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The Eastern Pacific species of Bathygobius (Perciformes : Gobiidae)

August 2001
Revista de Biologia Tropical 49 Suppl 1(1):141-56

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PubMed

Authors:

Stazione Zoologica Anton Dohrn

The circumtropical gobiid genus Bathygobius Bleeker is defined and three Eastern Pacific species are redescribed, with first dorsal fin pattern and postorbital blotches being shown to be additional characters of diagnostic value. Two mainland species are recognised, the Mexican-Panamanian B. ramosus Ginsburg 1947 and the Panamanian B. andrei (Sauvage 1880). B. ramosus is now reported from Clarión Island, Revillagigedos, and also from Cocos Island. Meristic variation of ramosus is tabulated for local populations and PCA analysis of their morphometry suggests regional differentiation in this species, with Tres Marias and Revillagigedos populations clustering away from mainland and Montuosa material. An insular species, B. lineatus (Jenyns 1842) from the Galapagos is defined, with B. arundelii (Garman 1899) from Clipperton Island and B. l. lupinus Ginsburg 1947 from Lobos de Afuera, off Peru, placed as nominal subspecies of lineatus. This species resembles the Indo-west Pacific B. fuscus and Atlantic basin B. soporator more closely than it does ramosus and andrei and may be the product of transpacific dispersal. A similar origin for B. ramosus is discussed but it seems more likely that both B. ramosus and B. andrei have Caribbean sister species.

Diagrams of free fin-ray branching in uppermost six pectoral rays (1-6) in (A) Bathygobius ramosus, based on male, 70 + 17.5 mm, Montuosa Island, Gulf of Chirique, and (b) B. andrei , based on female, 67 + 18 mm, Guatemala.

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Diagrams of first dorsal fin pattern in (A) Bathygobius ramosus, (B) B. andrei, and (C) B. lineatus.

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Pelvic disc in ventral view of (A) Bathygobius line a t u s, male, 78 + 17.5 mm (LACM 4369-1, part), Marchena Island, Galapagos. (B) B. andrei, 92 + 21 mm, female, Guatemala, and (C) B. ramosus. a, anus; an, anal fin; am, anterior membrane; g, urogenital papilla; ll, lateral lobes of anterior membrane; pd, bowl of pelvic disc.

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Opercular scales (op) and associated structures (sensory papillae and canal pores) in holotype of Gobius arundelii, male, 59 + 18 mm (MCZ 28289), Clipperton Island. Other lettering as Fig. 1.

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Rev. Biol. Trop. 49 Supl. 1: 141-156, 2001

The Eastern Pacific species of B a t h y g o b i u s ( P e rciformes : Gobiidae)

Peter J. Miller & Sergio Stefanni

School of Biological Sciences, The University, Bristol, BS8 1UG, UK. [fax +44 (0) 117 925 7374;

e-mail: Peter.Miller@bristol.ac.uk]

Abstract: The circumtropical gobiid genus Bathygobius Bleeker is defined and three Eastern Pacific species are

redescribed, with first dorsal fin pattern and postorbital blotches being shown to be additional characters of diagnostic

value. Two mainland species are recognised, the Mexican-Panamanian B. ramosus Ginsburg 1947 and the Panamanian B.

andrei (Sauvage 1880). B. ramosus is now reported from Clarión Island, Revillagigedos, and also from Cocos Island.

Meristic variation of ramosus is tabulated for local populations and PCAanalysis of their morphometry suggests regional

differentiation in this species, with Tres Marias and Revillagigedos populations clustering away from mainland and Mon-

tuosa material. An insular species, B. lineatus (Jenyns 1842) from the Galapagos is defined, with B. arundelii (Garman

1899) from Clipperton Island and B. l. lupinus Ginsburg 1947 from Lobos de Afuera, off Peru, placed as nominal sub-

species of lineatus. This species resembles the Indo-west Pacific B. fuscus and Atlantic basin B. soporator more closely

than it does ramosus and andrei and may be the product of transpacific dispersal. A similar origin for B. ramosus is dis-

cussed but it seems more likely that both B. ramosus and B. andrei have Caribbean sister species.

Key words: Eastern Pacific, Gobiidae, Bathygobius, islands, species definition, relationships.

Bathygobius Bleeker 1878 is a circum-

tropical assemblage of gobiid fishes, which,

despite their generic name, are essentially lit-

toral in habitat. In the Indo-West Pacific

region, at least a dozen species are probably

eligible for inclusion in the genus. Those

occurring in Japanese waters have been

described in detail by Akihito & Meguro

(1980) and further summarised by Akihito et

al. (1988) while Hoese (1986) has distin-

guished eight species of Indo-Pacific prove-

nance in the warm-water fauna of southern

Africa. In the Atlantic basin, three forms are

currently listed from tropical West Africa, two

endemics (B. casamancus (Rochebrune) and

B. burtoni (O’Shaughnessy)) and the amphi-

atlantic B. soporator (Valenciennes) (Miller

& Smith 1989). In the western Atlantic, as

well as the last named, there are a further two

species, B. curacao (Metzelaar) and B .

mystacium Ginsburg (Ginsburg 1947, Böhlke

& Chaplin 1968, Rubinoff & Rubinoff 1971).

For the tropical eastern Pacific region

(Briggs 1974), Ginsburg (1947) recognised

four species, two essentially continental

(ramosus Ginsburg and andrei (Sauvage)),

lineatus (Jenyns) at the Galapagos and arun -

delii (Garman) from the remote island of

Clipperton, as well as various subspecies

within the first three. The present work has

rexamined eastern Pacific Bathygobius mate-

rial in the light of Ginsburg’s revision, using

Received: 17-III-2000 Corrected: 23-XI-2000 Accepted: 8-XII-2000

R E V I S TA DE BIOLOGIA T R O P I C A L142

V I origin to tip of longest pelvic ray.

Lateral-line system (Fig. 1). Terminolo-

gy of sensory papillae (free neuromast) series

and rows, and of head canal pores, as Miller

and Smith (1989). Sensory papillae and

pores are minute in Bathygobius. Under low-

power binocular microscope, oblique lighting

from a narrow (1 mm) fibre-optic light guide

is often sufficient to reveal these structures,

but iron tannate staining, differentiating with

1% nitric acid (De Buen 1923), may be nec-

essary in some cases. Counts of papillae are

not given, but numbers shown in Fig. 1 are

approximately as found in the specimen

drawn.

C o l l e c t i o n s. Abbreviations for collec-

tions are those of Leviton et al. (1985).

GENERIC IDENTIFICATION

Bathygobius was introduced by Bleeker

(1878) for the Indo-Pacific G o b i u s

petrophilus Bleeker and G. nebulopunctatus

Valenciennes in a species-list without desig-

nation of type-species or diagnosis of the

genus. According to Koumans (1931), Meek

& Hildebrand (1928) designated G. nebulop -

unctatus as the type-species, a form now syn-

onymised with G. fuscus Rüppell (Akihito &

Meguro 1980). Mapo Smitt (type-species

Gobius soporator Valenciennes) and Chlamy -

des Jenkins (type-species Ch. laticeps Jenkins

= G. cotticeps Steindachner) have long been

incorporated into B a t h y g o b i u s (Meek &

Hildebrand 1928, Akihito & Meguro 1980),

as have, more recently, the monotypic west-

ern Indian Ocean Pyosices (type-species P.

niger Smith) and Koumansiasis (type-species

K. macrocephalus Rao) (Hoese & Winterbot-

tom 1979).

Bathygobius is a circumtropical gobioid

genus characterised by the goby-grade fea-

tures of a fused pelvic disc and in the skeleton

by (i) five branchiostegal rays, (ii) endoptery-

goid absent; (iii) urohyal lacking lateral

ridges; (iv) pectoral girdle with hypercora-

coid (scapula) reduced, deeply notched from

below; (v) hypocoracoid (coracoid) small,

additional criteria (Akihito & Meguro 1980,

Miller & Smith 1989, and present observa-

tion) to the essentially meristic and morpho-

metric ones employed by that author. In par-

ticular, the systematic status of Bathygobius

from the eastern Pacific islands has been

addressed. The work is based on study of

available type-material in conjunction with

collections from the Los Angeles County

Museum and new material from Clipperton

Island.

