First record of Stibarobdella moorei (Annelida, Hirudinea, Piscicolidae) a marine leech parasitizing Octopus bimaculatus (Mollusca: Octopodidae) from the Mexican Pacific coast

Abstract

SummaryThe occurrence of the parasitic marine leech Stibarobdella moorei (Oka, 1910) (Hirudinea: Piscicolidae) along the northwest Mexican Pacifi c coast is described for the fi rst time. This ectoparasite was collected from the skin of the Octopus bimaculatus (Verril, 1983) (Mollusca: Octopodidae). Stibarobdella loricata (Hardig, 1924) is synonymized with S. moorei as this species resembles other species of the genus based on tubercle patterns and the presence of papillae and a marginal fringe on the oral sucker. The present fi nding throws new light on the biodiversity and host preference of the ectoparasite and suggests a successful migration to unusual host. The coast of the Pacifi c Ocean, particularly in the Bay of Los Angeles, Baja California, Mexico is a new geographical distribution area for S. moorei, and O. bimaculatus is a new host reported for this leech. The morphology of this ectoparasite is briefl y described.

Freshwater mussels house a diverse mussel-associated leech assemblage

“…Although a snail-associated leech assemblage is also poorly known, it seems to be a species-rich entity, with at least eleven leech taxa using freshwater gastropods as hosts only in North America 14 . Stibarobdella moorei , a unique example of a cephalopod-associated marine leech, uses Octopus bimaculatus (Octopodidae) as the primary host 49 . Association of Alboglossiphonia leeches with freshwater bryozoans recorded in Siberia is another unusual example, illustrating a rather “clandestine shelter” commensalism than a host-parasite relationship 50 .…”

“…Mussel-associated leeches ( N = 1,334 specimens) were collected from the mantle cavity of 3,045 freshwater mussels (Unionida: Unionidae, Iridinidae, and Margaritiferidae) using forceps during our broad-scale survey of freshwater mussels in East Asia (Russian Far East, South Korea, and Japan), Southeast Asia (Myanmar) and East Africa (Uganda). For most samples, the number of adult and juvenile leeches (without larvae) in every mussel specimen was recorded (Supplementary Tables 6–7 and 9 and Supplementary Dataset 1) to estimate the prevalence and intensity of leech infestation in each freshwater mussel sample 21,49 . In order to reveal the life cycle of mussel-associated leeches, from every examined mussel specimen we recorded: (1) the presence and position of leeches brooding on the host shell; (2) the presence of mature leeches carrying eggs ( Batracobdelloides ) and those with larvae attached to their abdomen; (3) the presence of leech larvae attached to the host mussel soft body; (4) the presence of juvenile leeches; and (5) the presence of adult leeches (Supplementary Tables 6 and 7).…”

“…Based on our field data (Supplementary Table 9 and Supplementary Dataset 1), the Leech Infestation Prevalence ( LIP , %) index was computed using the following equation:where N IM represents a total number of freshwater mussels infested by at least one leech in a given sample, and N M represents a total number of freshwater mussels in this sample 21,49 .…”

“…The intensity of leech infestation ( ILI , leeches per mussel [l.p.m.]) was calculated using available field data (Supplementary Table 9 and Supplementary Dataset 1) as follows:where ∑ N L represents a total number of leeches collected from the mantle cavity of all freshwater mussels in a given sample, and N M represents a total number of freshwater mussels in this sample 21,49 .…”

First freshwater mussel-associated piscicolid leech from East Asia

“…None of the fish leeches (Piscicolidae) was known to occur in association with freshwater mollusks, although the marine fish leech Pontobdella moorei (Oka, 1910) uses Octopus bimaculatus Verrill, 1883 (Cephalopoda: Octopodidae) as the primary host 7 . This leech family contains numerous marine taxa (including several species discovered from oceanic trenches up to 8.7 km deep 8 ) alongside with a few radiations in fresh water 9 – 11 .…”