Pennaria disticha Goldfuss, 1820

Humara-Gil, Karla J. & Cruz-Gómez, Christopher, 2018, New records of benthic hydroids (Cnidaria: Hydrozoa) from the coast of Oaxaca, Mexico, Zootaxa 4455 (3), pp. 454-470 : 456

Pennaria disticha Goldfuss, 1820

FIg. 2

Pennaria disticha GOLdfuSS, 1820 : 89.—CALdER et al., 2003: 1198.— SchuchERt, 2006: 364, fIG. 15 (SyN.).—CALdER, 2010: 63, fIG. 43 (SyN.).—MIGLIEttA et al., 2015: 1.—MIGLIEttA et al., 2018: 1.

Pennaria tiarella .—FRASER, 1938A: 25.—FRASER, 1938c: 132.—FRASER, 1948: 200.

Halocordyle disticha .—CALdER, 1988: 56, fIG. 43, 44 (SyN.).—dA SILVEIRA & MIGOttO, 1991: 437, fIG. 1.—KELmO & dE SANtA- ISAbEL, 1998: 68, fIG. 9 (SyN.).

Type locality. GULf Of NAPLES, ITALY (CALdER 1988).

Material examined. EIghT cOLONIES: UMAR-HYDR-001, fOUR cOLONIES ON ROcKS (ESTAcAhUITE BAY, OAXAcA, 15°40’07’’N 96°28’53’’W, 2 m, 11 APRIL 2015, cOLL. J.P. SáNchEZ-OVANdO); UMAR-HYDR-002, fOUR cOLONIES ON ROcKS (AgUETE BAY, OAXAcA, 15°39’52’’N 96°29’06’’W, 1.5 m, 26 APRIL 2015, cOLL. J.P. SáNchEZ-OVANdO).

Description. COLONIES EREcT, 4.8–5.4 cm hIgh, PINNATE; ARISINg fROm A cREEPINg, RAmIfIEd hYdRORhIZA. HYdROcAULUS mONOSIPhONIc ANd cOmPLETELY STRAIghT, bEARINg A TERmINAL hYdRANTh. PERISARc fIRm ANd ThIcK, bROWN AT bASE Of cOLONIES ANd hYdROcLAdIA, gETTINg ThINNER ANd LIghTER AT dISTAL SEcTIONS Of bOTh. ANNULATIONS PRESENT ON hYdROcAULUS AT INSERTION Of EAch bRANch AT REgULAR INTERVALS. HYdROcLAdIA ALTERNATE, UNbRANchEd (WIThOUT SEcONdARY hYdROcLAdIA); EAch ONE PRESENTINg A TERmINAL hYdRANTh. LONgEST hYdROcLAdIA OccURRINg IN mId-REgION Of cOLONIES, WITh ThEIR LENgTh bEINg REdUcEd PROXImALLY ANd dISTALLY. PEdIcELS Of hYdRANThS UNbRANchEd, ANNULATEd AT bASE OR ThROUghOUT, ORIgINATINg ON UPPER SIdE Of hYdROcLAdIA. HYdRANThS PEAR-ShAPEd, AbOUT 1.2 mm LONg, 0.37 mm WIdE; WITh dOmE-ShAPEd hYPOSTOmE, 12–14 fILIfORm TENTAcLES ANd, USUALLY, 16 cAPITATE TENTAcLES. COLONIES WITh ImmATURE gONOPhORES, ALmOST SPhERIcAL, 0.38 mm hIgh, 0.34 mm WIdE; ANd mATURE, ObLONg gONOPhORES, 0.75 mm hIgh, 0.52 WIdE. BOTh TYPES Of gONOPhORES ARISINg fROm A PEdIcEL AbOVE fILIfORm TENTAcLES.

Remarks. ThE mORPhOLOgY Of ThESE SPEcImENS cORRESPONdEd WITh A dEScRIPTION Of P. disticha bY SchUchERT (2006), ALThOUgh NO SEcONdARY hYdROcLAdIA WERE ObSERVEd. EARLIER REcORdS Of ThIS SPEcIES fROm ThE EASTERN PAcIfIc INcLUdE ThOSE Of FRASER (1938A, c, 1948, AS Pennaria tiarella ), CALdER et al. (2003) ANd CALdER (2010); ONLY ThE LATTER INcLUdEd A SPEcIES dEScRIPTION. EXAmINEd cOLONIES dIffEREd fROm ThOSE dEScRIbEd fROm ThE HAWAIIAN ARchIPELAgO bY CALdER (2010) IN SIZE, bEINg UP TO 5.5 TImES ShORTER, ANd IN ThE NUmbER ANd POSITION Of ANNULATIONS ON hYdRANTh PEdIcELS. MORPhOLOgIcAL VARIAbILITY IS KNOWN TO EXIST IN NUmbERS Of fILIfORm ANd cAPITATE TENTAcLES (KELmO & dE SANTA-ISAbEL 1998), NUmbERS Of PERISARc RINgS, RAmIfIcATION Of hYdROcLAdIA, ANd fORm OR SIZE Of ThE cOLONY (dA SILVEIRA & MIgOTTO 1991; SchUchERT 2006). CALdER (1988) ANd dA SILVEIRA & MIgOTTO (1991) ATTRIbUTEd mOdIfIcATIONS IN cOLONY fORm TO ENVIRONmENTAL cONdITIONS, ALThOUgh ThIS hAS bEEN STUdIEd ONLY IN POPULATIONS fROm ThE ATLANTIc cOAST Of AmERIcA. REcENT mOLEcULAR gENETIc ANALYSES Of Pennaria disticha bY MIgLIETTA et al. (2015, 2018) INdIcATE ThAT ThE NAmE REfERS TO SEVERAL dIffERENT SPEcIES ThAT ARE mORPhOLOgIcALLY dIffIcULT TO dISTINgUISh.

Distribution. Pennaria disticha IS gENERALLY REgARdEd AS A cOSmOPOLITAN IN WARm TEmPERATE TO TROPIcAL WATERS (CALdER 1988; SchUchERT 2006). HOWEVER, mOLEcULAR STUdIES SUggEST ThAT ThIS SPEcIES ShOULd bE cONSIdEREd AS A cRYPTIc SPEcIES cOmPLEX (MIgLIETTA et al. 2015, 2018). ThIS IS ThE fIRST REcORd Of ThE SPEcIES fROm ThE MEXIcAN PAcIfIc.

Figures

FIGURE 2. Pennaria disticha GOLdfuSS, 1820. A, cOLONy; B, hydROcAuLuS wIth tERmINAL hydRANth; C, hydRANth wIth AN ImmAtuRE GONOphORE; D, dEtAIL Of thE hypOStOmE; E, hydRANth wIth A mAtuRE GONOphORE. ScALE bARS: 100 µm (D), 500 µm (B, C, E), 1 cm (A).