METHODS AND ABBREVIATIONS

Meristics. A, anal fin; C, caudal fin; D1,

D2, first and second dorsal fins; LL, scales in

lateral series (from axilla along lateral mid-

line, excluding scales over origin of C if pre-

sent); P, pectoral fin; Pd, predorsal scales (Pd

along dorsal midline forwards from origin of

D1); Tr, scales in transverse series (from ori-

gin of A obliquely upwards and rearwards to

base of D2); V, pelvic disc. Last bifid ray of

D2 and A counted as one.

Morphometrics (Tables 1, 2, 4, 5). Ab,

anal fin base; Ad and Aw, body depth and

width at anal fin origin; Cl, caudal fin length;

Chd, cheek depth (lower border of eye to

level of angle of jaws); Cp and Cpd, caudal

peduncle length (end of A base to origin of C)

and depth (minimum); D1b and D2b, first and

second dorsal fin bases; E, eye diameter;

E/Pdsc(length of postorbital unscaled nape

along oculoscapular groove); H, Hw, Hd,

head length (snout to midline opposite upper

origin of opercle), width (between upper ori-

gin of opercles), depth (at latter position); I,

interorbital width; Pl, pectoral fin length; Po,

postorbital length; Sl, standard length; Sn,

snout length; Sn/A and Sn/An, distance from

snout to vertical of anal fin origin and anus;

Sn/D1 and Sn/D2, distance from snout to ori-

gin of first and second dorsal fins; Sn/V, dis-

tance from snout to vertical of pelvic spinous

ray origin; Ujl, upper jaw length (midline to

lateral end); V/An, distance from origin of

pelvic spinous ray (V I) to opposite anus; Vd,

body depth at origin of V I; Vl, distance from

I N T E R N AT I O N A L J O U R N A L OF T R O P I C A L B I O L O G Y AND CONSERVAT I O N 143

Fig. 1. Head lateral-line sensory papillae and canal pores (Greek letters) of Bathygobius ramosus, male, 61 + 15 mm

(LACM 30108-9, part), Guancastre Province, Costa Rica, in (A) lateral and (B) dorsal views, and (C) mental region

(enlarged). AN, PN, anterior and posterior nostrils; D, “deltoid” configuration of infraorbital row c; UL, LL, upper and

lower lips; MF, mental fold; other abbreviations as Miller & Smith (1989).

R E V I S TA DE BIOLOGIA T R O P I C A L144

d; (ii) lower cheek groove housing anterior

section of row c, which is joined caudad by

row cp; (iii) trapeziform transverse mental

flap, bordered posteriorly by transverse row f;

and (iv) branched free upper pectoral rays; (v)

10 + 17 vertebrae (Akihito & Meguro 1980,

Miller & Smith 1989).

Bathygobius has most affinity with the

exclusively Indo-West Pacific I s t i g o b i u s

(type-species Gobius ornatus Rüppell 1830)

in the symplesiomorphy of a shortened

hyomandibular row b. The two genera both

possess free pectoral rays, at least in the type

species of Istigobius (Murdy & Hoese 1985),

and the latter shows incipient cheek grooving.

The osteology of Bathygobius and Istigobius

is also similar (Peters 1983, Murdy 1985,

Miller & Smith 1989). However, Istigobius

differs from Bathygobius in (i) larger head

scales; (ii) more convex snout profile; (iii) a

merely bulb-like mental protuberance, and

(v) only 10 + 16 vertebrae (Murdy & Hoese

1985).

The Eastern Pacific species examined in

the present work all possess the diagnostic

features of Bathygobius noted above, and

have the following features in common: (i)

cheek naked; (ii) anterior nasal opening short,

erect, tubular, without a short process from

rear rim; and (iii) lower jaw with inner row of

about 4-5 enlarged lateral caniniform teeth.

The head lateral-line system (as illustrated in

Fig. 1 for B. ramosus) has (i) anterior and

posterior oculoscapular canals separate, and

(ii) interorbital part of anterior oculoscapular

canal with well separated single pores lamb-

da and kappa, all canal pores being very

small. Meristic characters include an almost

invariable count of second dorsal rays I/9 and

anal rays A I/8 (Table 3 and text). Coloration

is variable, with three oblique dark bands

across body and more or less evident longitu-

dinal pale striae corresponding to the focal

axis of scales; head with dark oculoscapular

blotches and a scapular blotch at the upper

origin of the pectoral fin.

opposite lower corner of fourth radial (Miller

& Smith 1989). Among goby-grade gobioids,

Bathygobius belongs in an extensive group of

Old World genera (including Amoya Herre,

Arenigobius Whitley, Cabillus Smith, Cryto -

c e n t ro i d e s Popta, G o b i o p s i s S t e i n d a c h n e r,

I s t i g o b i u s W h i t l e y, P a r k r a e m e r i a W h i t l e y,

Porogobius Bleeker and Silhouettea Smith)

with (i) longitudinal infraorbital papillae

rows a and c, former around eye, and neither

with transverse proliferation; (ii) delta config-

uration of papillae at anterior end of row c;

(iii) well developed ancillary infraorbital row

cp; (iv) transverse rows r and s

, (v) a longi-

tudinal row s;(vi) row f a single transverse

row behind rear edge of mental flap; (vii) lon-

gitudinal row n; (viii) single anterior interor-

bital pore lambda; (ix) pore beta present; and

in skeleton (x) first dorsal fin pterygiophore

sequence of 22110, (xi) one epural; (xii) post-

maxillary crest on premaxilla; and (xiii) fan-

shaped glossohyal (Miller & Smith 1989,

McKay & Miller 1997).

Bathygobius itself may be characterised

by the combination of (i) lateral preorbital

protuberance enclosed by papillae rows c and

Fig. 2. Diagrams of free fin-ray branching in uppermost

six pectoral rays (1-6) in (A) Bathygobius ramosus, based

on male, 70 + 17.5 mm, Montuosa Island, Gulf of

Chirique, and (b) B. andrei, based on female, 67 + 18

mm, Guatemala.

145

to 38.5 + 10.5, and four unsexed, 21.5 + 6 to 35 + 10 mm

(LACM 33546-2), ENE Cape Henslow, Socorro Island,

Revillagigedos Islands, 15 ii 1971, RV Searcher; ten

males, 28 + 7.5 to 47.5 + 13.5, twelve females, 28 + 7.5

to 67 + 19 , and one juvenile, 20.5 + 6 mm (LACM

22697), Sulphur Bay, Clarión Island, Revillagigedos

Islands, 17 iii 1939. ELSALVADOR: seven males, 44 +

11.5 to 80 + 23, and four females, 35 + 9 to 51 + 14 mm

(GCRL), C. E. Dawson. COSTA RICA: three males, 48

+ 13 to 61.5 + 16, and nine females, 30 + 9 to 47 + 12.5

mm (LACM 30108-9), Playa de Tamarinda de Nicoya,

Guancaste prov., 21 i 1964; four males, 42 + 12 to 52.5 +

15.5 mm (LACM 6569-4), Pital, 2 mi S Ta r c o l e s ,

Puntarenas, 29 xii 1962, W. Bussing and A. Obando;

eight males, 28.5 + 8 to 46 + 12, six females, 29 + 8 to

52 + 13.5, and eight juveniles, 10.2 + 2.8 to 22 + 6 mm

(LACM 6894-32), Playa del Coco, 13 vii 1964; five

males, 32 + 8 to 57 + 17, and eight females, 25.5 + 7 to

44.5 + 11.5 mm (LACM 32257), and one male, 35 + 9.5

mm (CAS 206080), (5 33 20N, 87 02 50W); one male, 34

+ 9, and three females, 21.5 + 5.5 to 38.5 + 10 mm

(LACM), Chatham Bay, Cocos Island 28 xii 1998, J. E.

