Larval blennies from the Galapagos and Cocos Islands: families Tripterygiidae, Dactyloscopidae, and Chaenopsidae (Perciformes, Blennioidei)

15 Pages·2002·13.3 MB·English

by  Guillermo A Herrera

Larval Blennies erom the Galapagos and
Cocos Islands: Families Tripterygiidae,
Dactyloscopidae, and Chaenopsidae
(Percieormes, Blennioidei)
Guillermo A. Herrera^ and
Robert Lavenberg^
J.
ABSTRACT. Postflexion larvae of ten eastern Pacific blennioid species from the Galapagos Islands and
Cocos Island aredescribed. Threefamiliesaretreated:Tripterygiidae,Dactyloscopidae,andChaenopsidae.
The identifications were based on meristic data, and on comparisons ofmorphology between adults and
large larvae. The larvae from the Galapagos Islands are Lepidonectes corallicoia (Tripterygiidae); Dacty-
loscopuslacteus,Myxodagnussagitta,Platygillellusrubellulus,andGHlellussemicinctus(Dactyloscopidae);
andAcanthemblemaria castroiand Chaenopsisschmitti (Chaenopsidae).ThelarvaefromCocosIslandare
Dactyloscopus pectoralis fallax (Dactyloscopidae); and Acanthemblemaria atrata and Stathmonotus sp.
(Chaenopsidae).
All larvae described herein possess the following characters: a relatively long and slender body; a me-
lanophore anterior to the tip of the cleithral symphysis; ventral midline melanophores between pterygio-
phoresoftheanalfin;andasmallheadwithashortandgenerallyroundedsnout(exceptindactyloscopids
and in the chaenopsid Chaenopsis schmitti). Larvae of Lepidonectes corallicoia (Tripterygiidae) have a
specificarrangementofmelanophoresonthepterygiophoresofthethirddorsalfinandatthebaseofspines
of the second dorsal fin; pigment is found ventrally on the caudal peduncle and on the posterior margin
ofthe hypural plates. Larvae ofthe dactyloscopids {Dactyloscopus lacteus, Myxodagnussagitta, Platygil-
lellus rubellulus, and Gillellus semicinctus) have large and pointed heads, short preanal length (30-35%
standard length (SL)), and prominent dorsal and anal fins. The dactyloscopid larvae can be identified by
specific combinations of characters: presence, number, and size of head melanophores; presence of pig-
mentation along dorsal margin of the body; presence of melanophores on the hypural borders; and fin
structure and meristics. Most chaenopsid larvae possess a large and elongate melanophore in the midline
alongthe basipterygium, amelanophoreonthejawangle,pigmentdorsallytotheanus,andalongpreanal
length (40-50% SL). Characters described herein suggest that some larval attributes may be informative
for the elucidation ofphylogenetic relationshipswithin each family.
RESUMEN. Se describen las larvas en estado de postflexion de diez blenioideos del pacifico este de las
IslasGalapagosydeIsladelCoco. LasfamiliasconsideradassonTripterygiidae,DactyloscopidaeyChaen-
opsidae. Las identificaciones se basaron en informacion meristica y en comparaciones de morfologia de
adultos con larvas avanzadas. Las larvas de las islas Galapagos son Lepidonectes corallicoia (Tripterygi-
idae); Dactyloscopus lacteus, Myxodagnus sagitta, Platygillellus rubellulus y Gillellussemicinctus (Dacty-
loscopidae);yAcanthemblemariacastroiyChaenopsisschmitti(Chaenopsidae).LaslarvasdeIsladelCoco
son Dactyloscopus pectoralis fallax (Dactyloscopidae), y Acanthemblemaria atrata y Stathmonotus sp.
(Chaenopsidae).
