Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73 (S2): e64534, mayo 2025 (Publicado May. 15, 2025)

Revalidation of Ptychophallus campylus Pretzmann, 1968, a freshwater crab

species from Costa Rica (Decapoda: Brachyura: Pseudothelphusidae)

Célio Magalhães1, 2*; http://orcid.org/0000-0003-4858-2575

Ingo S. Wehrtmann3, 4, 5, 6; https://orcid.org/0000-0002-6826-7938

Fernando L. Mantelatto1; http://orcid.org/0000-0002-8497-187X

1. Laboratório de Bioecologia e Sistemática de Crustáceos (LBSC), Departamento de Biologia, Faculdade de Filosofia,

Ciências e Letras de Ribeirão Preto (FFCLRP), Universidade de São Paulo (USP). Av. Bandeirantes, 3900; 14040-901,

Ribeirão Preto, SP, Brazil; celiomag@usp.br (*Correspondence); flmantel@usp.br

2. Instituto Nacional de Pesquisas da Amazônia, 69080-971 Manaus, AM, Brazil.

3. Museo de Zoología of the Centro de Investigación en Biodiversidad y Ecología Tropical (CIBET), Universidad de Costa

Rica, 11501-2060 San José, Costa Rica; ingo.wehrtmann@ucr.ac.cr

4. Unidad de Investigación Pesquera y Acuicultura (UNIP) of the Centro de Investigación en Ciencias del Mar y

Limnología (CIMAR), Universidad de Costa Rica, 11501-2060 San José, Costa Rica.

5. Escuela de Biología, Universidad de Costa Rica, San José, Costa Rica.

6. Editorial Universitaria, Universidad del Valle de Guatemala, 18 Avenida 11-95, Zona 15, Vista Hermosa III, Ciudad de

Guatemala, Guatemala; iswehrtmann@uvg.edu.gt

Received 31-VIII-2024. Corrected 22-I-2025. Accepted 14-III-2025.

ABSTRACT

Introduction: Freshwater crab diversity in the Neotropics is high, comprising three families: Epiloboceridae,

Pseudothelphusidae and Trichodactylidae. The genus Ptychophallus consists of 13 species, all from Panama and

Costa Rica. Ptychophallus campylus has not been recognized as a valid species and has been treated as a presump-

tive junior synomym of Ptychophallus tristani.

Objective: The present study aims to formalize the resurrection of P. campylus as a valid species.

Methods: An additional specimen of P. campylus collected in the province of Limón, Costa Rica, was analyzed

and compared to both the holotype of P. campylus and the description of P. tristani.

Results: The gonopod 1 of P. campylus is morphologically similar to that of P. tr i s t a ni but can be differentiated

by the shape of the lateral process of the male first gonopod. Moreover, both species show different geographic

distributions: whereas P. t r i stani occurs in hydrographic basins of the Pacific versant of Costa Rica, P. campylus

seems to be restricted to the Caribbean slope in eastern Costa Rica.

Conclusions: Ptychophallus campylus is formally revalidated from the synonymy of P. t r i s t ani, confirming

recently published results of multigene analysis that recovered both species in different lineages. This revalidation

of P. campylus increases the number of valid species of the genus Ptychophallus to a total of 14, with nine species

or 64.2% of all Ptychophallus species occurring in Costa Rica.

Keywords: Central America, Neotropical region, Ptychophallinae, synonymy, taxonomy.

RESUMEN

Revalidación de Ptychophallus campylus Pretzmann, 1968, una especie de cangrejo

de agua dulce de Costa Rica (Brachyura: Decapoda: Pseudothelphusidae)

Introducción: La diversidad de cangrejos de agua dulce en el Neotrópico es alta y comprende tres familias:

Epiloboceridae, Pseudothelphusidae y Trichodactylidae. El género Ptychophallus consta de 13 especies, todas

https://doi.org/10.15517/rev.biol.trop..v73iS2.64534

SUPPLEMENT

SECTION: MUSEUM

2Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73 (S1): e64534, mayo 2025 (Publicado May. 15, 2025)

INTRODUCTION

Primary or true freshwater crabs inhabit

tropical and subtropical regions around the

world and are characterized by having adopted

freshwater, semi-terrestrial or terrestrial modes

of life, being completely independent of marine

environments, and showing direct develop-

ment, hatching as fully developed juveniles

(Cumberlidge & Ng, 2009; Magalhães et al.,

2016; Vogt, 2016; Yeo et al., 2008).

