MARINE AND FISHERY SCIENCES 37 (1): 27-39 (2024)

https://doi.org/10.47193/mafis.3712024010104

ABSTRACT. Two species of Hydractiniidae (Hydrozoa) with metagenetic life cycle have been

recorded for the temperate region of the southwestern Atlantic Ocean: the medusa stage of Podoco-

ryna tenuis and the polyp stage of P. humilis. Both the adult medusa of P. humilis and the polyp stage

of P. tenuis are unknown, but it is possible that they are different stages of the same species, a

hypothesis still to be tested. Colonies of P. humilis growing on the southern king crab Lithodes san-

tolla collected at the Atlantic Patagonian coast, and two small medusae released from these hydroid

colonies were analyzed. Medusa of P. humilis were kept alive for 3 days and they were morpholog-

ically compared with the medusae of P. tenuis sorted out from ~2,500 plankton samples along the

Atlantic Patagonian coast. The study of these specimens allowed reassessing the taxonomic status

of P. humilis and P. tenuis from the southwestern Atlantic Ocean. Polyp and young medusa stages

of P. humilis were described, and additional information was recovered to better describe the

medusa stage of P. tenuis. New morphologic and biogeographic evidences in order to propose the

synonymy between P. tenuis and P. humilis were discussed.

Key words: Hydroids, Hydromedusae, Hydractiniidae, Patagonia.

Podocoryna tenuis (Hydrozoa) en aguas templadas del Atlántico Sudoccidental: datos adi-

cionales sobre las etapas del ciclo de vida respaldan su sinónimo con Podocoryna humilis

RESUMEN. Se han registrado dos especies de Hydractiniidae (Hydrozoa) con ciclo de vida

metagenético para la región templada del suroeste del Océano Atlántico: la etapa de medusa de

Podocoryna tenuis y la etapa de pólipo de P. humilis. Tanto la medusa adulta de P. humilis como el

estadio de pólipo de P. tenuis son desconocidos, pero es posible que se trate de diferentes estadios

de una misma especie, hipótesis aún por contrastar. Se analizaron colonias de P. humilis que crecían

sobre la centolla Lithodes santolla recolectadas en la costa atlántica de la Patagonia, y dos pequeñas

medusas liberadas de estas colonias de hidroides. Las medusas de P. humilis se mantuvieron vivas

durante 3 días y se compararon morfológicamente con las medusas de P. tenuis seleccionadas de

~2.500 muestras de plancton a lo largo de la costa atlántica patagónica. El estudio de estos especí-

menes nos permitió reevaluar el estado taxonómico de P. humilis y P. tenuis del Océano Atlántico

Sudoccidental. Se describen las etapas de pólipo y medusa joven de P. humilis, y se recuperó infor-

mación adicional para describir mejor la etapa de medusa de P. tenuis. Se discuten las nuevas evi-

dencias morfológicas y biogeográficas para proponer la sinonimia entre P. tenuis y P. humilis.

Palabras clave: Hydroides, Hydromedusae, Hydractiniidae, Patagonia.

27

*Correspondence:

genzanogabriel@gmail.com

Received: 12 June 2023

Accepted: 31 July 2023

ISSN 2683-7595 (print)

ISSN 2683-7951 (online)

https://ojs.inidep.edu.ar

Journal of the Instituto Nacional de

Investigación y Desarrollo Pesquero

(INIDEP)

This work is licensed under a Creative

Commons Attribution-

NonCommercial-ShareAlike 4.0

International License

Marine and

Fishery Sciences

MAFIS

ORIGINAL RESEARCH

Podocoryna tenuis (Hydrozoa) in temperate waters of the southwestern

Atlantic: additional data on life cycle stages support its synonym with

Podocoryna humilis

GABRIEL N. GENZANO1, 2, *, THAÍS P. MIRANDA3, NURIA VÁZQUEZ4, JULIETA JAÑEZ5and ANTONIO C. MARQUES3, 6

1Instituto de Investigaciones Marinas y Costeras (IIMyC), Universidad Nacional de Mar del Plata (UNMDP), Consejo Nacional de

Investigaciones Científicas y Técnicas (CONICET), Mar del Plata, Argentina. 2Consejo Nacional de Investigaciones Científicas y Técnicas

(CONICET), Argentina. 3Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua Matão Trav. 14, 101,

05508-090 - São Paulo, Brazil. 4Laboratorio de Parasitología, Instituto de Biología de Organismos Marinos (IBIOMAR-CONICET),

Boulevard Brown 2915, U9120ACD - Puerto Madryn, Argentina. 5Fundación Temaiken, Acuario, Ruta Provincial 25, km 1, 1625 - Escobar, ,

Argentina. 6Centro de Biologia Marinha, Universidade de São Paulo, Rodovia Doutor Manoel Hipólito do Rego, km 131,5, 11612-109 - São

Sebastião, Brazil. ORCID Gabriel N. Genzano https://orcid.org/0000-0002-9818-7648

INTRODUCTION

Species of the Family Hydractiniidae L. Agas-

siz, 1862 (Cnidaria, Hydrozoa) are recorded

worldwide on different substrates, such as algae,

barnacles, rock, and even fishes, but they are usu-

ally found encrusting gastropod shells which can

be occupied by hermit crabs (Miglietta and Cun-

ningham 2012).

The metagenetic life cycle, involving planula,

benthic asexual polyp, and swimming sexual

medusa, occurs in some species (Bouillon et al.