Caracteristicas presentes en las larvas de todas las especies son: cuerpo relativamente largoyelongado,
unmelanoforoanteriordelasinfisisdeloscleitros,unahileraventraldemelanoforosentrelospterigioforos
de la aleta anal, y una cabeza pequeha con un hocico corto y redondeado (excepto en losdactiloscopidos
yelchaenopsido Chaenopsisschmitti). Laslarvasdelblenidodetresaletas,Lepidonectescorallicoia,tienen
una configuracion espedfica de melanoforos en los pterigioforos de la tercera aleta dorsal y en la base de
algunas espinas de la segunda aleta dorsal; tienen ademas pigmento ventral en el pedunculo caudal y en
el margen posterior de las placas hipurales. Los dactiloscopidos {Dactyloscopus lacteus,Myxodagnussag-
itta, Platygillellus rubellulus y Gillellus semicinctus) tienen larvas con una cabeza grande y puntiaguda,
una distancia preanal corta (30-35% longitud estandar (LE)) y aletas dorsal y anal prominentes. Las
especies pueden identificarse mediante combinaciones especificas de caracteres tales como presencia, nu-
mero y tamano de melanoforos cefalicos; presencia de pigmento dorsal sobre el cuerpo y en el borde
posterior de las placas hipurales; y caracteres meristicos de las aletas. Las mayoria de las larvas de los
chaenopsidos poseen unmelanoforograndeyelongadoventralal basipterigio, unmelanoforoenelangulo
mandibular, pigmento dorsal sobre el ano, y una mayor distancia preanal (40-50% LE). Los caracteres
larvalesdescritosenestetrabajosugierenquealgunosatributospuedenserinformativosparalaelucidacion
de relaciones filogeneticas dentro de cada familia.
Contributions in Science, Number488, pp. 1-15
Natural HistoryMuseum ofLos Angeles County, 2002
INTRODUCTION the larvae ofthree species fromCocosIsland,Costa
Rica, are included. The material considerspostflex-
The blennioids are oviparous fishes (except for ion larval stages and some juveniles. Larvae ofthe
threeviviparousgenera) thatlaytheireggsattached following species are described: Tripterygiidae,
to a nest substrate, and exhibit male parental care. Lepidonectes corallicola (Kendall and Radcliffe,
The larvae are elongate and hatch with pigmented
1912); Dactyloscopidae, Dactyloscopus lacteus
e1y9e8s4;aSntdepisepna,rs1e986p;igWmaetnstoant,io1n99(6M)a.tCaroemsemoent faeha,- ((MDyaewrsson,an1d975W)a,deM,yxo19d4a6g)n,usD.sagpietcttaor(aMlyisersfalalnadx
tures are the presence of large melanophores dor- Wade, 1946), Platygillellus rubellulus (Kendall and
sally on the swimbladder and gut and small mela- Radcliffe, 1912), and Gillellussemicinctus (Gilbert,
nophores along theventral margin ofthe trunk, be-
1890); and Chaenopsidae, Acanthemblemaria cas-
tween the pterygiophores ofthe long anal fin (Wat-
troi (Stephens et al., 1966), A. atrata (Hastingsand
son, 1996; Cavalluzzi, 1997).
Robertson, 1999), Chaenopsis schmitti (Bohlke,
The sizes of larvae at hatching and flexion vary 1957), and Stathmonotus sp. The larvae ofD. pec-
depending on the species (Matarese et ah, 1984),
and the larvae do not show striking pigment pat- toralis fallax, A. atrata, andStathmonotussp. were
collected in Cocos Island. Larvae of six species of
terns or morphological adaptations for pelagic life.
Aside from some Blenniidae, the larvae of most the familyLabrisomidae (fromthesevenspeciescit-
ed for the archipelago) were described separately
blennioid families are largely limited to coastalwa-
(Herrera and Lavenberg, 1999).
ters (Watson, 1996). Indeed, some larvaehave been
observed to remain actively in coastal areas as they
MATERIALS AND METHODS
school in groups around kelp and other algae (Ste-
pien et ah, 1997). Most ofthe plankton samples were collected by the RW
anFdemwoschtaroafcttehresmarheavseharbeedenbysualmlmbalreinzneodidblyarMvaae-, cVreuliesreos ItIoI,thdeureaisntgertnhePaAcilfliacnaHnadnGcaolcakpaPgaocsifiIcsleanxdpse.diStaimo-n
tarese et al. (1984), Watson (1996), and Cavalluzzi pling sites included Espanola, Santa Maria, Santa Cruz,
(1997). These are: body moderately elongate; pre- Isabela, Baltra, and Genovesa Islands (Eraser, 1943). A
anal distance between 30 and 50% ofthe standard singlesamplewascollectedinChathamBay,CocosIsland,
length (SL); large swimbladder; melanophores on Costa Rica. Samples were normally collected at night (at
the ventral margin of the trunk (between pterygio- anchorage),usinganelectriclightanddipnets.Thelarvae
phores of the anal fin); a melanophore on the tip arehousedinthe larvalfishcollectionattheNaturalHis-
o1f99t9h)e;calenidthsriaxl bsryamnpchhyisoisste(gHaelrrraeyrsa.and Lavenberg, itomreynsMuwesreeummeaofsuLroesdAtnogetlheesneCaoruesntty0.(1LmACmM)a.ndTihlelusstpreact--
Matarese et al. (1984) summarized the larval ed with a camera lucida. The size range of the series il-
characters ofsome Blennioidei, at a time when not lustrated was determined by the available material. Al-
many descriptions were available. The best known though the larval series are not complete because of the
sporadicnatureofthesampling,theystillcontainvaluable
larvae are those ofthe familiesBlenniidaeandTrip- ontogenetic information. Meristic data were obtained
terygiidae, probably because of their wider distri- from collection specimens and from the literature. Mea-
butions and greater species numbers. The knowl- surements anddefinitions followthoseofLeisandRermis
edge of the larvae ofthe other four families, which (1983).
