Abstract
We examined the host specificity of two ectosymbiotic Clausidium Kossman, 1874 copepods (Cyclopoida: Clausiididae) on two co‐occurrence species of host ghost shrimps. Our results revealed that both species of symbiotic copepod demonstrated extremely high host specificity. Moreover, within a single host shrimp species, each symbiont species displayed strong spatial patterns in microhabitat selection on their hosts’ bodies. Clausidium persiaensis Sepahvand & Kihara, 2017, was only found on the host Callianidea typa Milne Edwards, 1837 and almost exclusively within the host shrimp gill chamber, while C. iranensis Sepahvand, Kihara, & Boxshall, 2019 was only found on the host Neocallichirus jousseaumei (Nobili, 1904) and showed extremely strong preferences for the chelae and anterior walking legs. We also found that while the number of symbionts tends to increase with the host size, the two host species differed in the degree of symbiont infestation, with large C. typa hosting approximately 7× as many symbionts as the similarly sized N. jousseaumeia. The mechanisms resulting in the observed differences in infestation levels and microhabitat preferences of clausidium copepods among their hosts, including differences in physiology, burrowing pattern, and host grooming behavior should be further investigated.
Highlights
Recent studies have revealed the ubiquitous nature of symbiotic relationships
The ghost shrimp fauna at the site was dominated by Neocallichirus jousseaumei and Callianidea typa Milne Edwards, 1837 that supported the populations of the symbiotic copepods Clausidium iranensis Sepahvand et al, 2019 (Figure 1) and Clausidium persiaensis Sepahvand and Kiahara, 2017 (Figure 2)
We discovered two co-occurrence species of ghost shrimp, Neocallichirus jousseaumei (Nobili, 1904) and Callianidea typa, Milne Edwards, 1837 that served as hosts to copepod symbionts
Summary
Recent studies have revealed the ubiquitous nature of symbiotic relationships. While the majority of symbiotic relationships involve associations between organisms of disparate size, usually a larger host with a smaller symbiont, the degree of host specificity found among symbionts is remarkably variable. Marin and Nascimento (1993) analyzed the body size and habitat of Callichirus garthi (Retamal, 1975) (Decapoda: Callichiridae) as the factors affecting the distribution, abundance, and fecundity of their symbiotic copepods (Clausidium spp.). They (Marin & Nascimento, 1993) suggested that the density of Clausidium spp. per host was dependent upon host habitat type and recruitment. Corsetti and Strasser (2003) examined host selection of Clausidium dissimile Wilson, 1921 in two co-occurrence populations of ghost shrimps They found that, host-size adjusted density of C. dissimile was affected by the host species and the months sampled.
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