Psilotris amblyrhynchus, a new seven-spined goby (Teleostei: Gobiidae) from Belize, with notes on settlement-stage larvae

10 Pages·1999·4.8 MB·

by  S G Smith

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
112(2):433-442. 1999.
Psilotris amblyrhynchus^ a new seven-spined goby
(Teleostei: Gobiidae) from Belize, with notes on
settlement-stage larvae
David G. Smith and Carole C. Baldwin
Department of Vertebrate Zoology, MRC 159, National Museum of Natural History,
Smithsonian Institution, Washington, D.C. 20560-0159, U.S.A.,
email: [email protected]; [email protected]
—
Abstract. Psilotris amblyrhynchus is described from one adult and one ju-
Bow
venile collected in shallow waters in the vicinity of Carrie Cay, Belize,
Central America. Settlement-stage larvae of the new species were collected in
a stationary plankton net and are used to augment the description; two of these
were reared through metamorphosis. Psilotris amblyrhynchus is distinguished
from other western Atlantic seven-spined gobies on the basis of meristic fea-
tures and pigment pattern. Psilotris is one of 15 genera assigned by Birdsong
et al. (1988) to the ''Gobiosoma group," but the genus is not defined on the
basis of derived characters. Assignment of the new species to Psilotris is based
on its having separate pelvic fins, seven spines in the first dorsal fin, no scales,
and no head pores. None of these characters by itself is unique within the
Gobiosoma group to Psilotris, and the configuration of the pelvic fins is highly
variable among gobies. Our inability to diagnose Psilotris cladistically, along
with our discovery of resemblances between larvae of Psilotris amblyrhynchus
and those of another western Atlantic member of the Gobiosoma group, Nes
longus, suggest that generic concepts within the Gobiosoma group should be
reassessed.
The gobiid genus Psilotris is distin- they cannot be assigned to any of the five
guished from all other western Atlantic recognized species,
genera by the following combination of
characters: seven spines in the first dorsal Methods
fin; pelvic fins separate; scales absent; head
pores absent. These characters, while of Counts and measurements follow Hubbs
&
questionable phylogenetic significance, Lagler (1958). Institutional abbreviations
conveniently characterize the included spe- follow Leviton et al. (1985). The dorsal-fin
cies. Five species are currently recognized: formula was proposed by Birdsong et al.
the type species, Psilotris alepis Ginsburg, (1988) to describe the relationship between
1953; P. batrachodes Bohlke, 1963; P. eel- the dorsal-fin pterygiophores and the neural
sus Bohlke, 1963; P. kaufmani Greenfield interspaces of the vertebral column. The
et al., 1993; and P. boehlkei Greenfield, first digit represents the neural interspace
1993. They are distinguished from one an- into which the anteriormost pterygiophore
other by color pattern, fin-ray counts (Table inserts. The digits following the hyphen de-
2), and a few proportional measurements, note the number of pterygiophores that in-
The specimens described here possess the sert into each subsequent interspace. The
four distinguishing features of Psilotris, but holotype was x-rayed to obtain vertebral
—
434 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
ii ^
Fig. L Psilotris amblyrhynchus, holotype, USNM 321019, 34.0 mm SL.
and fin-ray counts. For larvae, these counts 14.2), Caribbean, BeUze, shallow spur and
were obtained by clearing several speci- groove just east of Carrie Bow Cay, ca. 20
mens in trypsin and counterstaining them ft (6.1 m), 9 Sep 1997, C. C. Baldwin and
with alizarin red and alcian blue. Adult and D. G. Smith. Larvae: all collected in a sta-
juvenile specimens of the new species were tionary plankton net on seaward side of
collected with rotenone or quinaldine. Lar- Carrie Bow Cay, Belize; USNM 350086 (1,
USNM
vae were collected in a 1.0 by 0.5-m rect- 11.5), 10 Jun 1993, 2130 hr;
angular plankton net with 505 |xm mesh, 350087 (2, 11.5), 13 Jun 1193, 2130 hr,
fished passively over the reef flat by sus- cleared and stained; USNM 350088 (1,
pending it from a pier on the seaward side 13.0), 14 Jun 1993, 2330 hr; USNM
of Carrie Bow Cay, BeHze. Selected cap- 350089 (1, 12.5), 20 Jun 1993, 2100-2330
tured larvae were anesthetized with MS- hr; USNM 350090 (1, 11.5), 20 Jun 1993,
222, examined under a dissecting micro- 2130 hr; USNM 350091 (1, 11.0), 21 Jun
scope, then reared in small, nylon-mesh 1993, 2300 hr; USNM 350092 (1, 14.0),
breeder traps set in a raceway in a flow- 19-22 Jun 1993, reared; USNM 350093 (1,
through seawater system. Reared larvae 16.8), 28 Jul 1994, reared; USNM 350094
were fed cultured brine shrimp. (2, 10.5-11.5), 8 Aug 1994, cleared and
stained.
