Tridentata turbinata ( Lamouroux, 1816 )

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 : 465-467

Tridentata turbinata ( Lamouroux, 1816)

FIg. 8

Dynamena turbinata LAmOuROux, 1816: 180.

Sertularia turbinata .—VERVOORt, 1968: 52, fIG. 25 (SyN.).— MILLARd, 1975: 312, fIG. 100B, C, E (SyN.).—MEdEL & VERVOORt, 1998: 70, fIG. 23 (SyN.).— SchuchERt, 2003: 190, fIG. 44 (SyN.).

Tridentata turbinata .—CALdER, 1991: 110, fIG. 60 (SyN.).—CALdER et al., 2003: 1194, fIG. 16 (SyN.).—CALdER, 2013: 33, fIG. 9G.—MARONNA et al., 2016: 16.

Type locality. AUSTRALASIA ( SchUchERT 2003).

Material examined. TWELVE cOLONIES: UMAR-HYDR-011, SIX cOLONIES ON Amathia SP. (PUERTO ÁNgEL, OAXAcA, 15°39’55’’N 96°29’28’’W, 1.5 m, 11 APRIL 2015, cOLL. C. CRUZ-GómEZ); UMAR-HYDR-012, SIX cOLONIES ON SERPULId Spirobranchus incrassatus TUbES (PUERTO ÁNgEL, OAXAcA, 15°39’55’’N 96°29’28’’W, 2 m, 5 DEcEmbER 2015, cOLL. C. CRUZ-GómEZ ANd J.P. SáNchEZ-OVANdO).

Description. COLONIES EREcT, 0.7–1.3 cm hIgh, ARISINg fROm A cREEPINg STOLON. HYdROcAULUS mONOSIPhONIc, STRAIghT, UNbRANchEd; dIVIdEd INTO INTERNOdES bY TRANSVERSE, dISTINcT NOdES. BASAL PORTION Of hYdROcAULUS WITh AT LEAST ONE AThEcATE INTERNOdE. ThEcATE INTERNOdES WITh OPPOSEd, AdjAcENT hYdROThEcAE NEAR dISTAL ENd. PERISARc ThIcK, TRANSLUcENT. HYdROThEcAE AdNATE fOR AbOUT ½ Of ThEIR AdcAULINE LENgTh, TILTEd TOWARdS AbcAULINE SIdE; AdcAULINE SIdE cURVEd fOR APPROXImATELY 70°, fREE AdcAULINE WALL SLIghTLY dIAgONAL OR cOmPLETELY hORIZONTAL. AbcAULINE WALL AbOUT 210 µm; AdcAULINE WALL AdNATE TO hYdROcAULUS 200 µm, 240 µm fREE. HYdROThEcAL mARgIN WITh TWO LARgE LATERAL cUSPS, A SmALL mEdIAN AdcAULINE cUSP, ANd AN INTRAThEcAL RIdgE; OPERcULUm Of TWO VALVES, WITh AdcAULINE SmALLER ThAN AbcAULINE. GONOThEcAE bARREL-ShAPEd, 870 µm LONg, 650 µm WIdE AT mIddLE, WITh 7–8 EXTERNAL RINgS ANd dISTAL APERTURE; ThESE OccURRINg IN ThE mIddLE OR mORE cOmmONLY AT bASE Of STEm.

Remarks. ThIS SPEcIES hAS OfTEN bEEN ASSIgNEd TO Sertularia LINNAEUS, 1758 INSTEAd Of Tridentata STEchOW, 1920, ALThOUgh SIgNIfIcANT dIffERENcES bETWEEN ThE TWO gENERA ARE EVIdENT mORPhOLOgIcALLY (SEE CALdER 1991: 104). IN AddITION, ThE RESULTS PROVIdEd bY REcENT mOLEcULAR STUdIES (MARONNA et al. 2016) INdIcATE ThAT ThERE mAY bE dIffERENcES bETWEEN Sertularia ANd Tridentata . HOWEVER, ThE AUThORS STATE ThAT mAjOR REVISION IS NEcESSARY TO ESTAbLISh WITh cERTAINTY ThOSE dIffERENcES.

Tridentata turbinata cAN bE cONfUSEd WITh T. borneensis (BILLARd, 1925) bEcAUSE Of SImILARITIES IN ThEIR TROPhOSOmES ( SchUchERT 2003). IN cOLONIES fROm OAXAcA, hYdROThEcAL PAIRS WERE ALWAYS AdjAcENT ANd AN INTRAThEcAL RIdgE WAS PRESENT, UNIqUE fEATURES Of ThE fORmER SPEcIES. ThE INTRAThEcAL RIdgE WAS LESS cONSPIcUOUS ON dISTAL hYdROThEcAE, PERhAPS bEcAUSE APIcAL hYdRANThS WERE YOUNgER. GONOThEcAE Of ThE SPEcIES ARE RARELY REPORTEd (VERVOORT 1968; MEdEL & VERVOORT 1998; SchUchERT 2003; CALdER et al. 2003; CALdER 2013), bUT ThEY WERE PRESENT IN OUR mATERIAL. COmPAREd TO ThE gONOThEcA Of T. borneensis , AS dEScRIbEd bY SchUchERT (2003), ThE cURVES ON ThE gONOThEcAL mARgIN Of T. turbinata WERE LESS PRONOUNcEd ANd ITS dIAmETER WAS bROAdER. ITS ShAPE cOINcIdES WITh ThE dEScRIPTION bY MILLARd (1975).

Distribution. ThIS SPEcIES IS WIdELY dISTRIbUTEd IN TROPIcAL ANd SUbTROPIcAL WATERS ( SchUchERT 2003, AS Sertularia turbinata ). ThIS IS ThE fIRST REcORd Of ThE SPEcIES fOR ThE MEXIcAN PAcIfIc.

Figures

FIGURE 8. Tridentata turbinata (LAmOuROux, 1816). A, cOLONy; B, E, GONOthEcAE; C, D, uppER hydRANthS, in vivo ANd fIxEd zOOIdS. ScALE bARS: 500 µm (C‒E), 1 mm (B), 5 mm (A).