are predominantly from the New World, has in- The larvae ofthe three species ofBlenniidae from Gal-
creased in recent years with the descriptions oflar- apagos, Hypsoblennius brevipinnis (Gunther, 1861),
vae from the GulfofCalifornia (Brogan, 1992),the Ophioblennius steindachneri (Jordan and Evermann,
California Current region (Watson, 1996), and the 1898), and Plagiotremmus azalea (Jordan and Bollman,
western Atlantic (Cavalluzzi, 1997). The larvae of 1890),were also found togetherwiththe larvaedescribed
species from the southeastern Pacific are less well here and in a previous work (Herrera and Lavenberg,
known (Balbontin and Perez, 1979; Perez, 1979). 1999). These three species have a wide distributional
range in the eastern Pacific and their larvae have been
Nineteen Blennioidei are known from the Gala- describedfromthe Californiaregion (Watson, 1996).Lar-
pagos Islands, twelve ofwhich are endemic (Grove vae of another blennioid, the dactyloscopid Dactylagnus
and Lavenberg, 1998). They belong to the families mundus (Gill, 1862), were not found in the samples.
Tripterygiidae (one species), Dactyloscopidae (five
species), Blenniidae (three species), Labrisomidae RESULTS
(seven species), and Chaenopsidae (three species).
No species of the family Clinidae are known from The following descriptions include general charac-
the archipelago. In this paper, field-collected speci- terizations of morphology, dorsal- and anal-fin de-
mens mainly from the Galapagos Islands, obtained velopment, and pigmentation. The larval series are
from plankton samples collected during the Allan limited by the available material collected. For
Hancock expeditions, are described. Additionally, those species represented by a few individuals the
descriptions are restricted to a usually narrow size
1-2. Natural History Museum of Los Angeles County, range. Meristic data and informationaboutpreanal
Research and Collections, 900 ExpositionBoulevard,Los distance, a helpful diagnostic character of larval
Angeles, California 90007. blennioid families, are summarized in Table 1.
2 Contributionsin Science, Number488 Herrera and Lavenberg: Larval blennies from Galapagos
1
-3o O McCosker
Reference
r\ h-
fN (N uo ^ rT and
(%)
O ^
rr> ^ ro CD ro <N (4N 4 TTf T T Rosenblatt
Preanal 4- oo ro O ro r^o ^
distance ro r\l ro ro ro
(8)
(1996);
Ventral gut
study.
+ + + + + +
this I Watson
in
(7)
+ +
border I i
Hyp.
included (1977);
Pigmentation
Dorsal trunk I + + I I i I
Dawson
Chaenopsidae
<u ^ (6)
bJD.is
Dorsal head
and T-l (N (1974);
+ + + + +
I I I
Blenniidae, lya rT) Dawson
m a^-) a^-) ^
PT'" roI C^N
(5)
(1975);(1994).
OJ
Dactyloscopidae, AnaP' Oor'oo] of(rNoNnr^m7rf\n2r,Vdo(NO\1r, O7oroO2 rs rr(x-N1|l \(OrNDO 4(VNOf. f(oNNo rronno o7(lNo12 _o<XQu Dawson Springer
4-.
