Description of two new species of Physopyxis and redescription of P. lyra (Siluriformes: Doradidae)
Author
Sousa, Leandro M.
Author
Rapp Py-Daniel, Lúcia H.
text
Neotropical Ichthyology
2005
2005-12-31
3
4
625
636
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252005000400019&lng=en&tlng=en
journal article
10.1590/S1679-62252005000400019
1982-0224
5418073
03E6307C-D041-4E09-8A26-35D3936DB17F
Physopyxis cristata
,
new species
Fig. 7
Holotype
.
INPA 24325
(
22.73 mm
SL), mouth of igarapé
Zamula
,
rio Negro
,
Amazonas State
,
Brazil
(
00°51’48”S
,
62°46’44”W
),
N. L. Chao
et al.
,
20 Oct 2002
.
Paratypes
(N = 23).
Brazil
:
Amazonas
:
ANSP 180960
(2,
10.7- 11.04 mm
SL), same data as holotype
.
INPA 20193
(2,
13.38- 14.42 mm
SL),
rio Caurés
,
rio Negro
basin
.
INPA 20194
(1,
12.64 mm
SL),
rio Caurés
,
rio Negro
basin
.
INPA 21915
(1,
10.64 mm
SL), same data as holotype
.
INPA 21916
(1,
11.18 mm
SL), igarapé
Zamula
,
rio Negro
basin
.
INPA 25063
(1,
10.98 mm
SL),
rio Cuiuni
,
rio Negro
basin
.
MZUSP 76209
(2, not measured), beach of paraná do
Jacaré
,
rio Negro
basin
.
MZUSP 76210
(2, not measured),
Urumari
beach, two hours upstream
Barcelos
,
rio Negro
(
00°58’S
,
62°57’W
)
.
MZUSP 76211
(1, not measured),
Urumari
beach, two hours upstream
Barcelos
,
rio Negro
(
00°58’S
,
62°57’W
)
.
Roraima
:
INPA 25061
(1,
10.93 mm
SL), igarapé
Corumbaú
,
rio Branco
,
rio Negro Basin
.
INPA 25062
(7 + 2 c&s, not measured), same data as INPA
25061.
Diagnosis.
Physopyxis cristata
can be easily distinguished from its congeners by possessing an incomplete lateral line that ranges between five and twelve lateral plates; lateral plates weakly ossified, externally visible only by posteriorly-oriented spine; tips of neural spines exposed, perforating skin middorsally along posterior portion of body, forming a crest between dorsal and caudal fins.
Description.
Morphometric data summarized in
Table 3
. Largest specimen examined measures
22.73 mm
SL. Body slightly slender, moderately deep with greatest body depth at origin of dorsal fin (body depth 27-30% of SL). Top of head and nuchal plates roof shaped, with bony ornamentation arranged in shallow grooves concentrated along nuchal shield crest and borders. Anterior nostril tubular and placed near border of snout. Posterior nostril nearer to orbit than to snout. Snout short, its length twice orbital diameter. Lacrimal bone well developed, dorsal and ventral margins serrated with conspicuous spines. Mouth terminal. Barbels simple, long, slightly compressed, with papillae along inferior surfaces. Maxillary barbel reaching to or surpassing tip of postcleithral process. Outer mental barbel reaching point of insertion of pectoral spine. Inner mental barbel slightly shorter than outer mental barbel.
Scapular girdle as in
Physopyxis lyra
. Cleithrum laterally expanded and visible from above, sculptured with shallow grooves up to postcleithral process. Postcleithral process relatively short, its tip reaching to or slightly surpassing vertical through dorsal-spine origin. Coracoid process very long, slender (larger than postcleithral process), with well defined straight longitudinal grooves and ridges along its entire length. Tip of coracoid process pointed, not expanded.
Dorsal and pectoral spines strongly ossified, serrated and grooved as in
P. lyra
.
Lateral line incomplete and asymmetric, ranging from five to 12 lateral plates. Lateral plates weakly developed and embedded beneath skin, with only retrorse spines visible from outside. Tips of neural spines of vertebrae visible externally, emerging middorsally in posterior portion of body, forming crest between dorsal and caudal fins. Some specimens with tips of vertebral hemal spines visible externally, emerging midventrally on caudal peduncle.
Table 3.