McCosker. PANAMA: 23 males, 34.5 + 8 to 74.5 + 20.5,

and five females, 35 + 9 to 41.5 + 9.5 mm, Montuosa

Island, Gulf of Chiriqui, 12 xii 1998, C. R. Robertson;

ECUADOR: one male, 37 + 10, and six females, 34 + 9.5

to 63 + 16 mm (LACM 33906-11), Guayas, 37 mi N

Santa Elena, 21 v 1970, J. De Weese. PERU: two males,

49.5 + 13 and 81 + 21.5 mm (LACM 33907-6), Piura, 2

mi S Mancora, 37 mi NNW Paita; three males, 45 + 12

to 58 + d, and six females, 41 + d to 48.5 + 14 mm

(USNM 143028, paratypes of B. r. micromma), Paita.

Description. Pectoral rays 19-20 (18-21:

see Table 3 for meristic values); uppermost

BATHYGOBIUS RAMOSUS GINSBURG

1947

Bathygobius ramosus G i n s b u rg 1947: 281

(= B. ramosus

Ginsburg 1947: 281)(Balboa, Panama);

Allen & Robertson 1994: 259; Hoese, in Fischer et al.

1995: 1134.

Bathygobius ramosus ramosus G i n s b u rg 1947

(= B. ramosus

Ginsburg 1947): 282.

Bathygobius ramosus micromma Ginsburg 1947

(=B. micromma

Ginsburg 1947): 282 (Paita, Peru).

Bathygobius ramosus longipinnis Ginsburg 1947

(=B. longipinnis

Ginsburg, 1947): 282 (Socorro Island,

Revillagigedos Islands, Mexico).

Material. MEXICO: 10 males, 30 + 8 to 65 + 18,

and 18 females, 31 + 7.5 to 75 + 20 mm, Agua Verde Bay,

Gulf of California, LACM 20135; three males, 39 + 10 to

51 + 14, four females, 25.5 + 7 to 58 + 15, and two juve-

niles, 22 + 6 and 27 + 7 mm, Chileno Bay, N. of Cabo

San Luca, Gulf of California (LACM 31784-14), 19-20 ii

1971, RV Searcher #59; one female, 31.5 + d mm

(USNM 002474, paratype of B. r. curticeps), Baja Cali-

fornia; one female, 55.0 + d mm (USNM 002327,

paratype of B. r. curticeps), Baja California; three males,

21 + 6.5 to 45 + 13, one female, 54 + 15, and five juve-

niles, 19 + 5.5 to 21.5 + d mm, Guerrero, 1.5 mi SE

Papanoa (17 20 N, 101 01 W), LACM 9044-41; five

males, 46 + 12 to 82 + 24.5, and three females, 51 + 15

to 60.5 + 16 mm, Isabella Island, Sinaloa (LACM 20132,

as soporator), 2 iv 1937, Velero III; eight males, 40 + 11

to 77 + 22.5, and six females, 40 + 10.5 to 48 + 14 mm

(LACM 22194), Tres Marias Island, Magdalena Islands;

eleven males, 25 + d to 60 + 16.5, four females, 28.5 + 8

Key to Eastern Pacific species of

Bathygobius

1a. Pectoral free rays, typically the first and invariably the remaining four, branched at least twice (Fig 2A); first dor-

sal fin distinctly pigmented to distal edge (Fig. 3A); postorbital dark blotches on oculoscapular groove large, elon-

gate medially (Fig 4C); pelvic disc more or less rounded, with large lateral lobes, sometimes attenuate, and disc

length about two-thirds to four-fifths abdomen (Fig. 5C); pectoral rays 19-20 (18-21); scales in lateral series 34-36

(32-38). Baja California to Peru, Revillagigedos and Cocos Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ramosus

1b. Pectoral free rays only bifid (Fig. 2B); first dorsal with at least distal periphery pale (Fig. 3B,C); postorbital dark

blotches on oculoscapular groove small, not produced medially (Fig. 4A,B); pelvic disc usually more or less ellip-

tical, sometimes circular, lateral lobes not attenuate and disc length at least four-fifths abdomen . . . . . . . . . . . .2.

2a. First dorsal fin with oblique dark band, most intense at upper anterior and lower posterior areas of fin (Fig. 3B);

opercle typically with small patch of scales in upper anterior corner; pelvic disc not reaching anus, lateral lobes vari-

able (Fig. 5B); pectoral rays 21-22 (20-22); scales in lateral series 34-36 (33-36); Guatemala to Ecuador . .andrei

2b. First dorsal fin with horizontal markings, proximal dark lines more intense posteriorly, and an upper clear distal edge

(Fig. 3C); opercle typically without scales (present or absent in Clipperton examples (Fig. 6); pelvic disc (Fig. 5A)

with small lateral lobes, edge of disc often reaching anus; pectoral rays 19-21; scales in lateral series 30-37; Gala-

pagos (lineatus), Clipperton Island (arundelii) and Lobos de Afuera, Peru (lupinus) . . . . . . . . . . . . . . . . .lineatus

I N T E R N AT I O N A L J O U R N A L OF T R O P I C A L B I O L O G Y AND CONSERVAT I O N

R E V I S TA DE BIOLOGIA T R O P I C A L146

length 8.8-11.4 (see Tables 1 and 2 for

descriptive morphometric values); posterior

tip of second dorsal extending to above cau-

dal fin base in males, to upper origin of cau-

dal in females. Coloration with large dark

postorbital blotches, extending medially from

oculoscapular furrow and larger in area then

pupil; scapular blotch dark; lateral midline

with blotches not markedly extending below

lateral midline; first dorsal fin more or less

dusky to distal edge, lacking pale band, and

with more proximal dark longitudinal band

indistinct except as darkening on rear interra-

dial membranes; caudal fin with distinct ver-

tical markings; head with small white ocelli

variably evident on lower cheek and opercle.

Distribution. As Ginsburg (1947) noted,

this species appears to be “the commonest

and most widespread species of Bathygobius

on the Pacific coast of the American conti-

nents” and ranges from southern Baja Cali-

fornia to Peru (Ginsburg 1947, Thomson et

a l . 1979). This extensive distribution

embraces both the Mexican and Panamanian

provinces of the Eastern Pacific region (Brig-

gs 1974). Bathygobius ramosus also occurs at

both nearshore islands (such as the Tr e s

Marias, Mexico and Montuosa Island in the

Gulf of Chirique) as well as at the more off-

shore Revillagigedos (Ginsburg 1947, Ricker

1959), including the most distant Clarión

Island, and also Cocos Island (5

3 3 ’ N ,

8 6

59’W) (present material). B a t h y g o b i u s

reported from Malpelo Island off Colombia

have not been available for study but may be

predicted to be this species. Habitat. Report-

ed from intertidal rock-pools (Allen &

Robertson 1994). Maximum size to 11.4 cm

(Thomson et al. 1979): the largest male in the

present material is 82 + 24.5 = 106.5 mm TL

and the largest female 75 + 20 = 95 mm TL,

both from northern localities (Isabella Island,

Tres Marias, and Gulf of California, respec-

tively).