(4)and
Tripterygiidae,
(1992);
fN ^I ^ >rdon ro rrna rVnO ft—N <N Hastings
of DorsaP" X > ra rn1 XX XX Brogan(11)
species X X XX SX4X X >I NXKd> 1XXI, XX1 X>1 sXX >XX (3)(1966);
for
Galapagos. (1976);al.
data m Tro Tro ^tTO i^ '1sD tT\ et
Vertebrae VOI or^o oroo ^ oCoD 3- ro tihne DawsonStephens
morphologic
(2)
present (10)
and but Island. (1991);
(1963);
meristic S csu .S Q c samples Cocos Bussing
Species I V) ^V> 'tbaoo s s -6 trUt XeI in from (1)Stephens
TS1ealebc.lteed ^So-s4. -_’QouCurSao/t5h Q<3 QQ IQ l^Slh3:soS 7"<nc<2Suu -Soa.•o•i2s d‘1oS::b U'Oq<o0;uo4 s-<5uK^3 £~^S^Su3i -OSQg^; -o-5QosnS; ^I u§ ftNoountd C#ollectedReferences: ((19988));
CQ
Contributions in Science, Number488 Herrera and Lavenberg: Larval blennies from GalapagosI3
DESCRIPTION OF LARVAE is observed. Additional pigment includes a lateral
band of small melanophores extending from the
Family Tripterygiidae
pectoral-fin base to the end ofthe caudal peduncle.
Asingletriperygiidoccursinthe GalapagosIslands, REMARKS. Below 10.0 mm SL, the larvae are
the endemic Lepidonectes corallicola. In general, similar in appearance to some labrisomids, espe-
the larvae of the Tripterygiidae are elongate and cially those species lacking preopercular spines.
slightly compressed; have small short and rounded However, pigmentation, meristics, and morpho-
heads with no spination; have dorsal, anal, and metriescan differentiatethem. InL. corallicolador-
pectoral fins that develop early (shortly after flex- salmidline melanophoresdevelopfromposteriorto
ion); and have the spines of the first dorsal and on anterior (oppositeforMalacoctenuszonogaster,La-
the anal fins that form last (Leis and Rennis, 1983). brisomidae), length to the origin ofthe third dorsal
fin is 60-63% SL in L. corallicola (68-71% SL in
Lepidonectes corallicola M. zonogaster), andpreanaldistance is41-43% SL
(Kendall and Radcliffe, 1912) in L. mcomrallicola (38-41% in M. zonogaster). After
10.0 SL, the presence of three distinct dorsal
Figure 1 fins in L. corallicola separates this species fromthe
MATERIAL EXAMINED. From 2,281 speci- labrisomids.
mens (6.2-18.3 mm SL), five are illustrated;LACM
45614-6 (8.3, 10.0, 13.0, and 15.1 mm SL) and Family Dactyloscopidae
LACM 45621-17 (17.2 mm SL).
gatMeOR(pPrFeaInOalLOlGenYg.thT4h1e-”b4o3d%y ibsomdoyderleantgetlhy (eBlLo)n)- WTohreldfa,miilnytDhaectPyacliofsiccopainddaeAtilsarnetsitcricOtceedatnos.theANfeeww
with a small head and rather small and rounded descriptions of dactyloscopid larvae from the Gulf
snout. Flexion completed by 8.0 mm. Anal fin, ofGalifornia (Brogan, 1992), Baja California (Wat-
third dorsal fin, and pelvic fins are apparent by 8.0 son, 1996), and the Atlantic (Cavalluzzi 1997) are
mm. First and second dorsal fin apparent by 13.0 available. From these, the larvae of the sand star-
mm SL. Pores of the preopercular and circumor- gazers can be characterized as having an elongate
bital sensory canal systems are evident by 17.2 body, a short and compact gut, long and relatively
mm SL. high dorsal and anal fins, jugular pelvic fins, 5+5
PIGMENTATION. In small larvae (6.2 mm) a principal caudal rays, and a large head with point-
single dorsal melanophore is present on the nape; ed snout and no cirri. The preanal length is short,
this melanophore becomes embedded withgrowth. comparedto thatofotherfamilies, andrangesfrom
Other cephalic pigmentation includes a pair ofme- 28-35% SL (seeTable 1). ThespeciesfromtheGal-
lanophores onthe hindbrain (Figs, la-b),whichin- apagos show specific arrangements ofcephalic, hy-
creases to three pairs with the appearance of pairs pural, andtrunkpigment. Theposterodorsalregion
on the midbrain and forebrain (Fig. le). Gut pig- of the swimbladder is pigmented, but it is difficult
ment consists ofa single melanophore located ven- to see the melanophores, especially in larger or
troanteriorly (behind insertion of the pelvic fins). more robust larvae (such as Dactyloscopus).
