New records of intersexuality in porcelain crabs ( Crustacea : Decapoda : Anomura : Porcellanidae )

Th e occurrence of intersex specimens of Lissoporcellana quadrilobata (Miers, 1884), Pisidia bluteli (Risso, 1816) and Pisidia longimana (Risso, 1816) is recorded for the fi rst time and their secondary sexual characters analyzed. Intersex specimens were collected in regions regularly aff ected by pollution. Th ere is a high possibility that intersexuality in porcelain crabs is caused by environmental contamination. keY woRds Intersex, Malacostraca, pollution, anomuran crabs, sexual characters. Decapod crustaceans are typically gonochoric, with a more or less pronounced sexual dimorphism. In porcelain crabs, the most obvious external characters of females are three pairs of uniramous pleopods located on the third, fourth and fi ft h abdominal somites, although the pleopod on the third somite is sometimes absent (e.g., Polyonyx Stimpson, 1858). Males occasionally have highly modifi ed pleopods (= gonopods) located on the second abdominal somite (gonopods are absent in some species of Pachycheles Stimpson, 1858 and Polyonyx). Male gonopods are biramous, with a long protopod, a well-developed endopod and usually a quite reduced exopod. In all decapods, gonopores are situated on the coxae of the third pereopods (P3) in females, and on the coxae of the fi ft h pereopods (P5) in males. Th e specimens that have gonopore openings on both P3 and P5 are called intersex individuals (Turra, 2004). In porcelain crabs, intersexuality has been only reported in two species: Porcellana platycheles (Pennant, 1777) and Pisidia longicornis (Linnaeus, 1767) by Ferreira and Guzmán (2013) and Ferreira (2015), respectively. Ferreira (2015) identifi ed an ovigerous intersex specimen in P. longicornis, representing the fi rst record of this condition in porcelain crabs. Th e present paper aims to report new records of intersexuality in three additional porcellanid crabs: Lissoporcellana quadrilobata (Miers, 1884), Pisidia bluteli (Risso, 1816) and Pisidia longimana (Risso, 1816).


keY woRds
Intersex, Malacostraca, pollution, anomuran crabs, sexual characters.Decapod crustaceans are typically gonochoric, with a more or less pronounced sexual dimorphism.In porcelain crabs, the most obvious external characters of females are three pairs of uniramous pleopods located on the third, fourth and fi ft h abdominal somites, although the pleopod on the third somite is sometimes absent (e.g., Polyonyx Stimpson, 1858).Males occasionally have highly modifi ed pleopods (= gonopods) located on the second abdominal somite (gonopods are absent in some species of Pachycheles Stimpson, 1858 and Polyonyx).Male gonopods are biramous, with a long protopod, a well-developed endopod and usually a quite reduced exopod.In all decapods, gonopores are situated on the coxae of the third pereopods (P3) in females, and on the coxae of the fi ft h pereopods (P5) in males.Th e specimens that have gonopore openings on both P3 and P5 are called intersex individuals (Turra, 2004).

Records of intersexuality in porcelain crabs
Nauplius, 26: e2018009 The porcellanid material examined (Appendix 1) is deposited in the National Museum of Natural History, Smithsonian Institution, Washington DC, USA (USNM), and was thoroughly examined under a stereomicroscope.The sex of individuals was determined based on the position of the gonopores on either P3 (males) or P5 (females), whereas secondary sexual characters were scored based mainly on the morphology of the sternum, abdomen and pleopods.In addition, gill and abdominal chambers of the porcellanid specimens were examined for presence of macro-parasites (bopyrid isopods and rhizocephalan barnacles).
Of 23 specimens of L. quadrilobata examined, two individuals were determined as intersex (Fig. 1A).Both intersex specimens have male dominant characters such as male gonopores on the P5 and well-developed gonopods on the second abdominal somites, in addition to well-developed female gonopores on the P3.
Sixteen specimens of P. bluteli were examined and five individuals among them were determined as intersex (Fig. 1B, C).Three of the intersex specimens possess male dominant characters (a pair of male gonopores and well-developed gonopods) and a pair of rudimentary female gonopores.The other two intersex specimens have female dominant characters such as broad thoracic sternum, female pleopods and well-developed female gonopores, in addition to male gonopores.
Of approximately 300 specimens of P. longimana examined, four intersex were identified (Fig. 1D).All the individuals have dominant male characters (a pair of male gonopores and well-developed gonopods) in addition to a pair of well-developed female gonopores.
No parasitic bopyrid isopods or rhizocephalan barnacles were found in intersex specimens examined, and no abnormalities were found on the carapace, pereopods, abdomen or pleopods.
The occurrence of intersex specimens is frequently attributed to localities suffering from pollution (Gusev and Zabotin, 2007;Yang et al., 2008;Fantucci et al., 2009;Sant' Anna et al., 2010;Ferreira and Guzmán, 2013;Ferreira, 2015).In the present study, intersex individuals of L. quadrilobata, P. bluteli and P. longimana were indeed collected from regions regularly affected by pollution resulting from activities of coastal industries, harbors, ligthhouses and boating.Localities within the sampling region often experience impacts from discharge of commercial vessels, fuel and other discharge of pollutants (Aissaoui and Hassine, 2012;Perkovic et al., 2016;Randone, 2016).Ferreira (2015) have already observed intersex individuals of Pisidia longicornis collected from a polluted region caused by sunken oil tankers or by illegal fuel discharges.Therefore, it is possible that intersexuality observed in porcelain crabs in the studied area is caused by environmental contamination.
Since no bopyrid or rhizocephalan parasites were found associated with intersex specimens, and no abnormalities were found on their carapace, abdomen or pleopods, it is unlikely that parasitism is the cause of intersexuality in these crabs.Due to the fact that the incidence of porcellanid intersex specimens is low, another reasonable hypothesis is that intersexuality can be attributed to a genetic abnormality.

Records of intersexuality in porcelain crabs
Nauplius, 26: e2018009 Appendix 1. Porcellanid intersex examined in the present study.Collection numbers are indicated in brackets.