Descriptive morphometrics and counts of
Physopyxis cristata
(N = 10). SD = Standard deviation. Hol = Holotype.
|
Hol
|
Range
|
Mean (SD)
|
| Standard length (mm) |
22.73 |
10.64–22.73 |
| Total length (mm) |
30.17 |
13.51–30.17 |
|
Percent of Standard length
|
| Pre-dorsal length |
40.65 |
39.40–41.11 |
40.04 (0.63) |
| Dorsal fin base |
12.76 |
10.76–13.66 |
12.6 (0.99) |
| Body depth |
28.68 |
27.17–30.14 |
29.03 (1.03) |
| Dorsal-adipose fin length |
26 |
22.37–26.0 |
23.98 (1.22) |
| Adipose-caudal fin length |
9.85 |
9.85–14.38 |
11.54 (1.52) |
| Pre-pectoral length |
29.3 |
26.27–29.70 |
28.52 (1.08) |
| Pre-pelvic length |
50.68 |
45.65–52.77 |
49.93 (2.41) |
| Pre-anal length |
63.22 |
60.84–65.35 |
62.97 (1.51) |
| Anal fin base |
22.88 |
22.72–25.04 |
23.48 (0.77) |
| Caudal peduncle length |
7.83 |
4.92–8.46 |
7.03 (1.08) |
| Caudal peduncle depth |
10.07 |
9.42–10.62 |
10.06 (0.37) |
| Lateral plate depth |
4.14 |
2.35–4.14 |
3.15 (0.68) |
| Superior lateral plate portion depth |
- |
- |
- |
| Inferior lateral plate portion depth |
- |
- |
- |
| Body depth at 4th plate |
- |
- |
- |
| Dorsal spine length |
29.3 |
26.63–35.51 |
31.22 (3.39) |
| Pectoral spine length |
40.61 |
34.57–41.48 |
38.33 (2.65) |
| Head length |
28.2 |
26.64–29.27 |
28.11 (0.8) |
| Maxillary barbel length |
42.89 |
29.07–42.89 |
36.04 (5.79) |
| Scapular girdle width |
38.36 |
38.36–42.11 |
39.6 (1.29) |
| Postcleithral process length |
8.8 |
5.93–10.19 |
8.35 (1.57) |
| Coracoid process length |
21.21 |
19.66–22.84 |
20.97 (1.04) |
| Pectoral girdle mesial suture |
18.52 |
17.71–20.02 |
18.71 (0.76) |
| Dist between coracoid process tips |
22.44 |
16.49–22.44 |
20.03 (1.78) |
| Coracoid width |
28.16 |
24.37–28.62 |
26.81 (1.54) |
|
Percent of Head length
|
| Head depth |
88.3 |
85.10–96.34 |
91.11 (3.75) |
| Orbital diameter |
13.42 |
13.42–25.16 |
20.89 (3.18) |
| Interorbital width |
48.05 |
48.05–56.95 |
54.01 (3.18) |
| Mouth inner width |
39.01 |
38.95–47.45 |
42.57 (2.99) |
| Snout length |
35.41 |
32.12–38.38 |
34.48 (2.17) |
|
Counts
|
Mode
|
| Dorsal fin rays |
I+5 |
I + 4–5 |
I+5 |
| Pectoral fin rays |
I+4 |
I + 3–4 |
I+4 |
| Pelvic fin rays |
7 |
7 |
7 |
| Anal fin rays |
15 |
13–17 |
15 |
| Caudal fin rays |
11 |
10–12 |
12 |
| Dorsal spine serrae |
5 |
4–7 |
5 |
| Lateral plates |
10 |
5–12 |
10 |
Dorsal-fin rays I,4 or I,5. Dorsal-fin origin situated at anterior third of body. Pectoral-fin rays I,4. Pectoral fin located at vertical through branchial opening. Pelvic-fin rays 7. Pelvic fin inserted at vertical through coracoid process tip, approximately at middle of body. Tip of pelvic-fin rays reaching to anal-fin origin.Anal fin with 15 rays.Adipose fin small, membranous. Caudal fin truncate to slightly emarginate, with 8,4 rays.
Color in alcohol.
Physopyxis cristata
has same color pattern as described for
P. lyra
.
Distribution.
This species has been recorded only from middle portion of the rio Negro basin (Amazonas drainage), Amazonas State,
Brazil
.
Etymology.
The name
cristata
, from Latin
cristatus
, meaning crested, in allusion to externally visible series of emergent neural spines.
Habitat.
Some specimens included in
type
series were found in accumulated leaf litter, suggesting habitat similar to that observed in
P. lyra
. Dwarf cichlids of the genus
Apistogramma
and juvenile specimens of
Amblydoras
were collected with specimens of
P. cristata
.