mm
By 8.3 SL three to five melanophores are
present on the ventral midline ofthe caudal pedun- Dactyloscopus lacteus
cle, and the posterior margins of the upper and (Myers and Wade, 1946)
lower hypural plates each possess a single mela- Figure 2
nophore. By 10.0 mm, dorsal midline melano-
phores are associated with the posterior portion of MATERIAL EXAMINED. Only two specimens
the third dorsal fin, and the posterior marginofthe collected; LACM45628-5 (7.7mm SL) andLACM
mm
upper and lower hypural plates each possess two 45617-2 (9.2 SL).
melanophores. By 15.1 mm SL, the second dorsal MORPHOLOGY. The head is large and deep
fin has a single melanophore at the base of spines with a pointed snout and a slight projection ofthe
1, 3, and 7-11 (rarely associated with spines 2 and tip of the lower jaw. Preanal length reaches 31-
6), the third dorsal fin has a single melanophore at 34% SL. The larvae lack a notch on the ventral
the base of each soft ray, the posterior margins of margin of the caudal peduncle, a character that is
the dorsal and ventral hypural plates have a wide present in adults of many Dactyloscopus species
band ofpigment, two melanophores are presenton (Dawson, 1975). At 7.7 mm, the anal-fin rays are
the upper jaw, and small melanophores pepper the longer and more prominent than the dorsal-fin
membrane between rays of the caudal fin, mainly rays, indicating thatthe anal findevelopsearlier.At
mm
in the lower half. By 17.2 SL, the juvenilestage this size, only the rayed portion of the dorsal fin
Figure 1 Larvae of Lepidonectes corallicola: (a) 8.3 mm (b) 10.0 mm (c) 13.0 mm (d) 15.1 mm (LACM 45614-6)
(e) 17.2 mm (LACM 45621-17)
4 Contributionsin Science, Number 488 Herrera and Lavenberg: Larval blennies from Galapagos
Contributionsin Science,Number488 Herrera and Lavenberg: Larvalblennies from Galapagos 5
mm
has developed (Fig. 2a). By 9.2 all dorsal-fin Dactyloscopus pectoralis fallax
spines have formed although they are not yet at (Dawson, 1975)
their maximum length and sensory pores have Figure 3
formed on the preopercular border, the ventral
2mba)r.gin of the lower jaw and below the eye (Fig. gleMAspTeEciRmIenA,LLEAXCAMMI4N5E6D5m.8mD(1e0s.c0rimptmionSLo)f,afrsionm-
PIGMENTATION. In addition to the pigmenta- three larvae (all near 10.0 SL) collected in Co-
ttiyolnosacnotpeursiolracttoeutshehatsipaonfotthheerbassmailpltermyegliaunmo,pDhaocr-e cosMOIsRlaPndH,OCLosOtGaYR.icaT.he body shape is similar to
olannothpehobraessipatreervyegriyumc,locsleosaendtoustuhaelltiyp.diTffhieculttwtoomdies-- stishpai3tn0eso-f3h2Daav%cetBnyLol.toAsytceot1p0fu.os0rmmleacmdt,eSuwsLh.ihTcehhaedmppaoryreeadsniafoflrerdloefrnrsgoatmlh
tinguish from each otherwhen expanded. Two large D. lacteus, because the latter species had them by
dendritic melanophores are present; one dorsally on 9.2 mm (see Fig. 2b). The soft dorsal has formed
the head, and the other ventrally on the gut. No although it has not reached its maximum size, and
melanophores occur dorsally along the trunk or on the dorsal spines are small projections.
the caudal peduncle. The posterior margins of the PIGMENTATION. Dactyloscopuspectoralisfal-
hypural plates are pigmented. This differs from D. lax has a single dendritic melanophore dorsally on
pectoralis (Brogan, 1992), D. byersi(Watson, 1996), the head and anotherventrally on the gut. The sole
and D. pectoralis fallax (Dawson, 1975). difference between D. pectoralis and D. pectoralis
Figure 3 Larva ofDactyloscopuspectoralisfallax: 10.0 mm (LACM 45658-2)
6 Contributionsin Science, Number488 Herrera and Lavenberg: Larvalblennies from Galapagos
Figure 4 Larvae of Myxodagnus sagitta: (a) 7.3 mm (b) 8.8 mm (LACM 45625-7) (c) 11.6 mm (LACM 45623-10)
(d) 13.4 mm (LACM 45625-7)
fallax is the presence in the former of several me- preanal distance (28-30% BL). The anal- and dor-
mm
lanophoresventrallyonthegut (Brogan, 1992)that sal-fin rays have developed by 7.0 (Fig. 4a),
are not present in the latter. However, more speci- whereas the dorsal spines develop later (Fig. 4c)
mens ofD. pectoralis fallax should be examined to The head is deep in small larvae, as in most dac-
determinewhetherthis pigmentappears laterinthe tyloscopids, but becomes depressed with develop-
ontogeny. ment. The anterior projection of the lower jaw is
slightin small larvae, and increaseswithsize. Pelvic
Myxodagnus sagitta fins develop at an early stage (Fig, 4a), but they
(Myers and Wade, 1946) remain smaller than in all other species ofthe fam-
Figure 4 ily.
