New species of Polycystididae (Platyhelminthes: Kalyptorhynchia) from Cuba and the Pacific coast of Panama

Abstract

Four new species of marine polycystidid microturbellarians (Platyhelminthes, Kalyptorhynchia) are described from Cuba and Panama. These species are Brachyrhynchoides ortizi sp. nov., Djeziraia adriani sp. nov., Phonorhynchoides lalanai sp. nov., and Sabulirhynchus ibarrae sp. nov. All species occur in Cuba, and P. lalanai sp. nov. was also retrieved from the Pacific coast of Panama. From the latter locality, we also report Sabulirhynchus axi Artois & Schockaert, 2000. All species are readily distinguished from their congeners by the morphology of the sclerotised structures of the male genital system. The prostatic stylet of B. ortizi sp. nov. is the shortest and widest known for Brachyrhynchoides. Djeziraia adriani sp. nov. can be recognized by its paired seminal vesicles and S-shaped prostate stylet. The prostatic stylet of P. lalanai sp. nov. is proximally twisted and the length proportion between its accessory and prostatic stylet is the largest among all known species of Phonorhynchoides. Sabulirhynchus axi and Sabulirhynchus ibarrae sp. nov. are morphologically similar, yet the latter species is unique due to the characteristic ridge in the middle of the proximally tubular prostatic stylet. With the data available today, a possible explanation of rhabdocoel biogeographic patterns across the Isthmus of Panama remains largely speculative.

First record of a proseriate flatworm predating on a rhabdocoel (Platyhelminthes: Proseriata and Rhabdocoela)

“…As such, we here argue that a deeper exploration of proseriate's ecological role is vital for a holistic understanding of marine ecosystem intricacies. It is also worth mentioning that the proseriate object of this report and presently under study, could not be easily assigned to any known genera and even families of Proseriata and may be taken as explicative of how little is still known about the rich and diverse Cuban meiofauna ( Diez et al 2023 ).…”

“… Phonorhynchopsis haegheni primarily feeds on crustaceans and nematodes, as evidenced by the presence of cuticles from these organisms in its gut (personal observations). With a documented presence in Florida, The Galapagos, Curaçao, Indonesia and Cuba ( Artois and Schockaert 2001 , Diez et al 2018 , Diez et al 2023 , WoRMS 2023 ), it is evident that this species thrives in a wide range of tropical regions. In eastern Cuba specifically, it was previously recorded in the intertidal zones of the North and South coasts, inhabiting areas with salinity levels between 30–35‰ and sediments ranging from coarse to fine sand ( Diez et al 2018 ).…”

“…In eastern Cuba specifically, it was previously recorded in the intertidal zones of the North and South coasts, inhabiting areas with salinity levels between 30–35‰ and sediments ranging from coarse to fine sand ( Diez et al 2018 ). Furthermore, Diez et al (2023) identified numerous specimens of P. haegheni in the same locality where this study was conducted. Considering the similar habitat preferences of the proseriate detailed in this study, encounters between both species are likely to occur.…”