Another brick in the wall: population dynamics of a symbiotic species of Oxydromus (Annelida, Hesionidae), described as new based on morphometry

Oxydromus humesi is an annelid polychaete living as a strict bivalve endosymbiont (likely parasitic) of Tellina nymphalis in Congolese mangrove swamps and of Scrobicularia plana and Macomopsis pellucida in Iberian saltmarshes. The Congolese and Iberian polychaete populations were previously consider...

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Bibliographic Details
Published in:Contributions to zoology (Amsterdam, Netherlands : 1995) Netherlands : 1995), 2017-10, Vol.86 (3), p.181-211
Main Authors: Martin, Daniel, Meca, Miguel A, Gil, João, Drake, Pilar, Nygren, Arne
Format: Article
Language:English
Subjects:
Aggressive behavior
Appendages
Fertilization
Hesionidae
Mangrove swamps
Morphometry
New species
Population dynamics
Seasonal variations
Swamps
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Summary:Oxydromus humesi is an annelid polychaete living as a strict bivalve endosymbiont (likely parasitic) of Tellina nymphalis in Congolese mangrove swamps and of Scrobicularia plana and Macomopsis pellucida in Iberian saltmarshes. The Congolese and Iberian polychaete populations were previously considered as belonging to the same species, the latter showing regular distribution, intra-specific aggressive behaviour, and complex hostentering behaviour. The fresh Iberian samples enabled us to undertake consistent morphometric analyses, as well as to further analyse the characteristics of the association and the population dynamics of the Iberian population hosted by S. plana. Among the morphological differences between the Congolese and Iberian specimens, leading to the description of the latter as Oxydromus okupa sp. nov., the most important are: 1) longer cephalic appendages, 2) greater distance between the eyes, 3) larger dorsal cirrostyle in relation to the corresponding dorsal lobe and cirrophore. Moreover, dorsal and ventral lobes are similar in length, with the tip of the former reaching the tip of the latter in O. okupa sp. nov., while the dorsal lobe is much shorter than the ventral one in O. humesi. Mature adults of O. okupa sp. nov. occurred during the whole study period, with a higher percentage of ripe females in spring and, particularly, in summer. Numerous host specimens showed the symbiont’s most preferred shell length (>26 - 36 mm). However, the prevalence was very low (usually
ISSN:1383-4517
1875-9866
1383-4517
DOI:10.1163/18759866-08603001