PIGMENTATION. The cephalic pigmentation
MATERIAL EXAMINED. From a total eighty- pattern of Myxodagnus sagitta resembles that of
two specimens collected, in the size range of 7.0- Dactyloscopus lacteus, with a large dendritic me-
14.0 mm, four are used for description; LACM lanophore above the head and below the gut. Fur-
45625-7 (7.3 and 8.8 mm SL), LACM 45623-10 thermore, a melanophore is present at the base of
(11.6 mm SL), and LACM 45625-7 (13.4 mm SL). each dorsal ray, except in the last one to two rays.
MORPHOLOGY. Among the larval dactylos- A small melanophore develops on the ventral mar-
copidsstudied,thisspecieshasthemostslenderand gin ofthe caudal peduncle; these melanophores are
elongate body, the smallest head, and the shortest lacking in M. opercularis (Brogan, 1992; Watson,
Contributionsin Science,Number488 Herrera and Lavenberg: Larvalblennies from Galapagos 7
a
Figure 5 Larvae ofPlatygillellus rubellulus: (a) 8.9 mm (LACM 45614-11) (b) 11.1 mm (LACM 45621-10)
1996). In smaller larvae, the posterior edge ofeach occur dorsally on the head; a large pair above the
hypural plate has one small melanophore on the midbrain, and a small pair overthe forebrain. Asin-
border; these melanophores increase with develop- gle melanophore is present on the nape. Except for
ment forming bands ofpigment. Insomespecimens a small single melanophore before the anus, no ven-
a small melanophore develops directly anterior to tralmelanophores arefoundonthegut, Asingleand
the anus (Fig. 4d). small melanophore occurs on the ventral margin of
the caudal peduncle just behind the last anal-finray.
Platygillellus rubellulus Another ventral midline melanophore is found im-
(Kendall and Radcliffe, 1912) mediately anterior to the ventral hypural plate. This
Figure 5 melanophore varies in position from the space be-
MATERIAL EXAMINED. Two specimens, out tween fourth and fifth caudal rays (lower hypural),
mm on the fifth ray, in the space between the last two
odLefAsfcCirfiMtbeeedn4;5c6ol2Ll1Ae-c1Cte0Md((1s41i.5ze161rm4an-mg1e1SL8).(.08-.911.m1m SLS)L)aanrde pfirrostcuprrroecnutrrceanutdaclaurdaayls,raay.nd slightly in front of the
MORPHOLOGY. The body shapes of Platygil- Gillellus semicinctus (Gilbert, 1890)
lellus rubellulus and Dactyloscopus lacteus larvae
Figure 6
are similar in having large heads and deep bodies
anteriorly, but differing in cephalic pigmentation. MATERIAL EXAMINED. Of the forty speci-
The preanal length reaches 33-35% BL, which is mens collected, three are used for description:
the longest among the studied dactyloscopids. At LACM 45614-19 (6.5, 10.0, and 12.4 mm SL).
