Sex steroid profile during oocyte development and maturation in the intertidal worm Marphysa madrasi (Polychaeta: Eunicidae) from the east coast of India.

Marphysa madrasi is a commercially valuable maturation diet in crustacean aquaculture. This study presents the first detailed investigation of oogenesis in the intertidal polychaete worm M. madrasi and reports the steroid profile during oocyte growth and development. Oogenesis is extraovarian type I, originating from coelomic epithelial cells, with four stages of development - primary growth, early vitellogenic, late vitellogenic, and maturation. The primary growth phase contains oogonial cells and previtellogenic oocyte clusters in the early, mid, and late stages of development form a dispersed ovary attached to blood vessels. The late previtellogenic oocytes detach from the ovary at the onset of vitellogenesis. The detached oocytes complete vitellogenesis and final maturation in the coelomic fluid as solitary free-floating cells without any connection with follicle cells. The worms display asynchronous reproduction with a heterogeneous population of developing oocytes. Steroid extracts from the polychaete homogenates in different stages of oogenesis were identified by HPLC and confirmed by LC-MS/MS. In M. madrasi, two vertebrate-type steroids, pregnenolone (P5) and 17α-hydroxyprogesterone (17-OHP) were detected and quantified. The P5 levels were low in immature worms but increased significantly by ∼ 8.3-fold in the previtellogenic stage and peaked during oocyte maturation. 17-OHP levels were low in immature worms but gradually increase as the oogenesis progress to the primary growth and early vitellogenic phase, with a significant increase (p < 0.001) during the late vitellogenic phase. Although an increase in the concentration of P5 and 17-OHP during vitellogenesis and maturation of oocytes points to a possible role in reproduction, the absence of other vertebrate-type steroids in the investigated polychaete signifies a plausible uptake of P5 and 17-OHP from the environment.

A new species of Marphysa (Annelida: Eunicida: Eunicidae) from India, with notes on previously described or reported species from the region.

A new species of Marphysa is described from India using both morphology and molecular data. The new species, Marphysa madrasi, belonging to the Teretiuscula-group, is characterised by having antennae about 2x longer than the prostomium, maxillae II and IV with a relatively large number of teeth (Mx II with 8+9; Mx IV with 7+11), compound spinigers present on a large range of mid-body chaetigers (at least 83-159), and pectinate chaetae present from the first few anterior chaetigers. We discuss all the species of this genus lacking compound falcigers (i.e., those belonging to the Sanguinea-, Mossambica- and Teretiuscula-groups), which have been reported from India and compare them to our new species. Only two accepted species in these groups can be confirmed as occurring in India, M. madrasi n. sp. and M. gravelyi Southern, 1921. We provide a table that summarises the important characters useful to identify species in this group of Marphysa with compound spinigers.