Psilotris amblyrhynchus new species Comparative material.—Larvae of Nes
B
Figs. 1, 2, 3A, longus, all collected in a stationary plank-
Holotype,—VS^<m. 321019 (34.0 mm ton net on seaward side of Carrie Bow Cay,
USNM
SL), Belize, western Caribbean, between BeHze: 350189 (1, 11.0), 23 Jul
Carrie Bow Cay and Twin Cays, lagoon 1992, 2230-2300 hr; USNM 350190 (2,
USNM
"shot hole," 15-20 ft (4.6-6.1 m), 17 Sep 10.0), 27 Jul 1992, 2000-2030 hr;
1990, G. D. Johnson,—et al. 350191 (1, 11.0), 27 Jul 1992, 2230n2300
USNM USNM
Other specimens. 347250 (1, hr; 350192 (3, 9.5), 16 Jun 1993,
USNM mm
Fig. 2. Psilotris amblyrhynchus, larva, 350088, 13.0 SL.
VOLUME NUMBER
112, 2 435
^
USNM
Fig. 3. Pelvic fins: development from larva to juvenile. A. Psilotris amblyrhynchus, 350088, larva,
13.0 mm SL. B. Psilotris amblyrhynchus, USNM 347250, juvenile, 14.2 mm SL. C. Nes longus, USNM 350194,
larva, 10.5 mm SL. D. Nes longus, USNM 350197, reared juvenile, 16.5 mm SL.
A
436 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
USNM
2030 hr; 350193 (4, 9.0-11.0), 20 end of jaw below posterior half of eye.
Jun 1993, 2000-2030 hr, three specimens Teeth slender, conical, slightly recurved,
USNM
cleared and stained; 350194 (1, widely spaced, uniserial. Gill opening re-
USNM
10.5), 2 Sep 1996; 350195 (1, 10.5), stricted, not extending past base of pectoral
USNM
5 Sep 1996; 350196 (7, 9.5-17.0), fin. Second dorsal and anal fins relatively
USNM
28 Jul 1994, reared; 350197 (5, long, the base of each longer than caudal
USNM
15.0-19.3), Sep 1997, reared; peduncle. Anteriormost spine of first dorsal
350198 (1, 9.5), 12 Jun 1993, 2100 hr, fin greatly elongate, reaching middle of
USNM
cleared and stained. Psilotris alepis: base of second dorsal fin when appressed.
mm
123231 (holotype, 13 SL), St. Croix, Caudal fin elliptical, middle rays much lon-
Virgin Islands, 8 Apr 1937. Psilotris ba- ger than those above and below. Pelvic fins
USNM
trachodes: 274946 (1, 13.0), Carrie almost completely separate, only a small
Bow Cay, Belize, depth 12-25 ft (6-8 m), basal membrane connecting the inner rays