2006), but many hydractiniid species have differ-

ent stages of reduction of the swimming medusa,

either to ephemeral medusoids or to sporosacs

(Miglietta and Cunningham 2012).

The most speciose genera of Hydractiniidae,

viz., Hydractinia van Beneden 1844, Podocoryna

M. Sars 1846, and Stylactis Allman, 1864, have

been historically distinguished by a few characters,

such as expression of the sexual stage (i.e.

medusa/medusoid/gonophore) and morphology of

the hydrorhiza (e.g.reticular or encrusting mat

with or without perisarc, and chitinous or calcare-

ous spines) (Schuchert 2008). These characters,

however, are plastic and have intergrading mor-

phologies among species and genera (Calder 1988;

Bouillon et al. 1997), being either incongruent

(e.g. hydrorhizal morphology) or partially congru-

ent with phylogenetic patterns (Miglietta and Cun-

ningham 2012). The scarcity of knowledge on

many life cycle strategies of hydractiniids also col-

laborates to make its taxonomy poorly understood.

Three species of Hydractiniidae have been

recorded for the temperate region of the south-

western Atlantic Ocean: Hydractinia parvispina

Hartlaub, 1905, Podocoryna humilis (Hartlaub,

1905) and Podocoryna tenuis (Browne, 1902)

(see synthesis in Oliveira et al. 2016). Browne

(1902) described Dysmorphosa tenuis, currently

accepted as Podocoryna tenuis, based on two

medusae from Malvinas Islands, and this species

was subsequently also reported for the southern

Patagonian coast (Genzano et al. 2008). Hartlaub

(1905) described two hydractiniid species from

Tierra del Fuego based on the polyp stage:

Hydractinia parvispina (with sporosacs) and P.

humilis (with medusa buds), the latter originally

described in the Genus Podocoryne Luetken,

1850. Both the adult medusa of P. humilis and the

polyp stage of P. tenuis are unknown. Hartlaub

(1905) was the first author to suggest that P.

humilis could be the polyp stage of P. tenuis, a

hypothesis still in need to be tested (Galea 2007).

We came across with colonies assignable to P.

humilis growing on the southern king crab Lith-

odes santolla (Molina, 1782) from the Patagonian

coast. Some colonies were kept in aquarium and

released two small medusae that were kept alive

for 3 days. This material was compared with

medusae of P. tenuis from the Atlantic Patagonian

coast. Morphological and morphometric analyses

of P. humilis and P. tenuis allowed us to reassess

the taxonomic status of these two hydractiniid

species for the southwestern Atlantic Ocean.

Here, the polyp and the young medusa stages of

P. humilis were described, and descriptions of the

medusa stage of P. tenuis were complemented.

We aimed to provide additional data and new

arguments to support the synonymy of P. tenuis

and P. humilis.

MATERIAL AND METHODS

Three specimens of king crab Lithodes santol-

la with epizoic hydractiniid colonies were col-

lected in October 2014, January 2015 and Febru-

ary 2016, respectively, at 35-40 m depth along the

southern zone of San Jorge Gulf, Comodoro

Rivadavia, Argentina (~45.87° S-66.38° W)

(Figure 1). Samples were fixed in 5% formalde-

hyde solution diluted in seawater and transferred

to 96-100% ethanol (FCEyN-UNMdP Hd 9-80;

Hd 11-115; MZUSP 3411, 3412, 3413, 3414).

28 MARINE AND FISHERY SCIENCES 37 (1): 27-39 (2024)

One epizoic colony from San Jorge Gulf was

observed in vivo in November 2006 and two

medusae were released and kept alive for 3 days,

being subsequently preserved in 5% formalde-

hyde. This material was compared with P. tenuis

medusae collected in December 1996 (N =1) and

December 2006 (N =1) at 54.91° S-55.10° S and

66.50° W-68.20° W (FCEyN-UNMdP Hm 11-6,

Hm 11-7), respectively, using Pairovet plankton

net (mesh size 200 mm), and at 41.33° S-41.48° S,

64.83° W-64.91° W (N =1) (FCEyN-UNMdP

Hm 11-8), using Bongo plankton net (mesh size

300 mm). All planktonic samples were fixed in

5% formaldehyde solution.

Photos in aquarium of one colony growing on

red king crab L. santolla and one medusa released

from it (August 2020), and also photos in nature

of two colonies attached to two tractor crabs

Peltarion spinulosum (White, 1843), both from

Beagle Channel, Tierra del Fuego (54° 48' S-68°

18'W) provided additional information.

All specimens were morphologically and mor-

phometrically analyzed under stereo and com-

pound light microscope. Specimens were identi-

fied to the species level based on specific litera-

ture (e.g. Hartlaub 1905; Browne and Kramp

1939; Kramp 1952; Schuchert 2001, 2008; Galea

2007). The current classification for the genera of

Hydractiniidae (Miglietta and Cunningham 2012)

was adopted. Cnidome was identified according

to Mariscal (1974) and Millard (1975). Speci-

mens are deposited in the Invertebrate Collection

of the Departamento de Ciencias Marinas, Facul-

tad de Ciencias Exactas y Naturales, Universidad

Nacional de Mar del Plata (FCEyN-UNMdP),

and in the Collection of Marine Invertebrates of

the Museu de Zoologia, Universidade de São

Paulo (MZUSP).