11.1 mm, three pores occur above the eye and one MORPHOLOGY. The larvae are more elongate
occurs on the margin of the lower jaw. The dorsal than those of Dactyloscopus lacteus and the head
fin is notched anteriorly, with the third spine short- is proportionally smaller. The preanal lengthreach-
er than the adjacent ones, anterior andposterior. In es 30-32% SL. Figure 6 shows the approximate
addition, the third and fourth spines are more sep- formational sequence of the dorsal- and anal-fin
arated from one another than other dorsal spines. spines and rays, and the subtle projection of the
mm
The last four dorsal spines decrease in size and first lower jaw with development. At 6.5 flexion is
four dorsal-fin rays increase progressively in size. complete, the anal fin is beginning to develop, and
The relative sizes of spines and rays resembles a the dorsal fin has not formed (Fig. 6a). In the larg-
doubly notched dorsal fin (Fig. 5b). est larva, 12.4 mm, the first three dorsal spines,
PIGMENTATION. Pigmentpatternisthesamein which are separated from the following spines in
both illustrated larvae. Two pairs of melanophores the form of a finlet, are present. Their lengths de-
8 Contributionsin Science, Number488 Herrera and Lavenberg: Larval blennies from Galapagos
Figure 6 Larvae of Gillellussemicinctus-. (a) 6.5 mm, (b) 10.0 mm, and (c) 12.4 mm (LACM 45614-19)
crease progressively from the first to the third (Fig. melanophore series occurs betweenpterygiophores.
6c). Posteriorly, the dorsal spines and rays are ap- The differences may be due to intraspecific varia-
proximately the same size, and the border of the tion or the larvae may belong to different species.
dorsal fin is straight.
PIGMENTATION. Pigment pattern does not REMARKS ON DACTYLOSCOPID LARVAE
change in the size range studied. The larvae of Gil-
lellus semicinctus have two or three small melano- The relationships between the eight dactyloscopid
phores ventral to the gut. One (or two in some lar- genera have been studied by Doyle (1998) using
vae) is always just posterior to the insertion ofthe morphological data. Heteristius is the basalmost
pelvic-fin rays, and the second is located more pos- taxon, and Platygillellus is the next basalmost tax-
teriorly next to the anus. A ventral and internal on. The remaining six genera are divided into two
melanophore is also present behind the cleithra. clades; one ofthemincludes Gillellus (togetherwith
Pigment is absent dorsally on the head, which is an Leurochilus and Sindoscopus) and the other com-
uncommon feature in the family that has been also prises Dactyloscopus, Dactylagnus, and Myxodag-
reported in larvae of two other species of Gillellus nus. Some of the larval characters presented here
from the western Atlantic, G. jacksoni and G. ur- are congruent with the relationships hypothesized
anidea (Cavalluzzi, 1997). This lack of pigment by Doyle (1998). A large, single, medial dendritic
may be a reductive specializationcharacterizingthe melanophore occurs dorsally on the head and ven-
genus. tral to the gut in the derived clade comprisingDac-
Watson (1996) described larvae of a Gillellus tylagnus, Myxodagnus, and Dactyloscopus. These
species, tentatively ascribed to semicinctus. Fiow- genera also share the same general body shape,
ever, in his series the pretransformation specimens with a straight anterior profile ofthe dorsal finand
(<13.3 mm) develop preopercular spines and a a shorter preanal distance. In the other derived
ventral series of melanophores at the anal-fin base clade, the larvae of Gillellus lack cephalic melano-
that is not continuous. The larvae described here phores, which represents a derived condition. Un-
do not have preopercular spines and a continuous fortunately, larvae of the other two genera of the
Contributions in Science, Number 488 Herrera and Lavenberg: Larvalblennies from Galapagos 9
clade, Leurochilus and Sindoscopus, are not Costa Rica, in the size range of 4.1-18.4 mm, are
known. illustrated: LACM 46011-1 (4.1 mm NL, 5.3 mm
The larvae ofthe phylogeneticallymoreprimitive NL, 6.9 mm SL, 11.8 mm SL), and LACM 45658-
Platygillellus show features that can be considered 1 (18.4 mm SL)
plesiomorphic and include small melanophores in MORPHOLOGY. The larvae are similar inmor-
pairs above the brain (vs. large and single), a longer phology and meristics to those of Acanthemble-
preanal distance (vs. shorter), a dorsal fin divided maria castroi, but differ slightly in pigmentation.
into regions (vs. straight margin), and several small The largest specimen (18.4 mm SL) has both single
ventral melanophores on the gut (vs. single and nasal cirri and single orbital cirri; while larval pig-
large). mentation is still present, heavy cranial spination
appears along with sensory pores of the mandibu-
Family Chaenopsidae
lar, nasal, occipital, preopercular, andorbitalseries.