Local variation. Ginsburg (1947) distin-

guished four subspecies of ramosus - ramo -

sus, curticeps, micromma and longipinnis -

on the basis of head length, caudal fin, pos-

six rays more or less free from membrane

(Fig. 2A), first usually branched twice, some-

times merely bifid, second ray branched

twice, third and fourth three times, fifth four

times, and sixth five times; secondary and

subsequent branching evident by standard

length of 18 mm. Pelvic disc circular or

somewhat elliptical, about two thirds to four

fifths length of abdomen (pelvic origin to

anus); anterior pelvic membrane with lateral

edges typically produced, angular to attenu-

ate, each up to half length of free edge of

membrane, which may be convex medially in

outline. Scales in lateral series 34-36 (32-38;

see Table 3); opercle without scales; predor-

sal scales (mostly 16-20) extending anteriorly

to at least opposite pore beta, with distance

thence to edge of orbit 2.7-3.9% SL; breast

two-thirds to fully scaled. As %SL, caudal fin

24.2-29.6, pectoral fin length 19.3-26.6,

pelvic disc length 16.2-21.1, caudal peduncle

depth 11.5-13.8, eye 5.5-9.0, upper jaw

Fig. 3. Diagrams of first dorsal fin pattern in (A) Bathy -

gobius ramosus, (B) B. andrei, and (C) B. lineatus.

147

analysis of this species. However, compari-

son of available measurements for the body

proportions noted above (Tables 1, 2) for the

Gulf of California, Tres Marias islands and

Gulf of Chiriqui suggest significant differ-

ence between beween males from Chiriqui

and the other localities in upper jaw propor-

tion, and between males of Tres Marias and

the other localities in postorbital percentage

of standard length. Principal components

analysis (Fig. 7) of available body measure-

ments (excluding upper jaw length and head

depth) indicate some regional differentiation

in ramosus. There is some overlap, but the

Tres Marias and Revillagigedos individuals

cluster apart from mainland and Montuosa

material, where Gulf of California, Costa

Rican and Montuosa values form a sequence

reflecting their latitudinal distribution. Meris-

tic results (Table 3) also correspond with

Ginsburg’s findings that the Revillagigedos

populations, from both Socorro and the more

distant Clarión Island, show more frequent

occurrence of lower pectoral fin-ray counts,

with the lowest value of 18 also found in the

Tres Marias sample, much nearer the main-

land. Geographical variation obviously

requires study at the genetic as well as classi-

cal morphological level and Ginsburg ’s

delimitation of subspecies and present results

could provide a starting point for such inves-

tigation. At present, there would seem most

justification for formal use of the subspecific

name longipinnis for the Revillagigedos and

the Tres Marias populations on the basis of

pectoral counts and morphometry but there is

no morphological case for elevating them to

separate specific rank. Allen & Robertson

(1994) regarded B. arundelii from Clipperton

Island as a synonym of B. ramosus but this is

not the case (see B. lineatus).

BATHYGOBIUS ANDREI (SAUVAGE

1880)

Gobius andrei Sauvage 1880: 44 (Rio Guayas,

Ecuador).

Bathygobius andrei G i n s b u rg 1947: 282

(= B. andrei

Ginsburg, 1947: 282), Allen & Robertson

1994: 258; Hoese, in Fischer et al. 1995: 1134.

torbital length, eye, nape and upper jaw, later-

al scale and pectoral ray counts, and extent of

branching of the free pectoral rays. B. r.

longipinnis was represented by samples from

Mexico and northern South A m e r i c a

(Ecuador and Colombia), B. r. ramosus from

Panama, B. r. micromma from Peru and B. r.

longipinnis from Socorro island in the Revil-

lagigedos. In the present work, limited mate-

rial does not permit a detailed morphometric

Fig. 4. Diagrams of postorbital blotches (pb) in (A B. lin -

eatus, male, 45 + 11.5 mm (LACM 43689-1, part),

Marchena Island, Galapagos; (B) B. andrei, male, 56.5 +

13 mm (USNM 081934, part), and (C) Bathygobius

ramosus, male, 62 + 17 mm, Montuosa Island, Gulf of

Chirique.

I N T E R N AT I O N A L J O U R N A L OF T R O P I C A L B I O L O G Y AND CONSERVAT I O N

R E V I S TA DE BIOLOGIA T R O P I C A L148

and 117 + 31 mm (NMW 30812-3). COLUMBIA: one

male, 39.5 + 10 mm (LACM 21976), Gorgonia Island, 24

ii 1938, Velero III.

Description. Pectoral rays 21-22 (20:1,

21:24, 22:9); uppermost six rays more or less

free from membrane, first to fourth branched

only once (Fig. 2B). Pelvic disc (Fig. 5B) cir-

cular to somewhat elliptical, four fifths to

nine-tenths length of abdomen; anterior

pelvic membrane with lateral edges more or

less angular, up to half length of free edge of

membrane but typically less pronounced, and

latter without median convexity in outline.

Scales in lateral series 34-36 (33-36; 33:1,

34:10, 35:4, 36:7); opercle with a varying tri-

angular patch of small scales in upper anteri-

or corner, sometimes absent; predorsal scales

19-25, extending anteriorly to at least oppo-

site pore beta, with distance thence to edge of

orbit 1.6-4.8% SL; breast scaled. As %SL,

caudal fin 18.4-30, pectoral fin 16.8-25.1,

pelvic disc length 18-22.6, caudal peduncle

depth 11.8-16.8, eye 6.1-9.6, upper jaw

length 9.2-12.3 (see Table 4 for descriptive

morphometric values); posterior tip of second

dorsal extending to upper origin of caudal fin

in males, not reaching upper origin of caudal

in females. Coloration as Allen & Robertson

(1994); postorbital blotches small, not

extending medially; scapular blotch dark; lat-

eral midline with blotches not markedly

extending below lateral midline; first dorsal

fin with oblique dark band, most intense on

distal part of I/II and II/III membrane and

around origins of IV-VI, and upper posterior

area of fin pale; second dorsal and anal fin

dark, with pale rim; caudal fin dark but mark-

ings indistinct in larger fish; head usually

without pale ocelli.

D i s t r i b u t i o n. A seemingly mainland

species, recorded from Guatemala (Esquitla)

to Ecuador (Guayaquil) (Ginsburg 1947,

Allen & Robertson 1994, present material),

and thus apparently restricted to the Pana-

manian province of Briggs (1974). So far,

this goby has not been reported from those

offshore islands where B. ramosus is found.

Bathygobius andrei andrei Ginsburg 1947: 283

(= B. andrei

Ginsburg 1947: 283).

Bathygobius andrei heteropoma Ginsburg 1947:

283 (= B. heteropoma

Ginsburg 1947: 283) (Chame

Point, Panama).

Bathygobius andraei Eschmeyer 1998: 98

[Eschmeyer (1998) states that andraei is the original

spelling of this name but reference to Sauvage’s text indi-

cates andrei].

Material. GUATEMALA: Five males, 45 + 13.5

to 118 + 35 mm, and six females, 54 + 14.5 to 89 + 25

mm (GCRL 1451,1458,1461,1463,1469), Esquintla,

1984, C. E. Dawson. PANAMA: two males, 62 + 16 and

96 + 17.7 (USNM 082207, paratypes of Bathygobius

andrei heteropoma), Chame Point, Tweedie; two males,

47 + 12 and 75 + 16, and two females, 56.5 +13 and 60.5

+ 14.5 mm (USNM 081934, paratypes of Bathygobius

andrei heteropoma), Chame Point, Tweedie; two, 90 + 22

Fig. 5. Pelvic disc in ventral view of (A) Bathygobius lin -

e a t u s, male, 78 + 17.5 mm (LACM 4369-1, part),

Marchena Island, Galapagos. (B) B. andrei, 92 + 21 mm,

female, Guatemala, and (C) B. ramosus. a, anus; an, anal

fin; am, anterior membrane; g, urogenital papilla; ll, lat-

eral lobes of anterior membrane; pd, bowl of pelvic disc.

149

29 and 20-23 for the two forms respectively.

It is also evident that male heteropoma have

shorter caudal fins and probably pelvic discs

(Table 4). However all the material examined

here displays a similar pattern of first dorsal

fin pigmentation, as far as can be judged after

preservation, and the subspecific status

assigned by Ginsburg could be retained.

There is obviously a need for ecological

investigation of this morphological species.

The specimen from Colombia has no opercu-

lar scales, an extreme of variation noted by

Ginsburg, but was identified here as andrei

by first dorsal coloration.