RESULTS

Polyp stage

Material examined

Two colonies on two individuals of L. santolla,

San Jorge Gulf, 45.87° S-66.38° W, 35-40 m

depth, October 2014, formaldehyde 5%; one

colony on one individual of L. santolla, 45.87° S-

66.38° W, 35-40 m depth, January 2015, ethanol

96%; two colonies on two individuals of L. san-

tolla, 45.87° S-66.38° W, 35-40 m depth, Febru-

ary 2016, formaldehyde 5% and ethanol 96%.

Description

Colonies grouped on inferior and superior cara-

pace, chelae and walking legs of L. santolla (Fig-

29

GENZANO ET AL.: PODOCORYNA TENUIS (HYDROZOA) IN TEMPERATE WATERS OF SOUTHWESTERN ATLANTIC

Figure 1. Sampling locations of Podocoryna tenuis along the

Atlantic Patagonian coast. Encircled black dots indi-

cate stations where medusae were collected by

plankton tows. Star indicates the location where the

southern king crab Lithodes santolla where collected

with the epizoic Hydractiniidae colonies. Empty star

indicates the location where a tractor crab Peltarion

spinulosum with epizoic colonies was photographed.

Southwestern

Atlantic Ocean

Argentina

San

Matías Gulf

San

Jorge Gulf

Tierra del Fuego

100 m 200 m

Banco Burdwood N

S

35°

40°

45°

50°

55°

W65° 60° 55° 50°

ure 2 A and 2 B). Hydrorhiza creeping and stolon-

al, without calcareous spines. Polyps without cal-

careous skeleton, polymorphic (gastrozooids and

gonozooids) arising directly from hydrorhiza.

Gastrozooids club-shaped, 2.9-4.3 mm high, 0.2-

0.5 mm wide (n =30); hypostome dome-shaped,

with one whorl of 5-15 filiform tentacles (Figure

3 A and 3 B). Gonozooids 4.4-5.5 mm high, 0.2-

0.4 mm wide (n =30); gonophores branched pro-

ducing free medusae, arranged in clusters of 3-32

globular to oblong medusa buds, arising along the

distal half of gonozooid (Figure 3 C-F); medusa

buds 0.22-0.49 mm high, 0.19-0.35 mm wide,

with 4 radial canals and 4 tentacular bulbs; some

individuals with 4 tentacles and manubrium as

ovoid mass without mouth (Figure 2 C and 2 D).

Nematocysts microbasic mastigophores, length 7-

9 mm, width 2-3 mm.

Remarks

Polyps stage are similar to Podocoryna humilis

Hartlaub, 1905, except for the presence of spines

on hydrorhiza (absent in our preserved material).

This character, however, seems to be variable,

since small spines were observed in colonies

growing on one specimen (not preserved) of L.

santolla from Tierra del Fuego (see discussion

below).

Young medusa stage

Material examined

Two medusae released from colonies growing

on one king crab L. santolla, November 2006,

45.87° S-66.38° W, and kept alive in aquarium

for 3 days, being subsequently preserved in 5%

formaldehyde.

30 MARINE AND FISHERY SCIENCES 37 (1): 27-39 (2024)

Figure 2. Lithodes santolla with epizoic colonies of Podocoryna tenuis. A) Southern king crab with colonies on the ventral cara-

pace and on the left walking leg. B) Detail of the walking leg with colonies of P. tenuis. C) Colony of P. tenuis with a

recent released medusa. D) Detail of the recent released medusa of P. tenuis. Scales: a and b: 3 cm; c: 500 mm; d: 100 mm.

A

B

C

D

Description

Newly-released medusa measuring 0.3 mm in

diameter, 0.4 mm height, 4 large perradial mar-

ginal bulbs with tentacles; interradial bulbs

absent; manubrium simple, cubical. Three-days

old medusae with 0.5-0.6 mm in diameter, 0,7

mm height, 4 perradial tentacles, 2-4 interradial

shorter tentacles, inconspicuous interradial ten-

tacular bulbs, manubrium extending up to the half

of the subumbrellar height, with small terminal

clusters of cnidocysts; gonads absent (Figure 3 G

and 3 H).

Remarks

The young medusae resembles Hydractinia

tenuis (Browne, 1902). Browne and Kramp

(1939) described for this region juveniles of H.

tenuis morphologically similar to analyzed speci-

mens, having mouth with four lips and terminal

clusters of nematocyst, eight marginal tentacles

and absence of medusa buds upon the stomach, in

specimens smaller than 1 mm.

Medusa stage

Material examined

One medusa, 54.91° S-66.50° W, December

1996, formaldehyde 5%; one medusa, 55.10° S-

68.20° W, December 1996, formaldehyde 5%;

one medusa, 41.33° S-64.52° W, December,

2006, formaldehyde 5%.

Description

Medusa collected from water column were

0.65-1.30 mm high, slightly wider than tall (width

0.75-1.50 mm), with gastric peduncle; manubrium

extends up to 2/3 of subumbrellar height, cubical,

with 4 perradial short simple lips; terminal cluster

of cnidocysts at the end of each lip; specimens

from San Matias Gulf with short and slightly

branched lips. Four broad radial canals, 8 tenta-

cles, perradial and interradial bulbs without ocelli.

Gonads not developed. Two specimens with 0.10-

0.15 mm high medusae buds on the manubrium,

in different developmental stages (Figure 4 A-D).