Freshwater crabs are highly diverse in the

Neotropics, comprising 311 species within

three families: Epiloboceridae, Pseudothelphu-

sidae and Trichodactylidae (Álvarez et al., 2020;

Cumberlidge et al., 2014; Magalhães et al.,

2016). Colombia and Mexico are considered as

hotspots of freshwater crab diversity (Cumber-

lidge et al., 2014), and in Central America Pan-

ama and Costa Rica have the highest diversity

with 17 and 15 species, respectively (Magalhães

et al., 2015).

A total of eight subfamilies have been rec-

ognized within the family Pseudothelphusidae,

and the genus Ptychophallus forms part of the

subfamily Ptychophallinae (see Álvarez et al.,

2020). According to Magalhães et al. (2015),

the genus Ptychophallus consists of 13 spe-

cies, exclusively reported from Costa Rica and

Panama. One of these species is Ptychophallus

campylus Pretzmann, 1968, only known from

Costa Rica, presenting a somewhat enigmatic

case since Pretzmann (1968) provided only a

brief description from a single male collected in

an unknown location in Costa Rica. Moreover,

this description lacks illustrations of both the

specimen and of its male first gonopod (G1),

which is typically used for the species identi-

fication of freshwater crabs (Smalley, 1964a;

Rodriguez, 1982). He later provided some low-

resolution photographs of the carapace and

G1 of P. campylus in his taxonomic revision

of the pseudothelphusid crabs (Pretzmann,

1972). Judging solely from Pretzmann’s (1972)

description, Rodriguez (1982) considered P.

campylus indistinguishable from Ptychophallus

tristani (Rathbun, 1896) regarding morpho-

logical characters of their G1s. Even though

Magalhães et al. (2015) examined the holotype

of P. campylus, they also preferred to keep it

provisionally as a junior subjective synonym

of P. tr i s ta ni . Although these authors verified

some morphological differences between the

G1s of both species, they cautiously preferred

to wait until additional collections could clearly

show the differentiation between these taxa.

Following the identification of a specimen as

Ptychophallus campylus and its inclusion in a

recent multigene study of several species within

the genus Ptychophallus Smalley, 1964b, (Man-

telatto et al., 2024), the phylogenetic distinction

between the two species was confirmed. There-

fore, the present study aims to formalize the

resurrection of P. campylus as a valid species.

de Panamá y Costa Rica. Ptychophallus campylus no se ha reconocido como especie válida y se ha tratado como

presunto sinónimo junior de Ptychophallus tristani.

Objetivo: El presente estudio pretende formalizar la resurrección de P. campylus como especie válida.

Métodos: Se analizó un espécimen adicional de P. campylus recolectado en la provincia de Limón, Costa Rica, y

se comparó tanto con el holotipo de P. campylus como con la descripción de P. tr i s t a ni .

Resultados: El gonópodo 1 de P. campylus es morfológicamente similar al de P. t r i s t ani, pero puede diferenciarse

por la forma del proceso lateral del primer gonópodo del macho. Además, ambas especies muestran distribucio-

nes geográficas diferentes: mientras que P. tr i s t a n i habita en cuencas hidrográficas de la vertiente Pacífico de Costa

Rica, P. campylus parece estar restringida a la vertiente del Caribe en el este de Costa Rica.

Conclusión: Ptychophallus campylus se revalida formalmente de la sinonimia de P. t r i stani, confirmando los

resultados recientemente publicados del análisis multigénico que recuperó ambas especies en linajes diferentes.

Esta revalidación de P. campylus aumenta el número de especies válidas del género Ptychophallus a un total de 14,

con nueve especies o el 64,2% de todas las especies de Ptychophallus presentes en Costa Rica.

