Gonadal development and sexuality of Larkinia grandis (Arcida: Arcidae) inhabiting southeastern Gulf of California

ABSTRACT Larkinia grandis (Broderip & G.B. Sowerby I, 1829), an important fishing resource for Mexican communities, is an Arcidae clam. It is also considered a species with aquaculture potential. In this work we investigated the gonadal phases and sexuality in a population of L. grandis in the Gulf of California. Our findings support the hypothesis that there is one male per female in the population studied. It also documents that the shape, position and color of the gonads of L. grandis are consistent with observations in other Arcidae species. Additionally, five gonadal phases are differentiated and described in males and females (development, mature, spawning, post-spawning and resting), with a noticeable presence of brown cells during post-spawning and the onset of the resting phase, suggesting that those cells are involved in the reabsorption of remnants. Additionally, asynchronous gametogenesis in males, synchronic gametogenesis in females and batch spawning are defined. The results of this contribution can be used in the efforts to protect this bivalve.

摘要 大蚶（Larkinia grandis, Broderip & G.B. Sowerby I, 1829）是墨西哥社区重要的渔业资源物种，隶属于蚶科（Arcidae）蛤蜊类，同时也被认为具备水产养殖潜力。本研究针对加利福尼亚湾海域的大蚶种群展开调查，探究其性腺发育阶段（gonadal phases）与性别特征。研究结果验证了所研究种群雌雄个体数量比例为1:1的假说；同时证实，大蚶的性腺形状、位置及颜色特征，与其他蚶科物种的观测结果一致。本研究还区分并描述了雌雄个体共5个性腺发育阶段：发育期、成熟期、产卵期、产卵后期与休止期；在产卵后期及休止期起始阶段，可观察到显著的褐色细胞富集现象，提示这类细胞参与了生殖残余物的重吸收过程。此外，本研究明确了雄性配子发生（gametogenesis）具有异步性、雌性配子发生具有同步性，且种群存在分批产卵（batch spawning）的繁殖策略。本研究成果可为该双壳类（bivalve）物种的保护工作提供理论支撑。