The tube blennies are found in tropical and tem- The dorsal- andanal-finformationissimilartothat
perate coastal waters of the New World, in both ofA. castroi.
the eastern Pacific and westernAtlantic. Compared PIGMENTATION. The larvae of Acanthemble-
to other blennies, chaenopsid larvae have a rela- maria atrata show the same pigment pattern as A.
tively longer and straighter gut with a prominent castroi, but in addition exhibit a band of melano-
dorsallypigmentedswimbladder. Mostspecieshave phores on the posterior margin of the hypural
a large and elongatemelanophoremidventralatthe plates. Further, one or two melanophores develop
basipterygium area. Other larval charactersinclude ventrally on the anus (Figs. 8a-c); these melano-
the presence ofpigment dorsally to the anus,pelvic phores disappear during development (Figs. 8d-e).
fins that are inserted close to the base of the pec- A more complete larval series is described for this
toral fin, rugae in the gut, ventral pigment on gut species, which allows following of the formation
and breast, no dorsal pigmentation, and a broad pattern of the ventral melanophore on the basip-
and serrated premaxilla with a long ascendingpro- terygium. Two elongate melanophores develop lat-
cess (Brogan, 1992). erally in early stages, converging anteriorly in an
inverted V-shaped pattern, with the wings ofthe V
Acanthemblemaria castroi fusing alongthe midventralmargin (Brogan, 1992).
(Stephens et ah, 1966)
Figure 7 Chaenopsis schmitti (Boelke, 1957)
MATERIAL EXAMINED. From the 712 larvae Figure 9
mm
examined, in the simzemrange of 5.3 notochord MATERIAL EXAMINED. Only two specimens
4lsScLe5r)n6i,g4ptt4hLi-oA1(nsNC:(LM8).L4tA4om5Cm6m1M2m63N-4L15)6,2(11LS4-LA.1,0Cf(miM5v.em34w5meS6Lrm1)e4,-Nu1aLsn)e(d,d12LLf.o4AArmCCdemMM- cseoilldoMleneOrgceatRdteePdh;HebroLOed,ALy.CtOhTMiGshYe4s.p5pe6rcA1eim4eas-noa3nhlag(sl8e.atin0lhgeatthnhmedroabs1nlt4ge.ens6nsliemfonirdmdoesmrScL4ao)0nn.d--
45M61O4R-1PH(1O6L.0OGY.SL)L.arvae are characterized by 44% BL. The snout is mpominted and increases in
elongate body, preanal length of40-44% BL, small length with size. At 8.3 SL only the posterior
rays of the dorsal fin are developed, whereas anal-
and rounded head with a short snout, developing fin rays are just forming. By 14.6 mm, the rayed
cbiufrisdanfatsearl5c.i3rrmi,manadndbifiisdcoormbpiltealtecibrryi.1F0l.e0xmiomn,oca-t paonrdtitohneodforbsoalt-hfitnhespdionressalaraenadppaenaalrifnign.are formed,
which time the dorsal and anal-fin rays develop. PIGMENTATION. The larvae of Chaenopsis
The dorsal spines begin to develop by 12.0 mm.
PIGMENTATION. In addition to the general schmitti possess single melanophores at the man-
dibular angle, midlaterally on the preoperculum,
blennioid pattern, the larvae ofAcanthemblemaria andonthehindbrain. Nomelanophoresarepresent
castroi have melanophores that become embedded
on the caudal peduncle.
during developmentlocatedabovetheswimbladder
and anusm; ma melanophore on the mandibular angle Stathmonotus sp.
by 12.4 SL (Fig. 7c); a single melanophore on
Figure 10
the nape that becomes partially embedded with
growth (Figs. 7b-e); and three to four small mela- MATERIAL EXAMINED. A single specimen
nophores that are present during all stages on the was collected in Chatham Bay, Cocos Island, Costa
ventral midline ofthecaudal peduncle (Fig. 7a).No Rica; LACM 45634-15 (8.3 mm SL). Although the
pigment occurs ventrally on the gut, or on the pos- genushas notbeenreportedthere,thespecimencan
terior border of the hypurals. be tentatively ascribed to the species Stathmonotus
Acanthemblemaria atrata culebrai based on meristic data. Also, 5. culebraiis
the only species of the genus from Pacific Central
(Hastings and Robertson, 1999)
America (Hastings and Springer, 1994).
Figure 8 MORPHOLOGY. The general shape ofthe larva
MATERIAL EXAMINED. Five larvae froma to- is similar to that of Stathmonotus stahli and S.
tal of214 collected in Chatham Bay, Cocos Island, hemphilli (Brogan, 1992; Cavalluzzi, 1997), with a
10 Contributionsin Science, Number488 Herrera and Lavenberg: Larval blennies from Galapagos