USNM
10 Jun 1981; 317025 (1, 17.8), Ca- of the two sides (Fig. 3B).
ribbean, Tobago, Sisters Rocks, depth to 60 Measurements in mm, with proportions
ft (18 m), 14 Sep 1990; USNM 317026 (3, in parentheses: SL 34.0, preanal length 19.7
7.0-8.5), Caribbean, Tobago, windward (58% SL), head length 10.0 (29% SL),
side of Little Tobago Is., depth 60 ft (18 snout length 2.2 (22% head length), eye di-
USNM
m), 7 Sep 1990; 317480 (1, 15.5), ameter 2.5 (25% head length), interorbital
patch reef south of Carrie Bow Cay, Behze, width 0.3 (3% SL), upper-jaw length 4.8
depth 20-30 ft (6-9 m), 26 Mar 1987. Psi- (48% head length), depth at dorsal-fin ori-
lotris boehlkei: ANSP 124619 (3 paratypes, gin 5.1 (15% SL), depth at anus 4.5 (13%
17.5-18.2), St. Barthelmy, West Indies, Port SL), least depth of caudal peduncle 3.5
de Gustavia, off rocky cUffs just S. of Anse (10% SL), length of base of second dorsal
Galet, depth 60-65 ft (10.3-19.8 m), 14 Jul fin 8.6 (15% SL), posterior end of dorsal
1965. Psilotris celsus: ANSP 133274 (4, fin to origin of caudal fin 3.4% 10% SL,
20.0-26.0), Bermuda, between Sinky and base of anal fin 6.7 (20% SL), pectoral-fin
Cross Bays, off Sonesta Beach, 9.1-10.6 m, length 8.6 (25% SL), caudal-fin length 9.7
30 Jul 1975. Psilotris kaufmani: ANSP (29% SL), pelvic-fin length 5.8 (17% SL).
131712 (2 paratypes, 15.0-16.5), Jamaica, Meristic features: dorsal-fin rays Vn+12,
Discovery Bay, depth 130 ft (40 m), 16 Jun anal-fin rays 11, pectoral-fin rays 17, bran-
1974. Gobulus myersi: USNM 347348 (3, chiostegal rays 5, vertebrae 11 + 16 = 27,
22-25), BeUze, Pelican Cays, Manatee Cay, dorsal-fin formula 3-221110.
depth 1-3 ft —(0.3-1 m), 19 Oct 1997). Color in alcohol: Ground color pale yel-
A
Diagnosis. species of Psilotris, as lowish brown, with dusky markings as fol-
currently construed, with 11-12 elements in lows: diffuse dark spot on cheek below eye;
the second dorsal fin; 9-11 anal-fin rays; dark oblique streak from just behind oper-
pale ground color with a series of dusky cle to dorsum directly above pectoral base
blotches on side of body; small, distinct, and before dorsal origin; a diffuse spot on
dark spots on dorsal-fin rays; three narrow, pectoral base; approximately 16 diffuse
oblique bars on caudal fin; first dorsal spine dark saddles, irregular and uneven in inten-
elongate in adults. — sity, from nape to base of caudal fin; ap-
Description of holotype (Fig. 1). proximately seven diffuse midlateral
moderately elongate goby without scales or blotches on body between pectoral fin and
head pores. Snout short and blunt, anterior base of caudal fin, with smaller blotches in
profile ofhead steep, no rostral frenum. Eye between; discrete, small, dark spots on dor-
large, its diameter greater than snout length; sal-fin spines and rays; three oblique dark
interorbital space very narrow. Both nostrils bars on caudal fin, oriented anterodorsal to
tubular, the anterior one longer. Posterior posteroventral.
1
VOLUME NUMBER
112, 2 437
—
Table 1. Meristic characters for specimens ofPsilotris amblyrhynchus. '^ = cleared and stained. " = x-rayed.
USNM SL in mm Dorsal rays Anal rays Pectoral rays Vertebrae
321019'' 34.0 VII + 12 11 —17 11 + —16 = 27
347250 14.2 Vll + 11 10 —
350092 14.0 VII + 11 9 —17 —
350093 16.8 VII + 11 10
350087^ 11.5 VII + 12 11 19 11 + 16 = 27
350087^ 11.5 VII + W12 11 19 11 + 16 = 27
350094'^ 11.0 VII + 11 18 11 + 16 = 27
350094'^ 11.5 VII + 12 10 18 11 + 16 = 27
'Eleven rays but 12 pterygiophores.