BATHYGOBIUS LINEATUS (JENYNS

1842)

Gobius lineatus Jenyns 1842: 95, pl. 19 (fig. 2,2a)

(off San Cristóbal [Chatham] Island).

Gobius arundelii Garman 1899: 63 (Clipperton

Island, Eastern Pacific)

Bathygobius arundelii (Garman): Ginsburg 1947,

Allen & Robertson 1984: 259, Hoese, in Fischer at al.

1995: 1134.

Bathygobius lineatus lineatus (Jenyns) (= Bathy -

gobius lineatus

(Jenyns)): Ginsburg 1947: 281, 284.

Bathygobius lineatus lupinus (=Bathygobius lupi -

nus

) Ginsburg 1947: 281, 284.

Bathygobius lineatus (Jenyns): Allen & Robertson

1994: 259, Hoese, in Fischer et al. 1995: 1134; Grove &

Lavenberg, 1997: 552, 675, 695.

Material. ECUADOR: San Cristobal [Chatham]

Island, Galapagos: one female, 97 + 23 mm, (BMNH

1917.7.14.53, holotype of Gobius lineatus); Marchena

[Bindloe] Island, Galpagos: sixteen males, 33.5 + 8.5 to

78 + 19 mm, and fifteen females, 29 + 7.5 to 56 + 14 mm

(LACM 43689-1), SW side, tide-pool, 18 v 1984, coll.

GAL84-32. Isabela [Albemarle] Island, Galapagos, three

females, 23 + d to 38.5 + 10 mm and two juveniles, 18 +

5 and 18 + d mm (LACM 21969), 22 I 1938. PERU: two

males, 53 + 13.5 and 68 + 18 mm (USNM 077561,

paratypes of B. l. lupinus), Lobos de Afuera Island.

CLIPPERTON ISLAND: one male, 59 + 18 mm (MCZ

28289, holotype of Gobius arundelii), J. Arundel, 1898;

seven males, 35 + 10.5 to 65 + 20 mm, and three females,

38 + 10 to 45 + 11.5 mm (USNM 334096); two males, 43

+ d and 57 + 16.5 mm, 30 iv 1998, R. Robertson.

Description. Pectoral rays 19-21 (19:18,

20:49, 21:18); uppermost five rays more or

less free from membrane (as Fig. 2B), first to

fourth branching only once. Pelvic disc (Fig.

5A) elliptical, reaching at least four-fifths to

Habitat. The type was collected from

brackish water (Sauvage 1880), and the

species is also reported from both tidepools

and sublittoral areas (Ginsburg 1947). A male

of 118 + 35 mm among the present material

from Guatemala exceeds the maximum size

of about 10 cm suggested by Allen & Robert-

son (1994).

Local variation. Ginsburg (1947)

believed that this species could be divided

into two sympatric subspecies, the typical

form from intertidal habitats and B. a. het -

eropoma which was regarded as probably

derived from deeper water, given the methods

used by Robert Tweedlie, who collected the

type series (Meek & Hildebrand 1923). The

subspecies were distinguished by relative

abundance of opercular scales and by length

of pectoral fin. In the present material, oper-

cular scales have been noted but condition of

the specimens has not permitted precise

counting. However, pectoral fin measure-

ments, as percentages of standard length,

agree closely with Ginsburg’s findings, being

22.1-25.1 (males) and 22.8-24.8 (females) for

andreiother than heteopoma syntypes, whose

pectoral fins are 16.8-21.9 (males) and 19.6

and 23.5 (two females), Ginsburg citing 22-

Fig. 6. Opercular scales (op) and associated structures

(sensory papillae and canal pores) in holotype of Gobius

arundelii, male, 59 + 18 mm (MCZ 28289), Clipperton

Island. Other lettering as Fig. 1.

I N T E R N AT I O N A L J O U R N A L OF T R O P I C A L B I O L O G Y AND CONSERVAT I O N

R E V I S TA DE BIOLOGIA T R O P I C A L150

part of fin pale; second dorsal fin with dark

and pale bands; anal fin dusky, with with dark

line proximal to white distal edge; caudal fin

with dark markings more or less defined.

Distribution. An insular form, not only

from the Galapagos province of the Eastern

Pacific region (Briggs 1974) but also from

Clipperton Island, an isolated atoll at

10°18’N, 109°13’W, and Lobos de Afuera

(6°57’S, 80°43’W), small islands about 40 mi

off northern Peru (Ginsburg 1947, Allen &

Robertson 1994). At the Galpagos, the

species is recorded throughout the archipel-

ago (at Baltra, Bartolomé, Fernandina, Flore-

ana, Gardner, Isabela, Marchena, Santa Cruz,

Santiago, San Cristóbal, Tower and Wolf)

(Grove & Lavenberg 1997) Habitat. Collect-

ed from intertidal rock-pools (Allen &

Robertson 1994), where the species is said to

dominate the shallow tidepool habitat (Grove

& Lavenberg, 1997).

Local variation. If coloration of the first

dorsal fin (Fig. 3) is used as the prime char-

acter for distinguishing morphological

species and putatively of biological signifi-

cance, rather than morphometric and meristic

values, and the apparently variable opercular

scales, then the eastern Pacific Bathygobius

fall clearly into three forms - ramosus, andrei

and l i n e a t u s . Within l i n e a t u s, Garman’s

species a ru n d e l i i from Clipperton Island,

maintained as such by Ginsburg (1947), must

be regarded as a morphological subspecies of

lineatus because the first dorsal pattern agrees

with that of the Galapagos lineatus. The

Bathygobius material now examined from

Clipperton Island includes the holotype,

which has opercular scales (Ginsburg 1947,

and shown here in Fig. 6), and a more recent

collection of fish among which no opercular

scales could be detected. In other respects,

these individuals closely resemble the holo-

type. Most display an iridescent blue scapular

blotch which is not evident in the latter which

has been about a century longer in preserva-

tive. The Clipperton Island specimens differ

in number of scales in lateral series (30-34;

30:2, 31:3, 32:2, 33:3, 34:1) from the Galapa-

entire distance to anus; anterior pelvic mem-

brane with lateral lobes one seventh to two-

fifths width of free edge, which is concave in

outline. Scales in lateral series 30-37 (see

Local Variation); opercle with or without a

patch of small scales in upper anterior corner;

predorsal scales 18-21, extending anteriorly

to between pores beta and alpha, with dis-

tance thence to edge of orbit 2.0-3.58% SL;

breast scaled. As %SL, caudal fin 22.2-27.9,

pectoral fin 22.6-26.3, pelvic disc length 20-

22.8, caudal peduncle depth 11.8-14.0, eye

6.6-8.9, upper jaw length 8.17-10.3 (see Table

5 for descriptive morphometric values); pos-

terior tip of second dorsal not extending

beyond upper origin of caudal fin. Coloration

as Allen & Robertson (1994) and Grove &

Lavenberg (1997); postorbital dark blotches

small, not extending medially; scapular

blotch prominent, more or less bluish; head

with numerous small white ocelli on lower

cheek and opercle; first dorsal fin with proxi-

mal pale band at base, two longitudinal dark

lines, lower and wider more intense on V/VI

membrane and postdorsal membrane; upper

Fig. 7. Plot of scores for factors 2 and 5 from principal

components analysis of body proportions in six samples

of Bathygobius ramosus, from localities indicated by

symbols. Measurements as described in Methods and

Abbreviations. Solid line encloses specimens from Tres

Marias Islands and Revillagigedos, broken line those

from mainland and Gulf of Chirique (Montuosa Island)

localities.

151

Clipperton Island population, whose apparent

variablity in opercular squamation may indi-

cate a more complex systematic situation. In

the meantime, the three taxa may be regarded

as conspecific morphological subspecies.

AFFINITIES

Using lateral-line criteria, the genus

Bathygobius can be subdivided into three

groups : (i) an Indo-West Pacific line of

cyclopterus, niger and cotticeps, with contin-

uous oculoscapular canals above the preoper-

cle, and the horizontal hyomandibular row d

separate from its anterior supralabial part.

