POPULATION STRUCTURE AND BREEDING SEASON OF THE SOUTH ATLANTIC HERMIT CRAB, LOXOPAGURUS LOXOCHELIS (ANOMURA, DIOGENIDAE) FROM THE UBATUBA REGION, BRAZIL

• Published in: Crustaceana 2002-06, Vol.75 (6), p.791-802
• Main Authors: Martinelli, Jussara, Mantelatto, Fernando, Fransozo, Adilson
• Format: Article
• Language: English
• Subjects: Loxopagurus loxochelis; Marine
• ISSN: 0011-216X; 1568-5403; 0011-216X
• DOI: 10.1163/156854002760289764

A population of Loxopagurus loxochelis was studied in terms of seasonal abundance, size frequency distribution, sex ratio, and reproductive period (percentage of ovigerous females). Specimens were collected monthly over a period of two years (from September 1995 to August 1997) in the non-consolidated areas of the Ubatuba, Mar Virado, and Ubatumirim bays (northern coast of Sao Paulo State, Brazil) with a double-rig trawl net. A total of 1,084 individuals were analysed. Animal size (minimum, maximum, and mean plus or minus SD shield length) was 2.8, 9.1, and 6.88 plus or minus 1.13 mm for 625 males; 2.8, 8.2, and 5.78 plus or minus 0.98 mm for 236 non-ovigerous females; and 4.6, 8.0, and 6.24 plus or minus 0.68 mm for 223 ovigerous females, respectively. Sexual dimorphism was recorded by the presence of males in the largest size classes. The sex ratio was 1.4:1 in favour of males. The highest incidence of ovigerous females occurred during winter and spring (June to October), with a low percentage in summer and fall (November to May), indicating continuity in the reproductive cycle. This strategy of reproduction is related to temperature. The occurrence of L. loxochelis in the Ubatuba region represents the final point of northern distribution of this species as a function of water mass influence, and could be its real limit on the Atlantic coast of South America.Original Abstract: Uma populacao do ermitao Loxopagurus loxochelis foi estudada com relacao a sua abundancia sazonal, distribuicao de frequencia de tamanho, razao sexual e periodo reprodutivo (porcentagem de femeas ovigeras). Os especimens foram coletados mensalmente, por um periodo de 2 anos (Setembro 1995 a Agosto 1997) em areas de substrato nao-consolidado das Enseadas de Ubatuba, Mar Virado e Ubatumirim (costa norte do Estado de Sao Paulo, Brasil) com uma rede do tipo "double-rig". Um total de 1.084 individuos foram analisados. Os tamanhos dos exemplares (minimo, maximo e media plus or minus SD do comprimento do escudo cefalotoracico) foram 2,8, 9,1 e 6,88 plus or minus 1,13 mm para 625 machos; 2,8, 8,2 e 5,78 plus or minus 0,98 mm para 236 femeas nao ovigeras; e 4,6, 8,0 e 6,24 plus or minus 0,68 mm para 223 femeas ovigeras, respectivamente. O dimorfismo sexual foi registrado pela presenca de machos nas maiores classes de tamanho. A razao sexual foi de 1,4 : 1 em favor dos machos. A maior incidencia de femeas ovigeras ocorreu no inverno e na primavera (Junho a Outubro), com uma baixa porcentagem