Ontogenetic development of gonads and external sexual characters of the protandric simultaneous hermaphrodite peppermint shrimp, Lysmata vittata (Caridea: Hippolytidae).

Daming Chen,Haihui Ye,Chaoshu Zeng,Zhihuang Zhu,Fang Liu,Qi Lin

doi:10.1371/journal.pone.0215406

Daming Chen, Haihui Ye + Show 4 more

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https://doi.org/10.1371/journal.pone.0215406

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Abstract

The peppermint shrimp Lysmata vittata (Caridea: Hippolytidae) is a marine caridean shrimp popular in marine aquarium trade. The species is known to display the sexual system of protandric simultaneous hermaphrodite. In this study, based on captive bred specimens, the complete ontogenetic gonad development of L. vittata was studied both morphologically and histologically, from newly settled juveniles until they reached euhermaphrodite phase. It was found that in all specimens examined (carapace length: 1.8–8.5 mm), including the newly settled juveniles, possessed ovotestes, which comprised of an anterior ovarian and a posterior testicular part. Based on both morphological (e.g., size, color and shape) and histological features (e.g., oogenesis and spermatogenesis), four gonadal development stages were defined and described for L. vittata. From Stage I to III, the testicular part of the gonad became gradually mature but the ovarian part was still immature, which is defined as the male phase. At the male phase, cincinulli (5–8 hooks) presented at the tips of the appendix interna on the first pair of pleopods while appendices masculinae (AM), in a form of a stick structure with spines, presented at the inner edge of the appendix interna (AI) on the second pair of pleopods. At Stage IV, both the testicular part and the ovarian part were mature and hence is defined as euhermaphrodite phase. At the euhermaphrodite phase, most individuals lacked cincinulli and appendices masculinae on the first and second pair of pleopods respectively. This is the first time that complete ontogenetic gonadal and external sexual character development have been described and staged for a species from the genus Lysmata from newly settled juveniles to euhermaphrodite phase.

Highlights

The vast majority of crustacean species are gonochoristic, the caridean shrimp species belonging to the family Hippolytide display more diverse sexual systems of both gonochorism and hermaphroditism
All known species from the genus Lysmata have so far been confirmed as protandric simultaneous hermaphrodite (PSH) [5], i.e., the shrimp first mature as male, and gain female function at a later stage as the shrimp grow, when it remains functional male with gonad produces both eggs and sperms simultaneously
All individuals examined showed ovotestes, which consisted of an anterior ovarian part and a posterior testicular part (Fig 1A)

Summary

Introduction

The vast majority of crustacean species are gonochoristic, the caridean shrimp species belonging to the family Hippolytide display more diverse sexual systems of both gonochorism and hermaphroditism. Ontogenetic development of gonads and external sexual characters of the peppermint shrimp hermaphroditic while T. dobkini and T. floridanus are gonochoristic [1, 2]. All known species from the genus Lysmata have so far been confirmed as protandric simultaneous hermaphrodite (PSH) [5], i.e., the shrimp first mature as male (male phase), and gain female function at a later stage as the shrimp grow, when it remains functional male with gonad produces both eggs and sperms simultaneously (euhermaphrodite phase). There is no study so far tracking ontogenetic gonadal development from newly settled juveniles until they reached euhermaphrodite phase for a Lysmata species

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