31

GENZANO ET AL.: PODOCORYNA TENUIS (HYDROZOA) IN TEMPERATE WATERS OF SOUTHWESTERN ATLANTIC

Figure 3. Preserved material of medusa and polyp stages of Podocoryna tenuis collected from San Jorge Gulf. A) Gastrozooid.

B) Oral region of the gastrozooid. C and D) Gonozooids. E and F). Detail of medusa buds. G and H) Two days old

medusae. Scales: a, c-f: 1 mm; b: 200 mm; g and h: 500 mm.

AB CD

EF GH

Remarks

Morphological characters and measurement of

medusa specimens analyzed in this study corre-

sponded to the description of H. tenuis (Browne,

1902).In addition, the presence of medusa buds

upon the stomach, interradially situated, agree

with those described for this species.

Taxonomy

Polyps and medusa stages of Podocoryna

/Hydractinia from temperate waters of south-

western Atlantic were separately described

almost one century ago. Considering the morpho-

logical similitudes found between the analyzed

material and that early description of both stages

and, additional data on life cycle phases the fol-

lowing synonyms is adopted.

Class Hydrozoa Owen, 1843

Subclass Hydroidolina Collins, 2000

Superorder Anthoathecata Cornelius, 1992

–non-monophyletic

Order Filifera Kühn, 1913 –non-monophyletic

Family Hydractiniidae L. Agassiz, 1862

Genus Podocoryna M. Sars, 1846

Podocoryna tenuis (Browne, 1902)

Figures 2-5

Dysmorphosa tenuis Browne, 1902 p. 277

[medusa].

Podocoryne humilis Hartlaub, 1905 p. 523-524;

Genzano and Zamponi 1997 p. 289 [polyp].

Podocoryne tenuis—Mayer 1910b p. 141;

Browne and Kramp 1939 p. 280-281, pl. 15

fig. 5-6; Kramp 1959 p. 102 fig. 70; Kramp

1961 p. 70 [medusa].

Podocoryna carnea var. chilensis Kramp, 1952 p.

4-6, figs 1-2 [polyp and medusa] [non Podoco-

ryna carnea M. Sars, 1846].

Podocoryne carnea—Segura-Puertas 1984 p. 26,

pl. 4, fig. 1 [medusa] [non Podocoryna carnea

M. Sars, 1846].

Hydractinia tenuis—Galea 2007 p. 25, pl. 1H,

fig. 6L; Palma et al. 2011 p. 263, 269; Genzano

et al. 2008 p. 8; Villenas et al. 2009 p. 313,

318, 321-322.

Podocoryne minuta—Pagès and Orejas 1999 p.

53, 56 [medusa] [non Dysmorphosa (Hydrac-

tinia) minuta Mayer, 1900].

Hydractinia minuta—Tronolone 2001 p. 60-62,

fig. 14a-c; Migotto et al. 2002 p. 12; Palma et

al. 2007a p. 74, 78, 81, 2007b p. 69-71, 73-74;

Villenas et al. 2009 p. 318; Bravo et al. 2011 p.

[medusa].

32 MARINE AND FISHERY SCIENCES 37 (1): 27-39 (2024)

Figure 4. Preserved material of adult medusa stage of Podocoryna tenuis collected from San Matías Gulf and detail of slightly

branched lips (A). Specimen from Tierra del Fuego with medusa bud on the manubrium (B and C) and detail lips with

terminal cluster of cnidocyts (D). Scales: a: 200 mm; b-d: 100 mm.

AC

D

B

DISCUSSION

Morphological characters of Patagonian

medusae herein studied corresponded to the

description of P. tenuis, a species originally

recorded for Malvinas Islands and commonly

found in South American waters (Oliveira et al.

2016, for a review). Patagonian polyps, however,

are morphologically similar to P. humilis original-

ly recorded for Tierra del Fuego. Curiously, since

its original description, Hartlaub (1905) already

hypothesized that his species could be the polyp

stage of P. tenuis. Posteriorly, Mayer (1910) also

considered this idea, but it could be inferred that

the lack of newly released medusae has prevented

him to assume the synonymy.

Podocoryna carnea (M. Sars, 1846) is a well-

known northern hemisphere species, also

accounting with doubtful records at the southern

hemisphere (Edwards 1972; Schuchert 2008).

South American specimens assigned to P. carnea

were described from Chile (Kramp 1952,

colonies and newly released medusae for Puerto

Montt) and Peru (Segura-Puertas 1984, one

medusa only). Immature medusae described can-

not be conclusively assigned to P. carnea.

Colonies described for Chile also have taxonom-

ical uncertainties. They were doubtfully de-

scribed as P. carnea var. chilensis by Kramp

(1952), but they differ from north European P.

carnea by lacking spines, spiral zooids or tentac-

ulozooids (Schuchert 2001). These characters,

however, are considered variable, e.g. spines have

variable density and would be often absent

depending on the host and habitat inhabited by

the colony (Edwards 1972; Calder 1988;

Schuchert 2008). Additionally, spiral zooids or

tentaculozooids are only present in epizoic

colonies on hermit crabs (Schuchert 2008).

On the other hand, Chilean and Peruvian

immature medusa assigned to P. carnea are simi-

lar to the Patagonian material we have studied,

differing only by the timing of appearance of

interradial bulbs (Kramp 1952; Segura-Puertas

1984). Chilean colonies are especially similar to

Patagonian ones in the lack of spines, spiral and

tentaculozooids, differing only by slightly small-

er dimensions and number of gastrozooid tenta-

cles. Both of these morphological characters,

however, are highly variable for species differen-

tiation.

