2000
,
MNRJ
18745.
São Paulo
— Cananéia, Mangrove,
1 juvenile
male, Y. Wakabara col.,
14/IX/1981
,
MNRJ
15114; Cananéia Mangrove, A. S. Tararam col.
VII/1988
to
I/1989
,
2 females
,
MNRJ
15075;
1 female
,
MNRJ
15076;
1 male
and
4 females
,
MNRJ
15077;
1 juvenile
male and
5 females
,
MNRJ
15079;
1 male
,
3 juvenile
males, and
10 females
,
MNRJ
15080;
1 juvenile
male and
3 females
,
MNRJ
15082;
1 female
,
MNRJ
15083;
1 male
and
2 females
,
MNRJ
15085;
1 female
,
MNRJ
15086.
Paraná
— Correias river, Paranaguá Bay, 25º31S 48º29W, PR, in mangrove, R. Bogrim, col., 1996,
1 female
,
MNRJ
17000; Boquerá river, Paranaguá Bay, 25º27S 48º32W, PR,
1 juvenile
male, in mangrove,
MNRJ
18744; Cachoeira river,
Antonina Bay
, 25º24S, 48º43W, PR, in mangrove,
1 male
,
MNRJ
19501; Cotinga Island, Paranaguá Bay, 25º32S, 48º26W, PR,
1 male
juvenile, mangrove,
MNRJ
19503; Corisco Island,
Antonina Bay
, 25º24S, 48º44W, PR, in mangrove,
1 female
,
MNRJ
19506; Guaramiranga de Dentro
Island
,
Antonina Bay
, 25º25S, 48º39W, mangrove,
1 female
,
MNRJ
19507.
Diagnosis
. Antenna 2 reaching 2/5 of body length. Adult male gnathopod 2 chelate. Uropod 1, peduncle with interramal robust seta; outer ramus lacking marginal setae.
Description
. Male,
11.9 mm
. Antenna 1 (
Fig. 1
A) reaching 2/3 of peduncle article 4 of antenna 2. Antenna 2 slender (
Fig. 1
A), reaching 2/5 of body length; article 5 of peduncle a little longer than article 4; first three articles of flagellum fused, flagellum with about 12 articles. Eyes large. Mandible with left lacinia mobilis 4dentate, sometimes with minute fifth teeth; right lacinia bifid (
Fig. 1
B–C). Maxilla 1, inner plate with two distal plumose setae; outer plate with 9 dentate robust setae, palp reduced and 1articulate. Maxilla 2, inner plate with several distal setae and two larger proximal plumose seta, being one seta larger than the other; outer plate a little larger than inner plate. Palp of maxilliped robust and 4articulate, fourth article strongly reduced (
Fig. 1
D–E).
Gnathopod 1 (
Fig. 1
F), merus posteriorly produced into a pointed process; carpus and propodus with well developed posterior lobe. Gnathopod 2 (
Fig. 1
G), basis anterior margin with 0 to 3 tubercles, carpus fused with propodus, chelate in adult males. Pereopod 3 a little longer than pereopod 4, dactylus of pereopod 4 not thickened (
Fig. 1
H–L). Pereopod 5 shorter than pereopods 6–7 (Fig. 2A–C). Pereopod 7 (Fig. 2C), coxa with anterodistal corner forming a right angle. Dactylus of pereopods 3–7 simplidactylate.
Uropod 1 (Fig. 2D), peduncle with distal lateral robust seta, inner ramus with three marginal robust setae; outer ramus lacking marginal setae. Uropod 2 (Fig. 2E), peduncle and rami subequal in length, each ramus with 2 marginal robust setae. Uropod 3 (Fig. 2F), peduncle with a long, robust, subdistal seta; ramus about half of peduncle. Telson long, medial line poorly observed, each side with one or two lateral robust setae and one distal robust setae.
FIGURE 2.Chelorchestia darwini
(Müller,
1864), male 8.7 mm, MNRJ 19501. A,
pereopod 5; B,
pereopod 6; C, pereopod 7; D, uropod 1; E,
uropod 2; F, uropod 3; G, telson. Scale
bars: A–C, 0.5
mm; D, E, G, 0.2 mm; F, 0.1 mm.
FIGURE 3.Chelorchestia darwini
(Müller, 1864)
, female, 6.3 mm, MNRJ 17000. A, gnathopod 1; B, gnathopod 2; C–F, oostegites 2–5 respectively. Male, 8.5 mm, MNRJ 19502. G, gnathopod 2. Male, 9.8 mm, MNRJ 19508. H, gnathopod 2. Male. I–J, gnathopod 2 (from Müller, 1869). Scale bars: A, 0.2 mm; B, 0.3 mm; C–H, 0.5 mm.