—
Other specimens. Only one adult spec- toral-ray counts obtained were also higher
imen, the holotype, is known, and the de- in the cleared and stained specimens (18-
scription is based on it. We have also col- 19) than in the alcohol specimens (17), sug-
lected 12 immature specimens, including a gesting to us that we may be undercounting
small, field-caught juvenile and 11 larvae, the fin rays in gross examination.
two of which were reared through transfor- The field-caught juvenile (USNM
mm
mation. None of these specimens has the 347250, 14.2 SL) was photographed
full complement of adult characters, and we shortly after capture and had the following
therefore do not designate them as para- color pattern: a few melanophores on side
types. Nevertheless, they do provide addi- of opercle and on base of pectoral fin; one
tional meristic data that help characterize melanophore immediately above opercle on
the species. Four of the larvae were cleared right side; one or two melanophores behind
and stained, and their counts are presented eye and on top ofhead above brain; a single
in Table 1, along with counts from the field- small melanophore on ventral midline just
caught juvenile and the two transformed behind anal fin; a small melanophore on
larvae. Of the eight specimens for which fifth dorsal spine; a few small melano-
counts are available, all have seven spines phores on snout and upper jaw; three indis-
in the first dorsal fin. Four specimens have tinct yellow stripes on head, originating
12 elements in the second dorsal fin, and from upper, middle, and lower margin of
four have 1 1. In one of the latter, however, eye and extending approximately to poste-
the penultimate pterygiophore does not sup- rior end of opercle; a few indistinct yellow
port a ray; the specimen thus has 12 pter- spots along base—of dorsal fin.
ygiophores but only 11 rays. Fin rays can Development. The settlement-stage lar-
be difficult to count in small specimens, es- vae (Fig. 2) are characterized by a large,
pecially when the fin is depressed, as it is very conspicuous, expanded melanophore
in most of the specimens. The only way to midventrally over the posterior end of the
obtain unambiguous counts is to x-ray the anal fin. There is very little other pigment,
specimen (if it is large enough) or to clear only some internal melanophores on the
and stain it. Of the five specimens subjected dorsal surface of the gas bladder and at the
to one of these techniques, four have 12 posterior end of the intestine, and a dark
second-dorsal elements, and the fifth has 1 midventral streak immediately before the
rays but 12 pterygiophores. Four of these pelvic fin. The caudal fin is truncate rather
five also have 11 anal-fin rays. The three than elliptical. The pelvic fins are largely
specimens that were simply counted by united, the rays of the two sides nearly par-
gross examination have 11 second dorsal- allel rather than sharply diverging (Fig.
fin elements and 9-10 anal rays. The pec- 3A). The membrane connecting the inner-
438 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASfflNGTON
—
Table 2. Meristic characters in species of Psilotris.
Species Dorsal rays ^nal rays Pectoral rays
P. alepis VII + 10 9 15
P. batrachodes VII + 9-10 7-8 16
P. boehlkei VII + 10-11 10 16-18
P. celsus VII + 10-11 9-11 16-17
P. kaufinani vn + 10-11 10-11 16-19
P. amblxrhxnchus VII + 11-12 9-11 17-19
most rays of the two sides extends approx- the vicinity of Carrie Bow Cay on the bar-
imately Vs to Vi of the way from the base to rier reef in Belize, western Caribbean
the tip. There is no frenum connecting the (16°48'N, 88°05'W). The holotype was col-
spines, however. The largest of the larvae lected between Carrie Bow Cay and Twin
collected in the plankton net are about 11.5 Cays in one of a series of "shot holes" cre-
mm
SL. The 14.0-mm reared specimen still ated by seismic sounding. The habitat was
has the conspicuous ventral melanophore, described as an open sand patch in beds of
but it is smaller relative to the size of the turtle grass (Thalassia testudineum) at a
body. The pelvic fins appear more diver- depth of 15-20 feet (4.5-6.1 m). The field-
gent, and the membrane connecting the me- caught juvenile was taken from the shallow
dial rays is greatly reduced, extending not spur and groove reef complex just seaward
more than about an eighth of the distance of Carrie Bow Cay at a depth of approxi-
from the base of the rays to their tips. The mately 20 feet (6.1 m).