Seventeen species assigned to Hydractiniidae

were so far recorded for the South American

coast, either with the medusa stage or with fixed

gonophores: 10 of them are exclusively distrib-

uted along the Pacific side, 4 are exclusive on the

Atlantic side, and 3 are distributed along both

oceans of South American coast (Oliveira et al.

2016). Except for P. carnea (already discussed

above), we focused our comparisons among the

six species with free-swimming medusa stages

(i.e. Podocoryna spp.) in order to clarify their

morphological differences in relation to P. tenuis

(and also P. humilis) (Table 1).

Three species of Podocoryna have only the

medusa stage recorded for South America:

Podocoryna apicata (Kramp, 1959), Podocoryna

areolata (Alder, 1862) and Podocoryna borealis

(Mayer, 1900) (Table 1). The medusa stage of P.

apicata differs from P. tenuis by the apical

process and thick mesoglea (Segura-Puertas

1984). P. areolata and P. borealis have the

medusa stage described for elsewhere (Edwards

1972; Schuchert 2001, 2008). The main differ-

ences between P. areolata and P. tenuis medusae

are related with the thickening of the mesoglea at

the apex, the high number of tentacles (~40 to

56) and the spanning of the manubrium at ca. 1/2

of the subumbrella height (Schuchert 2008).

Colonies of P. borealis have the polyp stage also

described for elsewhere, differing from P. tenuis

by the presence of spines and tentaculozooids

(Edwards 1972; Schuchert 2001). The young

medusa stage of P. borealis is larger (~0.8 mm)

than P. tenuis and has 6-8 tentacles (Schuchert

2001).

33

GENZANO ET AL.: PODOCORYNA TENUIS (HYDROZOA) IN TEMPERATE WATERS OF SOUTHWESTERN ATLANTIC

34 MARINE AND FISHERY SCIENCES 37 (1): 27-39 (2024)

Table 1. Species of Hydractiniidae recorded for the South American coast. Data of Podocoryna tenuis reported in this study. P =

polyp; M =medusa; FS =fixed gonophores.

Species Recorded Reproductive Atlantic Pacific References

stage stage

Hydractinia echinata P FS + Wedler (1975), Oliveira et al. (2016)

(Fleming, 1828)

Hydractinia hancocki P FS + Fraser (1938a); Calder et al. (2003);

Fraser, 1938 Oliveira et al. (2016)

Hydractinia longispina P FS + Fraser (1938a, 1938b, 1939, 1948);

Fraser, 1938 Calder et al. (2003); Oliveira et al. (2016)

Hydractinia multispina P FS + Fraser (1938a, 1938b, 1948); Calder

Fraser, 1938 et al. (2003); Oliveira et al. (2016)

Hydractinia pacifica P FS + Hatlaub (1905); Galea (2007); Galea et al.

Hartlaub, 1905 (2007, 2009); Galea and Schories (2012)

Hydractinia parvispina P FS + + Hartlaub (1905); Jäderholm (1905, 1917);

Hartlaub, 1905 Blanco (1994); Genzano and Zamponi

(1997); Oliveira et al. (2016)

Hydractinia polycarpa P FS + Fraser (1938a, 1948); Oliveira et al. (2016)

Fraser, 1938

Hydractinia rugosa P FS + Fraser (1938b, 1948)

Fraser, 1938

Podocoryna apicata M M + Segura-Puertas (1984); Oliveira et al.

(Kramp, 1959) (2016)

Podocoryna areolata M M + Guerrero et al. (2013); Oliveira et al.

(Alder, 1862) (2016)

Podocoryna borealis M M + Pagès and Orejas (1999); Galea (2007);

(Mayer, 1900) Galea et al. (2007); Palma et al. (2007a,

2007b, 2011); Villenas et al. (2009);

Bravo et al. (2011); Oliveira et al. (2016)

Podocoryna carnea P, M M + Kramp (1952); Segura-Puertas (1984);

(M. Sars, 1846) Oliveira et al. (2016)

Podocoryna humilis P, M(?) M + + Hartlaub (1905); Blanco (1994); Genzano

(Hartlaub, 1905) and Zamponi (1997); Oliveira et al.

(2016)

Podocoryna loyola P, M M + Correia (1983); Bettim and Haddad

Haddad, Bettim and (2013); Haddad et al. (2014); Nogueira

Miglietta, 2014 Jr et al. (2015); Oliveira et al. (2016)

Podocoryna quitus P, M(?) M + Fraser (1938a, 1948); Oliveira et al. (2016)

Miranda and

Marques, 2016

The other three South American Podocoryna

species, i.e. P. loyola, P. quitus, and P. uniformis,

have both polyp and medusa stages recorded for

the region (Table 1), although only medusa buds

were observed for P. quitus (Fraser 1938a, p. 24-

25, fig. 23C). All of them are also clearly different

from P. tenuis and P. humilis. Colonies of P. loyola

have tentaculozooids, newly-liberated medusae

with eight tentacular bulbs, eight tentacles, and

small interradial gonads (Haddad et al. 2014).