Palabras clave: América Central, región neotropical, Ptychophallinae, sinonimia, taxonomía.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73 (S2): e64534, mayo 2025 (Publicado May. 15, 2025)

MATERIALS AND METHODS

The specimens examined are deposited

in the crustacean collection of the Museo de

Zoología, Centro de Investigación en Biodiver-

sidad y Ecología Tropical (CIBET), Universidad

de Costa Rica, San José (UCR-MZ), Naturhisto-

risches Museum Wien, Vienna (NHMW), and

National Museum of Natural History, Smith-

sonian Institution, Washington, DC (USNM).

The following abbreviations were used: cara-

pace width (cw), measured across the cara-

pace at its widest point; carapace length (cl),

measured along the midline, from the frontal

to the posterior margin; male first gonopod

(G1). Measurements are in millimeters. The

terminology for the description of the gonopod

morphology follows Magalhães et al. (2015).

RESULTS

Family Pseudothelphusidae

Ortmann, 1893

Subfamily Ptychophallinae Álvarez, Ojeda,

Souza-Carvalho, Villalobos, Magalhães,

Wehrtmann & Mantelatto, 2020

Genus Ptychophallus Smalley, 1964b

Ptychophallus campylus Pretzmann, 1968 stat.

restit. (Fig. 1)

Ptychophallus (Ptychophallus) campylus

Pretzmann, 1968: 13. — Pretzmann, 1971: 21.

— Pretzmann, 1972: 87, figs. 537–539, 559–561.

Ptychophallus campylus — Rodriguez,

1982: 80. — Mantelatto et al., 2024: 3 (table 1),

4 (fig. 1), 5.

Ptychophallus tristani — Magalhães et al.,

2015: 320, fig. 41 [part; only holotype of P. (P.)

campylus, NHMW 21849]

Description of G1 (Fig. 1A, B). Robust and

straight in mesiocaudal view. Marginal suture

on mesial side, nearly straight; marginal process

rounded, not produced beyond distal border of

apex, strongly bent to cephalic side. Mesial pro-

cess large, subrectangular, axe-shaped. Lateral

process long, approximately 60% of stem length

(measured from proximal opening to caudal

border of apex), clearly bilobed; lobes strongly

asymmetric, with wide median concavity on

caudal surface between lobes; proximal lobe

rounded, slightly broader than distal lobe, with

Fig. 1. Male left first gonopod, caudomesial view. A. Ptychophallus campylus Pretzmann, 1968: UCR-MZ 3226-02; B.

Ptychophallus campylus: holotype, NHMW 21849. C. Ptychophallus tristani (Rathbun, 1896): holotype, USNM 19047.

Abbreviations: a, lateral end of the apex; me, mesial process; dl, distal lobe of the lateral process. Scale bar: A = 2 mm; B,

C = 1 mm. B and C from Magalhães et al. (2015: 316, figs. 41 and 39, respectively), reproduced with permission from the

4Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73 (S1): e64534, mayo 2025 (Publicado May. 15, 2025)

some scattered minute setae on caudal, lateral

surfaces; distal lobe narrower, slightly trans-

versal and thicker distally on cephalic surface,

distinctly shorter than lateral end of apex. Dis-

tocaudal ridge narrow, somewhat sinuous, not

reaching level of median depression of lateral

process, well separated from distal border of

lateral process by distinct depression. Apex

bent approximately 90° towards lateral side;

oblong, narrow in distal view; caudal border

with narrow notch near lateral end. Field of

apical spines well developed, facing towards

cephalolateral side.

Material examined. Costa Rica: male (cw

29.4, cl 19.4), holotype, NHMW 21849, collec-

tion location unknown, 1913, Fassl leg.; 1 male

(cw 35.2 mm, cl 22.4 mm), UCR-MZ 3226-02,

province Limón, Veraguas Rainforest Adven-

ture Park [09°55’34.75”N 83°11’26.75”W], que-

brada Campamento, 26.vii.2013, D. Hernández

and L. Vargas leg.

Distribution. The species is currently only

known from eastern Costa Rica, in the Carib-

bean versant.

Genetic sequences accession number

(GenBank): 16S ribosomal RNA - OR116815;

Cytochrome Oxidase Subunit I - OR122823;

Histone 3 (H3) OR141946.