—
caudal fin is more elongate, but the middle Etymology. From the Greek amblys,
rays are not greatly prolonged. The 16.8- blunt, obtuse; and rhynchos, snout, muzzle.
mm
reared specimen retains the midventral In reference to the blunt anterior profile of
melanophore, but it is even less conspicu- the head. To be treated as a noun in appo-
A
ous than in the 14.0-mm specimen. few sition.
melanophores are present along the base of
the dorsal fin, but no other pigment is vis- Key to the species of Psilotris
ible. The pelvic fins are almost completely (modified from Greenfield, 1993)
separate, and they diverge strongly. The
membrane connecting the medial rays is re- la. Pectoral fin with dark brown to
stricted to the base of the rays. The caudal black bar running dorsoventrally at
fin is rounded, although the elongation of a posterior angle across fin; dorsal
the middle rays is still not extreme. The first and caudal fins also with dark bars;
dorsal spine is not elongate. The field- anal-fin elements 7 or 8 (usually 7);
mm
caught juvenile, although smaller (14.2 second dorsal-fin elements 9-10
SL) than the larger of the two reared spec- (nearly always 9) .... P. batrachodes
imens, is slightly more developed. The ven- lb. Pectoral fins lacking bar running
tral melanophore is still present but is small dorsoventrally at a posterior angle
and contracted. Definitive pigment as de- across fin, fin is bicolored (upper
scribed above is beginning to appear. The half black) or unpigmented; anal-
pelvic fins are separate and diverge strongly fin elements 8-1 1 2
(Fig. 3B). The caudal fin has still not at- 2a. Pectoral-fin rays 15; anal-fin ele-
tained the elongation seen in the holotype, ments 8—9 P. alepis
and the first dorsal spine is—not elongate. 2b. Pectoral-fin rays 16—19; anal-fin el-
Distribution and habitat. Psilotris am- ements 9-1 1 3
blyrhynchus is currently known only from 3a. Caudal fin with 3 oblique, dark
.
VOLUME 112, NUMBER 2 439
bars; snout very short and blunt, ermannichthys and Pariah. They excluded
with steep anterior profile; second Parrella, Microgobius, and Bollmannia
dorsal-fin elements 11-12 from their analysis of relationships because
P. amblyrhynchus ''Parrella is a composite and the other two
3b. Caudal fin without 3 oblique, dark are only distantly related" (Bohlke & Rob-
bars; snout more acute, with flatter ins 1968:146). The resulting diagram (Fig.
anterior profile; second dorsal-fin 4) expressed Bohlke & Robins's concept of
elements 10-1 1 4 relationships among the 16 genera and five
4a. Pectoral fin bicolored, dark brown subgenera. This is not a classification based
to black on upper 9-11 rays and on cladistic methods, which had not yet
membranes and white below; anal- come into wide use, and the genus Gobio-
fin elements 10-11 (usually 11) . soma as construed by Bohlke & Robins is
P. kaufmani a classic paraphyletic group. Nevertheless,
4b. Pectoral fin not bicolored; anal-fin by resurrecting Austrogobius, Elacatinus,
elements 9-11 (usually 10) 5 Garmannia, and Tigrigobius, one can ex-
5a. Posterior end ofjaw extending past tract a generic phylogeny from the diagram,
posterior margin of pupil; caudal even though the characters on which it is
peduncle slender (80-89 thou-
based are not shown, and this phylogeny
sandths of SL); snout short (44-55
can serve as a testable hypothesis.
thousandths of SL) P. boehlkei
Birdsong (1975:180), although still not
5b. Posterior end ofjaw not extending
using phylogenetic methods, considered the
past posterior margin ofpupil; cau-
American seven-spined gobies to be a "nat-
dal peduncle deeper (greater than
ural assemblage," based largely on verte-
92 thousandths of SL); snout lon- bral number (11 + 16-17) and dorsal-fin
ger (greater than 55 thousandths of
formula (3-221110), characters that he ob-
SL) P. celsus
served to be "extremely stable". with
. .