Colonies of P. quitus have very small gastrozooids

(up to 0.7 mm) and medusa buds arising right

below tentacles, and occasionally, directly from

the stolon (Fraser 1938b). Colonies of P. uniformis

have monomorphic polyps with nipple-shaped

hypostome and red ocelli in marginal bulbs of

newly-released medusa (Stampar et al. 2006).

Many hydroids are generalists in the use of sub-

strata, with specializations rarely observed in a

few taxa (Campos et al. 2012; Miglietta and Cun-

ningham 2012). Species of the Family Hydractini-

idae usually grow on mollusk shells, especially

those inhabiting hermit crabs, but they also occur

on other moving and non-moving substrata

(Schuchert 2008; Miglietta et al. 2009). Colonies

of P. tenuis were previously recorded on gas-

tropods (Hartlaub 1905), and herein recorded on

the southern red crab L. santolla but also on cara-

pace, chelae and walking legs of tractor crab, P.

spinulosum (Figure 5). The inconspicuousness of

colonies may be one of the reasons for the few

data of these organisms, making them incorrectly

interpreted as rare species.

Specimens of Podocoryna herein studied sug-

gest that polyps of P. humilis and medusae of P.

tenuis are the same species. Historical biogeo-

graphic records of both P. humilis (Hartlaub 1905)

and P. tenuis (Browne 1902) exclusively along the

South America coast reinforce this. Furthermore,

the lack of additional records of P. humilis for

more than one century of marine research along

the South American coast is another putative evi-

dence that Hartlaub’s specimens might refer to P.

tenuis (Browne 1902). We are aware, however,

that molecular techniques are fundamental to help

clarifying this taxonomic question in the near

future, including the phylogenetic position of

these species in the Family Hydractiniidae.

35

GENZANO ET AL.: PODOCORYNA TENUIS (HYDROZOA) IN TEMPERATE WATERS OF SOUTHWESTERN ATLANTIC

Table 1. Continued.

Species Recorded Reproductive Atlantic Pacific References

stage stage

Podocoryna tenuis P, M M + + Browne (1902); Browne and Kramp (1939);

Hartlaub, 1905 Hartlaub (1905); Kramp (1952); Segura-

Puertas (1984); Blanco (1994); Genzano

and Zamponi (1997); Pagès and Orejas

(1999); Tronolone (2001); Migotto et al.

(2002); Galea (2007); Genzano et al.

(2008); Villenas et al. (2009); Bravo et al.

(2011); Silveira and Morandini (2011);

Oliveira et al. (2016)

Podocoryna uniformis P, M M + Stampar et al. (2006b); Miranda et al.

(Stampar, Tronolone (2015); Oliveira et al. (2016)

and Morandini, 2006)

ACKNOWLEDGMENTS

The present study was partially funded by

EXA 1038/21 (UNMdP) and by São Paulo

Research Foundation-FAPESP (ACM grant

2011/50242-5, 2013/50484-4; TPM grant 2014/

24407-5), and CNPq (ACM grants 477156/2011-

8, 305805/2013-4, 445444/2014-2). Thanks are

due to Mariano Rodríguez, @argentinasubmari-

na, and Paula Sotelano, Laboratorio de Crustá-

ceos y Ecosistemas costeros (CADIC-CONICET)

for providing us with photos of P. tenuis on P.

spinulosum and L. santolla, respectively.

Author contributions

Gabriel N. Genzano: investigation, conceptual-

ization, funding acquisition, formal analysis,

methodology, writing-original draft, writing-

review and editing. Thaís P. Miranda: conceptual-

ization, supervision, writing-review and editing.

Nuria Vázquez: data curation. Resources-provi-

36 MARINE AND FISHERY SCIENCES 37 (1): 27-39 (2024)

sion of study materials. Julieta Jañez: data cura-

tion, resources-provision of study materials. Anto-

nio C. Marques: funding acquisition, writing-

review and editing.

REFERENCES

BETTIM AL, HADDAD MA. 2013. First record of

endoparasitism of Pycnogonida in Hydrozoan

polyps (Cnidaria) from the Brazilian coast.

Biota Neotrop. 13: 319-325.

BLANCO OM. 1994. Enumeración sistemática y

distribución geográfica preliminar de los

hidroides de la República Argentina, Suborden

Athecata (Gymnoblastea, Anthomedusae),

Thecata (Calyptoblastea, Leptomedusae) y

Limnomedusae. Rev Museo La Plata (Nueva

Ser) (Zool). 14: 181-216.

BOUILLON J, GRAVILI C, PAGÈS F, GILI J-M, BOERO

F. 2006. An introduction to Hydrozoa.

Mémoires du Muséum national d’Histoire

naturelle. 194. Paris: Publications Scientifi-

ques du Muséu. 591 p.

Figure 5. Tractor crabs Peltarion spinulosum with detail of epizoic colonies.

BOUILLON J, MEDEL D, PEÑA CANTERO AL. 1997.

The taxonomic status of the genus Stylactaria

Stechow, 1921 (Hydroidomedusae, Anthome-

dusae, Hydractiniidae), with the description of a

new species. Sci Mar. 61: 471-486.

BRAVO V, PALMA S, SILVA N. 2011. Seasonal and

vertical distribution of medusae in Aysén

region, southern Chile. Lat Am J Aquat Res.

39: 359-377.

BROWNE ET. 1902. A preliminary report on

hydromedusae from the Falkland Islands. Ann

Mag Nat Hist. 9: 272-284.

BROWNE ET, KRAMP PL. 1939. Hydromedusae

from the Falkland Islands. Discovery Reports.