These species also show the distinctive

gos and Lobos de Afuera material, which has

34-37 (34:3, 35:10, 36: 12, 37: 7). Ginsburg

(1947) distinguished the Lobos de Afuera lin -

eatus as a separate subspecies - lupinus - on

the basis of caudal peduncle depth, percent-

ages of standard length being 11.5-14.5 for

Galapagos lineatus and 14.5-15.5 for lupinus.

Present measurements for males indicate

12.5-14.0 for the former, and 13.2 and 14.4

for the two male paratypes of lupinus. Other-

wise the two localities correspond exactly in

meristic and other morphometric values. It is

apparent that the Galapagos and Lobos de

Afuera populations are much closer in mor-

phology to each other than they are to the

TABLE 1

Body proportions of male Bathygobius ramosus, from Agua Verde Bay (Gulf of California), Tres Marias Islands and

Montuosa Island (Gulf of Chirique), and Clarion Island (Revillagigedos), as percentage of standard length.

Area Agua Verde Tres Marias Montuosa Island Clarion

SL(mm) 41-65 40-77 49.0-74.5 47.5

N 6 8 12 1

H 24.4-27.7 (26.2,1.15) 26.6-29.3 (27.7,0.89) 26.0-30.2 (27.9,1.31) 25.3

Sn/D1 33.6-36.9 (35.0,1.16) 34.9-37.2 (36.5,0.70) 34.2-38.0 (36.0,1.30) 33.7

Sn/D2 53.8-63.8 (56.7,3.76) 55.6-57.9 (56.8,0.85) 54.8-60.4 (57.0,1.55) 54.7

Sn/AN 51.2-53.1 (52.3,0.63) 51.7-57.9 (53.7,2.36) 51.0-56.4 (54.3,1.60) 51.6

Sn/A 56.0-58.5 (57.2,0.96) 57.3-62.3 (59.2,1.64) 56.7-61.7 (59.4,1.56) 54.7

Sn/V 26.3-28.9 (27.8,0.89) 23.0-30.5 (28.8,2.46) 27.9-32.1 (30.3,1.40) 25.7

V/An 23.3-25.3 (24.7,0.72) 22.0-28.6 (24.7,2.50) 22.3-26.0 (23.8,1.25) 24.9

Cp 22.2-24.0 (23.1,0.75) 20.6-26.3 (23.5,1.88) 20.0-22.9 (21.4,0.99) 21.2

D1b 11.9-13.9 (12.5,0.83) 0.8-13.1 (12.1,0.77) 11.5-13.9 (13.0,0.79) 13.1

D2b 23.1-25.0 (23.9,0.96) 19.4-24.8 (22.2,1.74) 22.2-25.7 (23.7,1.10) 22.3

Ab 17.6-18.9 (18.3,0.55) 16.4-19.0 (17.8,1.01) 16.6-20.5 (18.7,1.12) 20.3

Cl 24.2-27.7 (26.1,1.54) 26.3-29.2 (27.6,1.11) 25.8-28.3 (27.1,0.80) 28.4

Pl 21.3-24.1 (22.7,1.11) 21.6-26.1 (23.6,1.37) 19.3-23.3 (21.6,1.28) 23.3

Vl 17.4-20.3 (18.8,1.12) 16.8-18.8 (18.1,0.69) 16.3-19.7 (17.5,0.86) 18.3

Vd 18.1-19.1 (18.7,0.34) 17.2-20.2 (18.4,1.03) 17.3-20.7 (19.3,1.01) 17.9

Ad 16.9-19.1 (18.0,0.78) 16.3-18.2 (17.4,0.61) 15.7-18.3 (17.7,0.71) 17.9

Aw 12.7-14.5 (13.6,0.70) 9.7-11.1 (10.6,0.48) 12.2-14.3 (13.3,0.55) 10.8

Cpd 12.0-13.2 (12.5,0.38) 12.1-13.6 (12.6,0.53) 11.9-13.8 (13.0,0.60) 13.4

Hw 15.3-16.9 (16.2,0.59) 15.4-16.9 (15.9,0.50) 14.7-16.8 (15.9,0.68) 14.0

Hd 15.3-18.9 (18.1,1.37) 16.7-17.5 (17.0,0.37) 17.5-21.0 (19.0,1.01)

Sn 4.4-7.2 (5.8,0.90) 5.1-8.3 (6.3,0.97) 5.4-7.8 (6.7,0.70) 5.0

E 6.5-8.5 (7.4,0.67) 6.8-8.6 (8.0,0.58) 5.5-8.4 (7.4,0.72) 6.8

Po 12.5-13.5 (12.9,0.37) 13.4-14.7 (14.0,0.45) 12.5-14.5 (13.3,0.69) 12.9

Ujl 8.8-10.1 (9.3,0.47) 9.0-10.1 (9.5,0.50) 10.1-11.4 (10.5,0.44)

Chd 6.4-7.7 (6.9,0.48) 5.7-8.2 (6.6,0.84) 5.4-8.4 (7.2,0.77) 5.2

E/Pdsc 2.8-3.5 (3.1,0.32) 3.1-3.9 (3.4,0.36) 2.9-3.9 (3.3,0.40)

I 3.1-4.4 (3.8,0.41) 1.9-3.6 (2.7,0.57) 2.9-6.2 (4.2,0.78) 3.85

%V/An,

V 70.6-81.0 (76.3,3.46) 60.8-82.5 (73.7,7.41) 62.5-79.8 73.7,5.09) 73.6

Values are range, and, in parentheses, mean and standard deviation; N, number of observations.

I N T E R N AT I O N A L J O U R N A L OF T R O P I C A L B I O L O G Y AND CONSERVAT I O N

R E V I S TA DE BIOLOGIA T R O P I C A L152

scales which also characterise the Indo-West

Pacific species (Akihito & Meguro 1980). In

a numerical analysis of Bathygobius species,

Miller & Smith (1989) rooted their most par-

simonious Wagner tree to emphasize an

apparently monophyletic grouping within

B a t h y g o b i u s, comprising the Indo-Pacific

c y c l o p t e ru s, c o t t i c e p s and n i g e r, together

with ramosus. It was then suggested that

ramosus might be derived from common

stock with the former if the Eastern Pacific

barrier had been crossed by such stock after

the closure of the Central American isthmus

(Woodring 1966, Stehli & Webb 1985), or

might represent eastern Pacific survival of an

synapomorphies of a short rounded pelvic

disc with lobate anterior membrane and free

pectoral rays branching more than once; (ii)

the Indo-West Pacific petrophilus with only

one, rather than two, interorbital pores; and

(iii) several species with the more generalised

features of separate anterior and posterior

oculoscapular canals and two interorbital

pores.

All the Atlantic basin and eastern Pacif-

ic species fall into the last category in lateral-

line terms, but ramosus resembles the first

group in extent of branching of free pectoral

rays and in possessing a circular pelvic disc.

However, it lacks the nasal tentacle and head

TABLE 2

Body proportions of female Bathygobius ramosus, from Agua Verde (Gulf of California), Tres Marias Islands (Mexico)

and Clarion Island (Revillagigedos), as percentage of standard length.