many groups of gobioids." He placed the
Comparison and Relationships 17 genera from Bohlke & Robins's (1968:
51) key, plus Evermannichthys Pariah, and
"Anyone who has attempted to identify ,
Palatogobius, in the tribe Gobiosomini
the naked or partially scaled Atlantic gobies
(Birdsong 1975:182, properly spelled Go-
in and around the genera Gobiosoma and
biosomatini). He noted that the ''Gobioso-
Garmannia will appreciate the difficulty ex-
perienced in placing even generically any ma group" is united by a distinctive char-
specimen." With those words, Bohlke & acter, the fusion of hypurals 1-2 with hy-
Robins (1968:47) began their study of New purals 3-4 and the urostyle, but he did not
World seven-spined gobies, which remains provide a list of genera in that group. Bird-
the most comprehensive treatment of the song stated only that he found this character
group. They included 17 genera in their key state in four subgenera of Gobiosoma as
(Bohlke & Robins 1968:51): Psilotris, Var- well as in nine genera presumably derived
icus, Chriolepis, Gobulus, Nes, Pycnomma, from Gobiosoma. He further noted that Mi-
Gymneleotris, Eleotricus, Risor, Parrella, crogobius, Bollmannia, Parrella, and Pal-
Barbulifer, Enypnias, Bollmannia, Aruma, atogobius do not show this fused caudal
Microgobius, Ginsburgellus, and Gobioso- condition and thus are excluded from the
ma. Four other genera were subsumed as Gobiosoma lineage. Birdsong et al. (1988:
subgenera under an expanded concept of 189) treated the "Gobiosoma group" as
Gobiosoma: Austrogobius, Elacatinus, comprising 17 genera: Birdsong's (1975:
Garmannia, and Tigrigobius. Bohlke & 182) Gobiosomatini minus the "Microgo-
Robins (1969) added two more genera, Ev- bius group," and with the questionable ad-
440 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
CHRIOLEPIS
VARIOUS
EVERMANNICHTHYS PSILOTRIS
\
\ PARIAH
GINSB
NELEOTRIS
PYCNOMMA
ELEOTRICA
ARUMA
NES
Fig. 4. Diagram of relationships (from Bohlke & Robins 1969).
dition of Ophiogobius, an eastern Pacific strikingly similar, both having a very large
genus. melanophore on the ventral midline at the
Psilotris is a member of the Gobioso- posterior base ofthe anal fin. Indeed, at first
matini of Birdsong (1975) based on the we did not separate larvae of the two spe-
presence of seven dorsal spines, 11 + 16— cies. It was only after our reared specimens
17 vertebrae, and a dorsal-fin formula of 3- transformed into two distinct species that
221110. It further belongs to the ''Gobio- we reexamined the larvae and recognized
soma group" by virtue of its fused hypural the difference. Larvae of Nes longus have
&
elements. In Bohlke Robins's (1968:51) a second midventral melanophore at the an-
key to genera, Psilotris falls out in the first terior base of the anal fin, in addition to the
couplet along with Varicus, Chriolepis, large one at the posterior end.
Gobidus, and Nes, all characterized by the The most obvious difference between
absence of head pores. Within this group, adults of Nes longus and Psilotris ambly-
the genera are separated by the presence or rhynchus is the form of the pelvic fins.