Female,
6.3 mm
. Antenna 2 as in males, but flagellum without fused articles. Gnathopod 1 (
Fig. 3
A) distinctly subchelate. Gnathopod 2 (
Fig. 3
B), basis not expanded anteriorly; merus, carpus and propodus with tiny setae on posterior lobe, propodus oval. Oostegites 2–5 oval (
Fig. 3
C–F), oostegites 2–4 about 3.5 times longer than wide, oostegite 5 a little shorter than others, about 2.5 times longer than wide.
Variation on male gnathopod 2
. This appendage shows a great variation during the development of the specimen, that can make confusion in the identification within the genus
Chelorchestia
. The basis show anteroproximal tubercles varying from 0 to 3 (
Figs. 1
G; 3G–H). Otherwise, the palm, which is transverse in early stages, has a medial strong concavity and the palmar corner develops into a process that will give a chelate appearance in adults male gnathopod 2 (
Fig. 1
G, 3H). In some specimens (
8.5 mm
) (
Fig. 3
G), there are two shallow concavities and the palmar process bears two rounded humps.
Remarks.Bousfield (1984)
erected the genus
Chelorchestia
for one of the talitrid groups that inhabit mainly tropical mangrove and
Spartina
marshes or other low salinity habitats. Besides
C. darwini
, three other species of the genus are known:
C. costaricana
(Stebbing, 1906)
from mangrove swamps of
Costa Rica
;
C. vaggala
(
Bowman, 1977
)
from the Galapagos Island; and the recently described
C. forcepsSmith
&
Heard
, 2001 from southeastern coast of
United States
.
Chelorchestia darwini
was originally briefly described by Fritz
Müller (1864)
in his notable work in defense of Darwin evolutionary theory. Fritz Müller lived and worked in Desterro, nowadays Florianópolis, the capital of Santa Catarina state. In the time Müller was in
Brazil
(from 1852 until 1897) he also worked as a naturalist for the Museu Nacional, Rio de Janeiro. Unfortunately, no
type
material was deposited at the Museu Nacional, and there is no information where these
types
may be deposited. Taking this into account,
C. darwini
is herein redescribed and compared with other species of the genus.
Ruffo (1956)
also redescribed
C. darwini
with material from Cananéia, São Paulo,
Brazil
. However,
Ruffo (1956)
found only males with gnathopod 2 of
type
B (
Fig. 3
G), and suggested that these specimens could be possible juveniles of a latter mature male stage with gnathopod 2 of
type
A (
Fig. 3
H).
Müller (1869)
also noticed the same variations on male gnathopod 2 (
Fig.
3
I, J), and also concluded that both forms belong to the same species, as the females did not vary. In this study, I found samples with females and only males
type
A, even examining material from Cananéia, and never found sympatric males of both
types
. Besides the notable difference of the gnathopod 2, the antenna 2 is longer in specimens with gnathopod 2
type
B, reaching half of body length, suggesting that these are two distinct species. However, I prefer wait to examine more material, especially females corresponding to male
type
B, before making changes to the species taxonomy.
Chelorchestia forceps
is a similar species to
C. darwini
. Characters that could be useful to distinguish these species, as the number of tubercles on basis of male gnathopod 2, and the number of robust setae on the telson, showed variation in the examined specimens. The single clear distinction between
C. forceps
and
C. darwini
is the presence in the former of two robust setae, one dorsal and one ventral, at the articulation of propodus and dactylus of pereopods 3–4.
Chelorchestia darwini
has two long setae dorsally and one robust setae ventrally (
Fig.
1
I, L) in this position. Comparison between material of
C. forceps
and
C. darwini
would elucidate better the status of these taxa, which maybe synonyms.
The other two species of
Chelorchestia
,
C. vaggala
and
C. costaricana
are distinguished from
C. darwini
as follows: the male gnathopod 2 of
C. vaggala
is subchelate with a transverse palm (
Bowman, 1977
) and
C. costaricana
has a long antenna 2, reaching more than half of body length and a longer propodus of male gnathopod 2, about twice as long as wide (
Stebbing, 1906b
). For more comments on the genus see
Smith and
Heard
(2001)
.
Type
locality.
Brazil
, possibly Santa Catarina.
Distribution.Brazil
: from Alagoas to Santa Catarina.
Ecology.
Found in mangrove and estuarine areas, on mud or on the vegetation. In same areas this species lives in sympatry with
Platorchestia monodi
and the identification of the females may be confuse (see key).