Area Agua Verde Tres Marias Clarion

Sl (mm 40-48 45-75 45-67

N 6 6 6

H 26.2-29.3 (27.5,1.13) 26.2-29.3 (27.5,1.13) 26.2-29.3 (27.5,1.13)

Sn/D1 32.7-37.7 (36.0,1.87) 35.5-38.4 (37.1,1.11) 35.1-37.3 (35.8,0.89)

Sn/D2 53.8-57.7 (55.9,1.57) 54.4-61.6 (57.7,2.44) 55.6-58.2 (57.3,1.06)

Sn/An 51.6-58.7 (54.7,2.93) 52.3-57.3 (55.0,1.72) 52.8-55.6 (54.5,1.46)

Sn/A 56.1-63.3 (59.7,2.80) 60.0-63.4 (61.2,1.21) 55.6-60.0 (58.6,1.77)

Sn/V 26.2-30.7 (28.1,1.52) 27.3-32.0 (30.1,1.68) 27.2-30.2 (28.5,1.16)

V/An 25.2-29.3 (27.5,1.78) 22.1-27.5 (24.5,1.82) 24.5-27.1 (25.7,1.11)

Cp 21.6-23.6 (22.6,0.71) 21.4-24.1 (23.1,1.00) 20.3-23.2 (21.5,1.07)

D1b 11.8-12.7 (12.4,0.43) 11.7-13.3 (12.2,0.57) 13.2-13.7 (13.5,0.23)

D2b 21.7-23.4 (22.9,0.63) 20.8-23.4 (21.8,0.981 21.9-23.9 (22.7,0.83)

Ab 16.0-18.3 (17.0,0.81) 15.0-18.5 (16.7,1.27) 18.0-20.0 (19.2,0.74)

Cl 24.2-36.0 (26.7,4.64) 24.8-28.5 (26.9,1.33) 27.0-29.6 (28.0,1.01)

Pl 21.1-23.7 (22.3,0.83) 23.7-25.7 (24.8,0.82) 22.8-26.6 (24.4,1.53)

V 18.1-21.1 (19.4,1.27) 16.2-19.0 (17.3,1.09) 16.5-19.4 (17.8,1.16)

Vd 18.5-20.4 (19.3,0.71) 18.1-20.2 (19.1,0.76) 17.5-19.7 (18.7,0.97)

Ad 16.8-18.5 (17.8,0.56) 16.4-18.6 (17.9,0.82) 17.5-18.1 (17.9,0.29)

Aw 13.1-14.9 (14.5,0.67) 9.6-10.9 (10.3,0.46) 9.8-11.9 (10.8,0.91)

Cpd 11.9-12.7 (12.4,0.28) 11.5-13.0 (12.2,0.62) 12.6-13.6 (13.0,0.36)

Hw 15.9-17.4 (16.6,0.60) 15.4-17.8 (16.6,0.87) 14.8-16.5 (15.6,0.74)

Hd 17.7-20.2 (19.3,0.92) 17.4-17.9 (17.6,0.35) -

Sn 5.2-6.5 (5.9,0.51) 5.2-6.6 (5.9,0.44) 5.4-6.8 (6.1,0.58)

E 7.1-7.8 (7.5,0.33) 8.6-9.0 (8.8,0.21) 7.9-8.6 (8.2,0.29)

Po 12.9-14.3 (13.5,0.54) 13.3-14.7 (14.3,0.59) 12.7-14.1 (13.6,0.57)

Ujl 9.0-9.8 (9.6,0.35) 8.8-10.9 (9.7,1.12)-

Chd 6.3-7.9 (7.2,0.53) 5.7-11.3 (7.0,2.12) 5.9-6.9 (6.4,0.38)

E/Pdsc 2.8-3.8 (3.2,0.37) 2.7-3.0 (2.9,0.20) -

I 3.4-4.7 (4.2,0.46) 2.3-3.7 (2.7,0.52) 2.6-3.5 (3.0,0.4)

%V/An,

V 62.6-83.2 (71.0,7.15) 64.9-76.2 (71.0,3.89) 62.3-74.7 (69.5,4.60)

Values are range, and, in parentheses, mean and standard deviation; N, number of observations.

153

tion for at least 3-5 million years old (Simkin

1984), with shallows since 5-15 mya

(McCosker & Rosenblatt 1984). Alternative-

ly, convergence in extent of pectoral ray

branching and shape of the pelvic disc is seen

in other intertidal gobiids as distant from

Bathygobius, as, for example, some eastern

Atlantic-Mediterranean Gobius and Mauligo -

bius species (Miller 1984, 1986, Brito &

Miller in press). These modifications may be

of adaptive value in the supposedly extreme

intertidal habitat (Horn et al. 1999). The fact

that ramosus does not show the other apo-

morphies, putatively less homoplasious, of

the Indo-West Pacific group may support the

original post-Tethyan circumtropical distribu-

tion, whose Atlantic component became

extinct after the same event. However,

although the putative c y c l o p t e ru s - r a m o s u s

lineage is represented around the Hawaian

archipelago by B. cotticeps (Gosline & Brock

1960), it is not known from the Galapagos,

whose inshore fish fauna is essentially East-

ern Pacific in character, although with Indo-

West Pacific elements (McCosker & Rosen-

blatt 1984), or from other offshore Eastern

Pacific islands, where any ability to cross the

Pacific by this species-group could be most

evident (Greenfield et al. 1970). The Galapa-

gos Islands have been in the appropriate posi-

TABLE 3

Meristic variation in Bathygobius ramosus from Gulf of California to Peru.

D2 8 9 10 N P 18 19 20 21 N

Mv - 25 - 25 Mv - 8 39 1 48

Mb - 7 - 7 Mb - 5 11 - 16

Mm - 14 - 14 Mm 2 13 11 - 36

Mi - 10 - 10 Mi - 6 14 - 20

Rs - 9 1 10 Rs 3 17 - - 20

Rc - 22 1 23 Rc 8 36 2 - 46

Es - 9 - 9 Es - 3 7 - 10

Cc - 27 - 27 Cc - 4 45 3 52

Pm 1 20 - 21 Pm - 13 25 - 38

Ci - 13 1 14 Ci - 3 30 7 40

Pg - 6 1 7 Pg - - 10 2 12

Pp - 2 - 2 Pp - 2 6 - 8

A 7 8 9 N LL 32 33 34 35 36 37 38 N

Mv - 24 - 24 Mv 1 4 12 17 3 1 - 38

Mb - 7 - 7 Mb - 1 6 5 3 - - 15

Mm 1 13 - 14 Mm - - 4 10 7 1 1 23

Mi - 10 - 10 Mi - 1 3 3 1 - - 8

Rs - 9 - 9 Rs - 1 7 6 4 - - 18

Rc - 22 1 23 Rc - 1 4 13 7 1 2 28

Es 1 8 - 9 Es - - 1 5 4 - - 10

Cc - 26 - 26 Cc 1 2 11 11 1 - - 26

Pm 1 20 - 21 Pm 1 2 3 11 2 - - 19

Ci - 14 - 14 Ci - 2 1 9 1 - - 13

Pg - 6 1 7 Pg - - 2 4 1 - - 7

Pp - 2 - 2 Pp - - 5 8 2 - - 15

Counts of second dorsal (D2), anal (A), and pectoral (P) rays, and scales in lateral LL) series, in samples from Agua

Verde Bay, Gulf of California (Mv); Baja California, Mexico (Mb); Magdalena Island, Tres Marias, Mexico (Mm);

Isabella Island, Mexico (Mi); Socorro Island, Revalligigedos (Rs); Clarion Island, Revillagigedos (Rc); El Salvador

(Miller & Smith 1989); (Es), Playa del Coco, Costa Rica (Cc); Cocos Island (Ci); Montuosa Island, Gulf of Chirique

(Pm); Guayas, Ecuador (Pg); Piura and Paita, Peru (Pp); N, number of observations.

I N T E R N AT I O N A L J O U R N A L OF T R O P I C A L B I O L O G Y AND CONSERVAT I O N

R E V I S TA DE BIOLOGIA T R O P I C A L154

The three taxa here grouped under linea -

tus -lineatus from the Galapagos, lineatus

lupinus from Lobos de Afuera and arundelii

from Clipperton - key out to Indo-West Pacif-

ic fuscus or to Atlantic basin soporator, fol-

lowing the characters used by Akihito &

Meguro (1980), Hoese (1986) and Miller &

Smith (1989). The pigmentation of the first

dorsal fin is essentially as in fuscus (Akihito

& Meguro 1980) and soporator (Miller &

Smith 1989). As a complication, arundelii

with opercular scales and also low lateral

scale counts does seem close to the Caribbean

lepidopoma. These populations may be the

remnants of a continuous soporator/fuscus

circumtropical ancestral distribution, subse-

quently extinct on the eastern Pacific main-

land coasts, or represent the eastward periph-

ery of Bathygobius dispersal across the Pacif-

ic in the equatorial countercurrent (Houve-

naghel 1984), perhaps excluded on the conti-

nent by established r a m o s u s and a n d re i .

