Subterranean Fishes of the World

Country

Types

Only a Holotype has been assigned: MNHN 1922-0002.

Biological Notes

Liem (1968) studied the types of sexuality in Synbranchiformes. Of Typhlosynbranchus bouetti he says: "The ovary of Typhlosynbranchus has a similar lamellar organization as that of Synbranchus rnarrnoratus. However, no intermediate intersexual gonad has been found among the nine specimens. Females are recorded with total lengths of 17.5, 18.5 and 20.5 cm. The males measured 19.5, 26.5, 27.5, 30.0 and 34 cm in total length. Bilobular and pure testes were found in the smallest male, while the four larger males had testes with a lamellar organization and some remnants of degenerated oocytes. Based on two histologically distinguishable types of males, I may conclude that protogynous hermaphroditism does occur in Typhlosynbranchus."

Sadovy de Mitcheson and Liu (2008) elabotate as follows: "Protogyny is confirmed in three genera, Monopterus albus (=Fluta alba, Monopterus javanensis), M. boueti (=Typhlosynbranchus boueti), Ophisternon bengalense (=Synbranchus bengalensis) and Synbranchus marmoratus, with both gonochorism and protogyny occurring in Monopterus (Table 1). Two different testicular morphologies suggest two male developmental pathways, indicating diandry in these species (Liem 1968; Lo Nostro and Guerrero 1996). The ovary is unusual in being a single lobe surrounded by a thick connective tissue tunica; two ovarian lamellae fold to form two ovarian cavities, suspended within the cavity into which mature oocytes are released (Okada 1966a; Liem 1968). Testes of secondary males retain the lamellar organization from the female phase. Ovarian tissue in the outer half of the lamellae degenerates during sexual transition (Okada 1966a; Chan and Phillips 1967; Liem 1968; Lo Nostro and Guerrero 1996). The two ovarian cavities do not function for sperm release; instead, a new sperm duct system develops within the lamellae (Lo Nostro and Guerrero 1996). Testes of primary males consist of a pair of solid lobes and exhibit no ovarian lamellar organization (Liem 1968; Lo Nostro and Guerrero 1996)."

Museum Holdings

MCZ unknown accession number serially sectioned head