Dimorphism in males of Zaops ostreum (Say) (Crustacea, Decapoda, Pinnotheridae)

Abstract

ABSTRACT. A case of dimorphism among the males of the pinnotherid crab, Zaops ostreum (Say, 1817), is reported. The morpho1ogical features ofthe two types ofmales are also given. KEY WORDS. Zaops ostreulIl, dimorphism, males A study being carried out to determine the diversity of carcinofauna of the estuaries ofthe State ofRio Grande do Norte has recorded Zaops ostreum (Say, 1817) associated with the oyster Crassostrea rhizophorae in the estuary near Macau , Rio Grande do Norte, Brazil. Though C. rhizophora is not uncommon in the other estuaries under investigation, the presence of Z. ostreum has not been recorded so faro Though sexual dimorphism is a common phenomenon among the pinnotherid crabs necessitating separate keys for males and females for the identification of the species (RATHBuN 1918; WILLlAMS 1984; MANNING 1993), the existence of two types of males within the same population is not common.Of the fo ur estuaries under investigation (Macau, Galinhos, Potengi and Guaraira), the oysters attached to the mangrove vegetation are common in the first three of them. However, the material for this report was obtai ned only from the estuary of Macau -a total of 39 females and 26 males. The table I shows how they were distributed within the oysters. A detailed examination of the males revealed the existence of two distinct types of males (Fig. 1) within the same population . The principal differences are in the shape of the carapace, the shape of lhe frontallobe and the shape and size of the

Pea crab-oyster interspecific interaction on tropical coast: Brachyuran pinnotherid Zaops ostreum (Say, 1817) living in the host bivalve ostreid Crassostrea brasiliana (Lamarck, 1819)

“…During the dry season occurred a high decrease of non-ovigerous females (no non-ovigerous females found from September to December), indicating a reproductive peak during this season. Contrasting with the results obtained by Sankarankutty and Ferreira (2001) in C. rhizophorae at Macau Estuary (State of Rio Grande do Norte, Northeast Brazil), most of our occurrences were female-male couples (mean 79.29%) without isolated males and triple occupancy, while the previous authors reported lower female-male couples' rate (28,83%), as well as isolated males and triple occupancy (Sankarankutty and Ferreira, 2001). Nonetheless, no female-male couples were recorded on September at Barra de Catuama (this study) and Macau Estuary (Sankarankutty and Ferreira, 2001).…”

“…Contrasting with the results obtained by Sankarankutty and Ferreira (2001) in C. rhizophorae at Macau Estuary (State of Rio Grande do Norte, Northeast Brazil), most of our occurrences were female-male couples (mean 79.29%) without isolated males and triple occupancy, while the previous authors reported lower female-male couples' rate (28,83%), as well as isolated males and triple occupancy (Sankarankutty and Ferreira, 2001). Nonetheless, no female-male couples were recorded on September at Barra de Catuama (this study) and Macau Estuary (Sankarankutty and Ferreira, 2001). These results obtained in tropical environments highly contrast with results obtained by Christensen and McDermott (1958) at the Bay Shore Channel (USA), were reproductive seasons seem be rather accentuated, with distinct periods for double occupancy and prolonged declines on male abundances after copulation.…”

“…Ecological interactions involving the pea crab Z. ostreum and other species of the family Ostreidae have been previously discussed, mainly in association with C. rhizophorae and C. virginica (Stauber, 1945;O'Beirn and Walker, 1999;Sankarankutty and Ferreira, 2001;Bezerra et al, 2006;Sabry et al, 2011;Hanke et al, 2015;De Gier and Becker, 2020). Studies detected that Z. ostreum may provoke harms/injuries in soft-parts-oyster of C. rhizophorae and C. virginica during the feeding behaviour (Hanke et al, 2015), particularly in gills/branchial chambers, including demibranchs, and on the adductor muscle (Stauber, 1945;Christensen and McDermott, 1958), recognizing a disharmonious relationship with Z. ostreum acting as parasite in the oysters (Nascimento and Pereira, 1980).…”

“…Sustent., 2023, vol. 10, n. 24, p. 183-195. The genus Zaops Rathbun, 1900 comprises three valid species of the Family Pinnotheridae found in West Atlantic waters, among which only Zaops ostreum (Say, 1817) is reported on Brazilian coastal environments from Northeast to Southern Brazil (Nascimento and Pereira, 1980;Martins and D'Incao, 1996;Sankarankutty and Ferreira, 2001;Bezerra et al, 2006;Felder et al, 2009;Almeida et al, 2010;Boehs et al, 2012). Z. ostreum is characterized by arched-shape orbits, cephalothorax curved on both sides of the carapace, clypeus emarginate at anterior end, and chelipeds covered with white hairs (Say, 1817;Melo, 1996).…”

“…Z. ostreum is characterized by arched-shape orbits, cephalothorax curved on both sides of the carapace, clypeus emarginate at anterior end, and chelipeds covered with white hairs (Say, 1817;Melo, 1996). It is known to be parasitic on bivalve oysters of the genus Crassostrea Sacco, 1897, including Crassostrea rhizophorae (Guilding, 1828) and Crassostrea virginica (Gmelin, 1791) (Stauber, 1945;Christensen and McDermott, 1958;Beach, 1969;Nascimento and Pereira, 1980;Martins and D'Incao, 1996;Melo, 1996;O'Beirn and Walker, 1999;Sankarankutty and Ferreira, 2001;McDermott, 2009;Almeida et al, 2010;Hanke et al, 2015), which can cause economic losses in aquaculture. Z. ostreum has an interspecific relationship with the oysters' species, feeding on the phytoplankton and zooplankton that these oysters filter (McDermott, 1997;Almeida et al, 2010;Hanke et al, 2015).…”