New records of benthic hydroids (Cnidaria: Hydrozoa) from the coast of Oaxaca, Mexico
Author
Humara-Gil, Karla J.
Author
Cruz-Gómez, Christopher
text
Zootaxa
2018
2018-08-03
4455
3
454
470
journal article
29088
10.11646/zootaxa.4455.3.3
5d4c94cd-6652-4da8-829f-577cd3798f1b
1175-5326
1457449
BBEB2AB8-50D6-44F1-ABDC-F2A25FF814FF
Obelia
dichotoma
(Linnaeus, 1758)
FIg. 5
Sertularia dichotoma
LINNAEuS, 1758: 812.
Clytia longicyatha
.—FRASER, 1938A: 32.
Obelia tenuis
FRASER, 1938A: 38, pL. 9, fIG. 42.
Obelia commissuralis
.—FRASER, 1938A: 36.—FRASER, 1948: 213.
Obelia
dichotoma
.—FRASER, 1938A: 36.—FRASER, 1948: 213.—
MILLARd, 1975
: 227, fIG. 75F‒H, J (SyN.).—CALdER, 1991: 72, fIG. 38 (SyN.).—KELmO & AttRILL, 2003: 138, fIG. 6G‒I (SyN.).—OkOLOdkOV
et al.
, 2007: 40.—CALdER, 2012: 50, fIG. 51 (SyN.).—
CuNhA
et al
., 2017: 118.
Obelia hyalina
.—FRASER, 1938A: 37.—FRASER, 1938c: 133.—FRASER, 1948: 215.
Obelia plicata
.—FRASER, 1938A: 38.—FRASER, 1938b: 109.—FRASER, 1948: 215.
Obelia biserialis
FRASER, 1948: 213, pL. 24, fIG. 6.
Obelia
gracilis
.—FRASER, 1948: 215.
Obelia griffini
.—FRASER, 1948: 215.
Type
locality.
COAST
Of
SOUThWEST
ENgLANd
(CORNELIUS 1975).
Material examined.
NINE
cOLONIES: UMAR-HYDR-007, fIVE cOLONIES ON
Rhizophora mangle
(
CORRALERO
BAY
,
OAXAcA
,
16°13’04’’N
98°11’11’’W
,
1 m
,
11
JUNE
2015
, cOLL. C. CRUZ-GómEZ); UMAR-HYDR-008, fOUR cOLONIES (MAZUNTE,
OAXAcA
,
15°39’46’’N
96°33’55’’W
, ~
20 m
,
15 SEPTEmbER 2015
, cOLL. F. RUIZ-EScObAR).
Description.
COLONIES EREcT,
0.7–1.1 cm
hIgh, SYmPOdIAL; ARISINg fROm A cREEPINg hYdRORhIZA. HYdROcAULUS mONOSIPhONIc, UNbRANchEd, ZIgZAg; dIVIdEd INTO INTERNOdES AT REgULAR INTERVALS. INTERNOdES SLIghTLY cURVEd, WITh TWO OR ThREE ANNULATIONS bASALLY; EAch ONE SUPPORTINg A hYdROThEcAL PEdIcEL ORIgINATINg fROm AN APOPhYSIS. PERISARc UNIfORm, ThIcK; TRANSLUcENT (CORRALERO BAY SPEcImENS) OR bROWNISh (MAZUNTE SPEcImENS). APOPhYSES ShORT, ALTERNATE. PEdIcELS fROm 450 µm TO
1 mm
LONg; WITh AbOUT EIghT ANNULATIONS PROXImALLY ANd SIX dISTALLY. HYdROThEcAE cAmPANULATE, UP TO 200 µm LONg, 275 µm WIdE AT mARgIN; TAPERINg AT bASE. HYdROThEcAL mARgIN NOT cOmPLETELY SmOOTh bUT WITh 12 SOfTLY cURVEd, ALmOST INdISTINgUIShAbLE LObES; SOmETImES ENTIRE. HYdRANThS WITh AbOUT 25 TENTAcLES, 180–200 µm LONg. GONOThEcAE cONE-ShAPEd, WITh SmOOTh WALLS; ELONgATEd, 500 µm LONg fROm bASE TO APERTURE, 300 µm WIdE (mAXImUm WIdTh); WITh A ShORT NEcK ANd dISTAL APERTURE; ARISINg fROm ANNULATEd PEdIcELS.
Remarks.
ThE mORPhOLOgY Of cOLONIES fROm
OAXAcA
cOINcIdES WITh dEScRIPTIONS Of
Obelia
dichotoma
fROm
SOUTh AfRIcA
bY
MILLARd (1975)
; fROm
BERmUdA
bY CALdER (1991); ANd fROm
BRAZIL
bY KELmO & ATTRILL (2003). ALThOUgh ThIS SPEcIES hAS bEEN REcORdEd IN OThER STATES ALONg ThE PAcIfIc cOAST Of
MEXIcO
, SUch REcORdS NEEd VERIfIcATION bEcAUSE Of ThE gREAT dISTANcE bETWEEN
MEXIcO
ANd ThE
TYPE
LOcALITY,
ENgLANd
. MOREOVER, SIgNIfIcANT dIffERENcES EXIST IN ENVIRONmENTAL cONdITIONS bETWEEN ThE TWO REgIONS, PARTIcULARLY IN WATER TEmPERATURES.
Obelia
dichotoma
IS cONSIdEREd A cRYPTOgENIc SPEcIES bY SOmE AUThORS (OKOLOdKOV
et al
. 2007) bEcAUSE Of ITS mULTIPLE REcORdS AROUNd ThE WORLd.
FURThERmORE,
O.
dichotoma
IS AmONg ThE mOST mORPhOLOgIcALLY VARIAbLE hYdROIdS (CORNELIUS 1990). ThOSE VARIATIONS ARE REfLEcTEd IN ThE mULTIPLE NEW SPEcIES dEScRIPTIONS, NOW cATALOgUEd
AS
ITS SYNONYmS. MOLEcULARLY,
CUNhA
et al
. (2017) fOUNd OUT ThAT
Obelia
dichotoma
IS NOT mONOPhYLETIc ANd mIghT cORRESPONd TO A cOmPLEX Of cRYPTIc SPEcIES.
Distribution.
Obelia
dichotoma
WAS REPORTEd bY FRASER (1938A, b, 1948) fROm ThE MEXIcAN PAcIfIc
AS
dIffERENT SPEcIES, NOWAdAYS cONSIdEREd
AS
ITS SYNONYmS.
AS
fOR
OAXAcA
, IT WAS REPORTEd IN TANgOLUNdA bAY (FRASER 1938A,
AS
Obelia
dichotoma
ANd
Obelia commissuralis
) ANd ChAcAhUA bAY (FRASER 1948). ThIS SPEcIES IS bELIEVEd TO bE cIRcUmgLObAL IN dISTRIbUTION (CALdER 1991; KELmO & ATTRILL 2003; CALdER 2012).