18: 265-322.

CALDER DR. 1988. Shallow-water hydroids of

Bermuda: the Athecatae. Life Sci Contrib R

Ont Mus. 148: 1-107.

CALDER DR, MALLINSON JJ, COLLINS K, HICK-

MAN CP. 2003. Additions to the hydroids

(Cnidaria) of the Galápagos, with a list of

species reported from the islands. J Nat Hist.

37: 1173-1218.

CAMPOS CJA, PINHEIRO US, MIGOTTO AE, MAR-

QUES AC. 2012. Selection of sponges as sub-

strata and early life history of the tubulariid

Zyzzyzus warreni (Cnidaria: Hydrozoa) in the

São Sebastião Channel, Brazil. Mar Biol Res.

8: 573-583.

CORREIA KV. 1983. As medusas da plataforma

dos estados do Paraná e Santa Catarina (Ope-

ração CONVERSUT III) sistemática e distri-

buição [MSc thesis]. Curitiba: Setor de Ciên-

cias Biológicas, Universidade Federal do

Paraná. 221 p.

EDWARDS C. 1972. The hydroids and the medusa

Podocoryne areolata, P. borealis and P.

carnea. J Mar Biol Assoc UK. 52: 97-144

FRASER CM. 1938a. Hydroids of the 1934 Allan

Hancock Pacific expedition. Allan Hancock

Pacific Expeditions. 4: 1-105.

FRASER CM. 1938b. Hydroids of the 1932, 1933,

1935 and 1938 Allan Hancock Pacific expedi-

tions. Allan Hancock Pacific Expeditions. 4:

129-153.

FRASER CM. 1939. Distributions of the hydroids

in the collections of the Allan Hancock expe-

ditions. Allan Hancock Pacific Expeditions. 4:

155-178.

FRASER CM. 1948. Hydroids of the Allan Han-

cock Pacific expeditions since March, 1938.

Allan Hancock Pacific Expeditions. 4: 179-

335.

GALEA H. 2007. Hydroids and hydromedusae

(Cnidaria, Hydrozoa) from the fjords region of

southern Chile. Zootaxa. 1597: 1-116.

GALEA H, HÄUSSERMAN V, FÖRSTERRA G. 2007.

Cnidaria, Hydrozoa: latitudinal distribution of

hydroids along the fjords region of southern

Chile, with notes on the world distribution of

some species. Check List. 3: 308-320.

GALEA H, HÄUSSERMAN V, FÖRSTERRA G. 2009.

New additions to the hydroids (Cnidaria:

Hydrozoa) from the fjords region of southern

Chile. Zootaxa. 2019: 1-28. DOI: https://doi.

org/10.11646/zootaxa.2019.1.1

GALEA H, SCHORIES D. 2012. Some hydrozoans

(Cnidaria) from Central Chile and the Strait of

Magellan. Zootaxa. 3296: 19-67.

GENZANO GN, MIANZAN HW, BOUILLON J. 2008.

Hydromedusae (Cnidaria: Hydrozoa) from the

temperate southwestern Atlantic Ocean: a

review. Zootaxa. 1750: 1-18.

GENZANO GN, ZAMPONI MO. 1997. Frequency of

study and diversity of benthic Hydrozoa of the

Argentine Continental Shelf. Cienc Mar. 23:

285-302.

GUERRERO E, GILI J-M, RODRIGUEZ C, ARAUJO E,

CANEPA A, CALBET A, GENZANO G, MIANZAN H,

GONZÁLEZ RA. 2013. Biodiversity and distribu-

tion patterns of planktonic cnidarians in San

Matías Gulf, Patagonia, Argentina. Mar Ecol.

34 (1): 71-82.

HADDAD MA, BETTIM AL, MIGLIETTA MP. 2014.

Podocoryna loyola, n. sp. (Hydrozoa, Hydrac-

tiniidae): a probably introduced species on arti-

ficial substrate from southern Brazil. Zootaxa.

3796: 494-506.

37

GENZANO ET AL.: PODOCORYNA TENUIS (HYDROZOA) IN TEMPERATE WATERS OF SOUTHWESTERN ATLANTIC

HARTLAUB C. 1905. Die Hydroiden der magal-

haensischen Region und chilenischen Küste.

Zoologische Jahrbücher. 6: 497-714.

JÄDERHOLM E. 1905. Hydroiden aus antarktischen

und subantarktischen Meeren gesammelt von

der schwedischen Südpolarexpedition. Wis-

senschaftliche Ergebnisse der Schwedischen

Südpolar-Expedition 1901-1903. 5: 1-41.

JÄDERHOLM E. 1917. Hydroids from the South

Seas. Redogörelse Norrköpings Högre

Allmänna Läroverk Läsaret, 1916-1917. p. 1-

25.

KRAMP PL. 1952. Reports from the Lund Univer-

sity Chile expedition 1948-49. 2. Medusae col-

lected by the Lund University Chile Expedi-

tion 1948-49. Lunds Universitets Årsskrift N.

F. Aud. 2 (47): 3-19.

KRAMP PL. 1959. The Hydromedusae of the

Atlantic Ocean and adjacent waters. Dana Rep.

46: 1-283.

KRAMP PL. 1961. Synopsis of the medusae of the

world. J Mar Biol Assoc UK. 40: 1-469.

