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Hogfish Lachnolaimus maximus (Walbaum, 1792) is the largest labrid in the Atlantic and a commercially important fish. In previous research, this fish has been defined as a monandric protogynous hermaphrodite, although characterization of hermaphroditism is particularly challenging in labrids. Examination of testicle structure is not always a wholly trustworthy method for distinguishing between diandric species (those with primary and secondary males) and monandric species (only secondary males). In some diandric species, morphological differences in the testes do not occur between primary and secondary males despite functional diandry. The presence of individuals with inactive bisexual gonads and/or of inactive males smaller than the minimum size of sexual maturation is a more dependable criterion for identifying diandry. A histological analysis of the gonads of 1,975 L. maximus specimens (10.3-47.4 cm fork length, FL ) from the southern Gulf of Mexico was done. Some individuals were identified that were larger than the size at first maturity (N = 20,24.8-33.5 cm FL) and had ovotestes atypical of a monandric species. These ovotestes had an internal morphology like ovaries, consisting mostly of inactive ovary tissue in lamellar structure, as well as limited development of active testicular tissue in crypts inside the gonad wall and/or in lobules beneath the gonad wall. Considered to be “bisexual" gonads, their origin and function were evaluated based on published data. Lachnolaimus maximus could be defined as a diandric species if males can differentiate indirectly by sexual inversion of functional females (postmaturational secondary males) or by direct development from the “bisexual" stage (prematurational secondary males). However, no inactive bisexual individuals or inactive males smaller than the size at first maturity were observed. In addition, population structure and overall sex ratio were typical of a monandric protogynous species. The possibility that L. maximus could exhibit diandric hermaphroditism therefore remains hypothetical. [ABSTRACT FROM AUTHOR]

Diagnosing hermaphroditism in teleost fish requires careful assessment and is particularly challenging in groupers. Established, reliable criteria to detect functional protogynous hermaphroditism were used to collect data on sexual pattern in six minimally studied grouper populations on the continental shelf of the Yucatan Peninsula. Individuals in the process of changing sex (transitional individuals), considered strongly indicative of protogyny, were observed. Functional protogynous hermaphroditism was confirmed for Epinephelus morio (Valenciennes, 1828) and Mycteroperca venenosa (linnaeus, 1758), and for populations of Epinephelus guttatus (linnaeus, 1758), Mycteroperca bonaci (Poey, 1860) and Mycteroperca tigris (Valenciennes, 1833) from the southern gulf of Mexico. Although Mycteroperca microlepis (Goode & Bean, 1880) has been confirmed as pro-togynic in previous studies, distinctive transitional individuals were not identified in the analysed sample. Transitional individual rates were low in the studied sample: 1.0% for E. morio; 0.5% for E. guttatus and M. bonaci; 0.6% for M. tigris; and 0.2% for M. venenosa. Timing of sex change in these grouper species did not exhibit any seasonal pattern. For E. morio, M. bonaci and M. microlepis, the lack of primary males or bisexual individuals among juveniles collected from inshore waters, and the presence of morphological features characteristic of secondary males in testes from adults collected from offshore waters, suggest monandry in the southern gulf of Mexico populations of these three species. [ABSTRACT FROM AUTHOR]