absence of scales and by the form of the Throughout the ontogeny ofNes, the pelvic
pelvic fins, either united or separate. Bohlke fins of the two sides are completely fused,
& Robins made no claim that their key is and there is a well developed frenum be-
anything more than a convenient way to tween the spines (Fig. 3C, D). In juvenile
identify specimens. Nevertheless, it is in- and adult Psilotris amblyrhynchus the pel-
triguing that four of the five genera are ad- vic fins are almost entirely separate, with
&
jacent on Bohlke Robins's tree (Fig. 4). only a rudimentary membrane between the
The lone outlier is Nes, which arises from bases of the inner rays (Fig. 3B). As dis-
near the base of another branch. Nes, how- tinctive as this character may seem, it is
ever, is of special interest to us, as we have subject to great variation among gobies,
collected larvae of Nes longus and reared even among closely related species. Within
them through transformation. Larvae ofNes the genus Coryphopterus, for example, the
longus and Psilotris amblyrhynchus are pelvic-fin condition spans the complete
VOLUME NUMBER
112, 2 441
Spectrum from fully fused to separate. In the species are not very similar in general
larvae of Psilotris amblyrhynchus, the pel- appearance. Psilotris alepis (the type spe-
vic fins are largely united (Fig. 3A), the in- cies) and P. batrachodes seem most differ-
terradial membrane retreating during trans- ent from P. amblyrhynchus. They are both
formation (Fig. 3B); this suggests that the small, relatively stubby gobies with low fin-
separate pelvic fins are secondarily derived. ray counts. Neither has an elongate dorsal
Although the character is often treated di- spine, and the anterior head profile is dif-
chotomously (united vs. separate) in keys ferent. Psilotris celsus has two elongate
&
such as Bohlke Robins's, the condition dorsal spines rather than one as in P. am-
is not so clear-cut. Gobulus, for instance, is blyrhynchus. This species is also relatively
keyed out by choosing "ventral fin united," stubby, and the eye and mouth are smaller
yet Gobulus has no interspinal frenum, and than those of P. amblyrhynchus. The teeth
the membrane between the inner rays of the of P. alepis, P. batrachodes, and P. celsus
two sides extends no more than a third of are described as being in several to many
the way from the base of the ray to its tip. rows on the jaws, as opposed to the widely
This condition is actually closer to that in spaced, uniserial pattern found in P. am-
Psilotris than in Nes. With only a slightly blyrhynchus. Psilotris kaufmani also has the
greater reduction of the interradial mem- first two dorsal spines elongate (based on
brane in Gobulus, the distinction between it fig. 1 in Greenfield et al. 1993, though it
and Psilotris would disappear. was not mentioned in the text). The color
The other distinctions between Nes lon- pattern of P. kaufmani is quite different
gus and Psilotris amblyrhynchus are the from that of P. amblyrhynchus, it has a
greater elongation of the body with age in much shallower snout profile, it has fewer
Nes and the presence of an extra vertebra second-dorsal-fin elements (10-11 vs. 11-
(28 rather than 27). Resemblances between 12), and it inhabits deeper areas ofreefs and
the two species are the steep anterior profile dropoffs. Psilotris boehlkei lacks elongate
of the head, with its large eye and short dorsal spines (again based on the figure in
snout, and the elongate first dorsal spine in Greenfield, 1993, as the character was not
adults. mentioned in the text), and it has fewer sec-
There is no unique feature that distin- ond dorsal-fin elements (10-11).
guishes Psilotris from the other members of Our assignment of the new species to
the ''Gobiosoma group." It is characterized Psilotris must be considered tentative pend-
only by the combination of three character ing further study of generic concepts among
states: no scales, no head pores, and sepa- seven-spined gobies. Although larval mor-
rate pelvic fins. Each of these characters phology suggests a possible relationship be-
shows a wide range of conditions. For ex- tween Psilotris amblyrhynchus and Nes lon-
ample, some genera are completely scaled gus, little comparative information is avail-
from head to tail, some are partially scaled, able on larval morphology of other species
some have only two small scales at the base of the ''Gobiosoma group."
of the caudal fin, and some have no scales
at all. The number of pores also varies; Acknowledgments
sometimes within a single species certain
pores can be present or absent. The vari- Our studies at Carrie Bow Cay were sup-
ability in pelvic-fin condition has already ported by grants from the Caribbean Coral
been discussed. The trends within the evo- Reef Ecosystems program, K. Ruetzler, di-
lution of these characters cut in different rector M. R. Carpenter, K. C. Cole, and C.
ways across genera. Greenfield (1993:773) E. Thacker assisted in various aspects of
correctly pointed out that Psilotris is not de- our field work. B. Pfeiffer and M. Lara as-
fined by any shared derived characters, and sisted us in rearing larvae. Finally, we wish
442 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
&
to thank G. D. Johnson for his support and 1969. Western Atlantic sponge-
encouragement of our work at Carrie Bow dwelling gobies of the genus Evermannich—thys:
their taxonomy, habits and relationships. Pro-
Cay. This is Contribution No. 561 from the
ceedings of the Academy of Natural Sciences
Caribbean Coral Reef Ecosystems program.
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