DISCUSSION

Despite some differences in the G1 mor-

phology, Magalhães et al. (2015) did not recog-

nize P. campylus as a valid species and preferred

to treat it as a presumptive junior synomym of

P. tr i s ta ni until additional material was avail-

able. The G1 morphology of an adult male

specimen from eastern Costa Rica (Fig. 2A)

proved to be nearly identical to that of the holo-

type of P. campylus (Fig. 2B). In the molecular

phylogenetic analysis carried out by Mantelatto

et al. (2024) using two mitochondrial (16 S

rRNA and COI) and one nuclear (H3) genes,

these two species were clearly recovered as

separate lineages either in the concatenated

phylogram: P. campylus in the Lineage A and

P. tr i s ta ni in Lineage C (Mantelatto et al., 2024:

fig. 1) or in the individual phylograms for each

gene (Supplementary material, figs. S2–S4 in

Mantelatto et al., 2024). Considering these

results, the authors recommended a reassess-

ment of the taxonomic status of both species.

Although positioned in separate lineages

in the Mantelatto’s et al. (2024) study, the G1 of

P. campylus is morphologically similar to that of

P. tr i s ta ni in terms of the large, subrectangular,

axe-shaped mesial process, a character only

shared by these two among all the species of

the genus. The G1 of both species can be dif-

ferentiated by the shape of the lateral process:

in the adult specimen of P. campylus examined

herein, the distal lobe of the lateral process is

less developed than in P. t r i sta ni (it is distinctly

shorter than the lateral end of apex and nar-

rower in the former species versus longer and

broader in the latter one — see Fig. 1). The

shape of the lateral process in P. tr i s t an i can be

somewhat variable and, in a few cases, appears

to be similar to that of P. campylus (see Magal-

hães et al., 2015). Their geographic distribution

areas, however, are different: whereas P. t r i sta ni

occurs in hydrographic basins of the Pacific

versant of Costa Rica (Magalhães et al., 2015:

339, fig. 83), P. campylus seems to be restricted

to the Caribbean slope in eastern Costa Rica

(present paper).

After more than five decades since the

original description and after serious doubts

about the systematic position of the species, the

revalidation of P. campylus is herein presented

and increases the number of valid species of the

genus Ptychophallus to a total of 14. Of these,

nine species or 64.2% of all Ptychophallus spe-

cies have been reported from Costa Rica.

Ethical statement: The authors declare

that they all agree with this publication and

made significant contributions; that there is no

conflict of interest of any kind; and that we fol-

lowed all pertinent ethical and legal procedures

and requirements. All financial sources are

fully and clearly stated in the acknowledgments

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73 (S2): e64534, mayo 2025 (Publicado May. 15, 2025)

section. A signed document has been filed in

the journal archives.

ACKNOWLEDGMENTS

We are grateful to Dayan Hernández for

making the specimen available for our study.

We would like to thank the Conselho Nacio-

nal de Desenvolvimento Científico e Tecno-

logico (CNPq - Brazil, Procs. 491490/2004-6,

490353/2007-0, 490314/2011-2; 471011/2011-

8; PQ 302253/2019–0), Fundação de Amparo

à Pesquisa do Estado de São Paulo (FAPESP

Programa Biota Temáticos 2010/50188–8 and

INTERCRUSTA 2018/13685–5), and CONIC-

IT - Costa Rica (CII-001-08, IQ-0001-11),

which provided financial support to FLM, CM,

and ISW during the Brazil-Costa Rica scientific

cooperation program, making possible analysis

of material and discussions. ISW is greatful

for the support provided by the Universidad

de Costa Rica for his projects related to the

results presented in this contribution: Vicerrec-

toría de Investigación, # 808-B3-504, 808-B6-

773 and 808-C2-721. Specimens collected were

obtained and analyzed under the collection

and genetic access permit Resolución No. 377

- Comisión Institucional de Biodiversidad de la

Universidad de Costa Rica to ISW as part of the

project No B6-733 of the Universidad de Costa

Rica. We would like to thank two anonymous

reviewers for their useful comments and sug-

gestions, which further improved the quality of

this contribution.

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