Other Indo-West Pacific fishes are known

from the Galapagos province and Clipperton

Island (Briggs 1974, Grove & Lavenberg

1997) but do the three subspecies of lineatus

represent the products of secondary local dis-

latter view, and ramosus might be an eastern

Pacific derivative of western Atlantic sopora -

tor stock.

Like ramosus, B. andrei is a distinctive

Eastern Pacific endemic species. The occur-

rence of scales merely in the upper anterior

corner of the opercle, as seen in B. andreiand

B. arundelii, is a feature apparently unrecord-

ed among Indo-West Pacific and eastern

Atlantic B a t h y g o b i u s (Akihito & Meguro

1980, Hoese 1986, Miller & Smith 1989).

The presence of this character in the

Caribbean lepidopoma subspecies of B. cura -

cao is reported by Ginsburg (1947) and could

be viewed as indicating a western Atlantic

sister species, but opercular scales appear to

be variable in the eastern Pacific species and

this peculiar distribution of scales may be of

independent origin in each species. Elec-

trophoretic investigation of 26 gene loci in B.

soporator, B. andrei and B. ramosus revealed

that the two former species were closer genet-

ically than they were to B. ramosus and pre-

dicted divergence time between andrei and

soporator ancestry agreed well with the rise

of the Central American land bridge (Gorman

et al. 1976).

TABLE 4

Body proportions of Bathygobius andrei, from Guatemala and Panama (paratypes of B. a. heteropoma), as percentage

of standard length. Values are range, and, in parentheses, mean and standard deviation; n, number of observations.

Locality Guatemala Panama (heteropoma) Guatemala Panama (heteropoma)

Sex males males females females

SL(mm) 45-118 47-96 54-89 47 60.5

n 5 4 6 1 1

H 28.4-32.2 (29.9,1.35) 25.3-30.6 (27.4,2.36) 28.7-31.5 (29.6,1.00) 31.9 25.6

SN/Dl 36.7-38.9 (37.7,0.92) 33.3-37.9 (35.7,1.89) 36.5-41.4 (38.3,1.80) 41.5 35.5

SN/D2 56.7-57.8 (57.4,0.63) 54.0-57.4 (56.0,1.66) 55.9-60.5 (58.1,1.96) 67 57

SN/AN 52.7-55.6 (54.4, 1.56) 50.0-54.0 (52.6,1.79) 55.1-59.3 (56.6,1.62) 63 52.9

SN/A 57.5-61.1 (59.3,1.30) 56.4-58. 9 (57.3,1.09) .58.8-63.6 (61.4,1.63) 33 28.1

SN/y 28.8-31.1 (30.2,1.18) 27.7-29.3 (28.8,0.77) 28.4-30.6 (29.9,0.84) 28.4 26.1

V/AN 22.5-25.3 (24.0,1.07) 22.9-24.8 (23.8,0.77) 23.7-28.5 (25.8,2.10) 28.9 22.5

Cl 25.6-30. 0 (28.1,2.03) 18.4-25.8 (22.8,3.54) 25.0-29.9 (27.6,1.90) 27.7 24

Pl 22.1-25.1 (23.4,1.11) 16. 8-21.9 (20. 0,2.21) 21.8-24.8 (23.5,1.13) 19.6 23.2

Vl 18.0-22.6 (20.8,1.61) 18.4-20.7 (19.9,1.03) 20.3-22.3 (21.5,0.69) 22.4 19.6

CPd 11-8-14.2 (13.3, 0.87) 13.6-15.0 (14.3,0.56) 13.3-14.3 (13.8,0.43) 16.8 13.2

Hw 16.0-17.8 (16.5,0.71) 15.9-17.7 (17.1,0.83) 15.3-17.4 (16.5,0.70) 19.6 17.4

SN 6-5-7.2 (6.8, 0.25) 5.5-7.9 (6.7,1.01) 6.6-8.5 (7.3,0.70) 7.6 6.1

E 6.1-9.6 (7.7,1.48) 6.1-8.0 (7.2,0.87) 7.3-8.3 (7.8,0.36) 9.5 7.5

Po 14.4-16.8 (15.3,0.94) 12.9-15.3 (14.3,1.17) 14.4-16.7 (15.6,0.77) 15.9 14.1

Uj1 9.7-12.3 (10.9,1.00) 9.4-10.1 (9.7,0.50) 9.9-11.5 (10.4,0.66) 11.1 9.2

E/PDsc 3.7-4.8 (4.2,0.44) 3.0-3.2 (3.1,0.11) 1.6-4.4 (2.9,1.04) 2.5 -

I 1.7-5.1 (3.1,1.17) 3.9-6.7 (5.2,1.16) 1.8-4.5 (3.0,1.03) 3.7 3.6

155

ubica B. arundelii (Garman 1899) y B. l. lupinus Gins-

burg 1947 como subespecies de lineatus.

REFERENCES

Akihito, Prince & K. Meguro. 1980. On the six species of

the genus Bathygobius found in Japan. Japan. J.

Ichthyol. 27: 215-236.

Akihito, Prince, M. Hayashi & T.Yoshino. 1988. Subor-

der Gobioidei. p. 236-289. In K. Masuda, C.

Amaoka, C. Araga, T. Uyeno, & T.Yoshino (eds.).

The Fishes of the Japanese Archipelago, 2nd ed.

Tokai University Press, Tokyo.

Allen, G. R. & D. R. Roberstson. 1994. Fishes of the

Tropical Eastern Pacific. University of Hawaii

Press, Honolulu, 332 p.

Bleeker, P. 1878. Quatrième mémoire sur la faune ichthy-

ologique de la Nouvelle-Guinée. Arch. néerl. Sci.

nat. 13: 35-66.

Böhlke, J. E. & C. C. G. Chaplin. 1968. Fishes of the

Bahamas and Adjacent Tropical Waters. Liv-

ingston, Philadelphia, 771 p.

Briggs, J. C. 1974. Marine Zoogeography. McGraw-Hill,

New York, 475 p.

De Buen, F. 1923. Gobius de la Península Ibérica y

Baleares. Grupos Lesueurii, Colonianus, Affinis, y

Minutus. Mem. Inst. esp. Oceanogr. 3: 121-266.

persal from an Eastern Pacific centre such as

the Galapagos or is the morphological species

lineatus actually polyphyletic with some fus -

cus -type Bathygobius having traversed the

Pacific on a number of occasions ? Such

questions, and hypotheses of relationship

based of necessity on potentially very homo-

plasious morphology, will be addressed by

molecular studies which are now in progress.

ACKNOWLEDGMENTS

We are grateful to the late C. E. Dawson,

K. Hartel, S. Jewett, J. McCosker, R. Robert-

son, S. Smith, J. van Tassell, and A. C.

Wheeler for material, access to collections,

and/or information.

RESUMEN

Se define el género Bathygobius Bleeker y se

redescriben tres especies del Pacífico Oriental. Se

reconoce las especies B. ramosus Ginsburg 1947 y B.

andrei (Sauvage 1880). B. ramosus está en Revillagige-

dos y Cocos. Se define B. lineatus (Jenyns 1842) y se

Table 5

Body proportions of Bathygobius lineatus, from Marchena Island, Galápagos, and Clipperton Island (including holo -

type of Gobius arundelli), as percentage of standard length. Values are range, and, in parentheses, mean and standard

deviantion; n, number of observations

Locality Marchena Island Clipperton Island

Sex males females males females