MARISCAL RN. 1974. Nematocysts. In: MUSCA-

TINE L, LENHOFF HM, editors. New York: Coe-

lenterate Biology. Academic Press. p. 129-178.

MARQUES AC, COLLINS AG. 2004. Cladistic

analysis of Medusozoa and cnidarian evolu-

tion. Invertebr Biol. 123: 23-42.

MAYER AG. 1910. Medusae of the world. Vol I.

The Hydromedusae. Washington: Carnegie

Institution of Washington. 230 p.

MIGLIETTA MP, CUNNINGHAM CW. 2012. Evolu-

tion of life cycle, colony morphology, and host

specificity in the family Hydractiniidae

(Hydrozoa, Cnidaria). Evolution. 66 (12):

3876-3901.

MIGLIETTA MP, SCHUCHERT P, CUNNINGHAM CW.

2009. Reconciling genealogical and morpho-

logical species in a worldwide study of the

family Hydractiniidae (Cnidaria, Hydrozoa).

Zool Scr. 38: 403-430.

MIGOTTO AE, MARQUES AC, MORANDINI AC, SIL-

VEIRA FL. 2002. Checklist of the Cnidaria

Medusozoa of Brazil. Biota Neotrop. 2: 1-31.

MILLARD NAH. 1975. Monograph on the Hydroi-

da of Southern Africa. Ann S Afr Mus. 68: 1-

513.

MIRANDA TP, GENZANO GN, MARQUES AC. 2015.

Areas of endemism in the Southwestern

Atlantic Ocean based on the distribution of

benthic hydroids (Cnidaria: Hydrozoa). Zoo-

taxa. 4033: 484-506.

NOGUEIRA JRM, PUKANSKI LEM, SOUZA-CONCEI-

ÇÃO JM. 2015. Mesh size effects on assess-

ments of planktonic hydrozoan abundance and

assemblage structure. J Mar Sys. 144: 117-126.

OLIVEIRA OMP, MIRANDA TP, ARAUJO EM, AYÓN

P, CEDEÑO-POSSO CM, CEPEDA-MERCADO AA,

CÓRDOBA CUNHA AFP, GENZANO GN, HADDAD

MA, et al. 2016. Census of the Cnidaria (Medu-

sozoa) and Ctenophora from South American

marine waters. Zootaxa. 4194: 1-256.

PAGÈS F, OREJAS C. 1999. Medusae, siphonophores

and ctenophores of the Magellan region. Sci

Mar. 63: 51-57.

PALMA S, ABAPLAZA P, SILVA N. 2007a. Hydrom-

edusae (Cnidaria) of the Chilean southern

channels (from the Corcovado Gulf to the Pul-

luche-Chacabuco Channels). Sci Mar. 71: 65-

74.

PALMA S, ABAPLAZA P, SOTO D. 2007b. Diversity

and aggregation areas of planktonic cnidarians

of the southern channels of Chile (Boca del

Guafo to Pulluche Channel). Invest Mar. 35:

71-82.

PALMA S, NELSON SILVA A, RETAMAL MC, CASTRO

L. 2011. Seasonal and vertical distributional

patterns of siphonophores and medusae in the

Chiloé Interior Sea, Chile. Cont Shelf Res. 31:

260-271.

SCHUCHERT P. 2001. Hydroids of Greenland and

Iceland (Cnidaria, Hydrozoa). Medd Groenl

Geosc. 53: 1-184.

SCHUCHERT P. 2008. The European athecate

hydroids and their medusae (Hydrozoa,

Cnidaria): Filifera part 3. Rev Suisse Zool.

115: 221-302.

SEGURA-PUERTAS L. 1984. Morfología, sistemáti-

38 MARINE AND FISHERY SCIENCES 37 (1): 27-39 (2024)

ca y zoogeografía de las medusas (Cnidaria:

Hydrozoa y Scyphozoa) del Pacífico Tropical

Oriental. Instituto de Ciencias del Mar y Lim-

nología, Universidad Nacional Autónoma de

México. Publicación Especial. 8: 1-320.

SILVEIRA FL, MORANDINI AC. 2011. Checklist dos

Cnidaria do Estado de São Paulo, Brasil. Biota

Neotrop. 11: 1-10.

STAMPAR SN, TRONOLONE VB, MORANDINI AC.

2006. Description and life cycle of the hydro-

zoan Hydractinia uniformis, sp. nov. (Cnidaria:

Hydrozoa: Hydractiniidae), from the Ocean of

southeastern Brazil. Zootaxa. 1200: 43-59.

TRONOLONE VB. 2001. Hidromedusas (Cnidaria,

Hydrozoa) do canal de São Sebastião, SP

[MSc thesis]. São Paulo: Instituto de Biociên-

cias, Universidade de São Paulo. 179 p.

VILLENAS F, SOTO D, PALMA S. 2009. Cambios

interanuales en la biomasa y biodiversidad de

zooplancton gelatinoso en el sur de Chile (pri-

maveras 2004 y 2005). Rev Biol Mar Ocea-

nogr. 44: 309-324.

WEDLER E. 1975. Ökologische Untersuchungen an

Hydroiden des Felslitorals von Santa Marta

(Kolumbien). Helgol Wissenschaftliche Meere-

sunters. 27: 324-363.

39

GENZANO ET AL.: PODOCORYNA TENUIS (HYDROZOA) IN TEMPERATE WATERS OF SOUTHWESTERN ATLANTIC