Renicola cerithidicola Martin, 1971

Hechinger, Ryan F., 2019, Guide to the trematodes (Platyhelminthes) that infect the California horn snail (Cerithideopsis californica: Potamididae: Gastropoda) as first intermediate host, Zootaxa 4711 (3), pp. 459-494 : 485

Renicola cerithidicola Martin

(15. Rece; Figs. 1 , 61–64 )

Diagnosis: Parthenitae. Colony comprised of inactive sporocysts, densely concentrated in snail mantle (in enlarged perirectal sinus). Sporocysts translucent yellow, orange, sometimes white; ~ 500–1500 µm long, ovoid to elongate (length:width up to ~6:1), ~sausage-shaped.

Cercaria . Body mostly opaque white; non-oculate; with oral and ventral sucker; with a large Y-shaped excretory bladder, the arms of which wrap around sides of ventral sucker; body ~ 117 µm long, ~equal in length to tail; tail simple.

Cercaria behavior: Fresh, emerged cercariae remain in water column, swim ~continuously, lashing tail back and forth.

Similar species: Rece is readily distinguished from the two other small renicolid cercariae (Rema [16] and Repo [17]) by its lack of an oral stylet and by the colony locus being in the mantle.

Remarks: Martin (1971) described this species based on the sporocysts, cercariae, and experimentally obtained metacercariae (he was able to get only immature adult specimens in young California gulls). Hechinger and Miura (2014) provided COI and ITS1 DNA sequence data for this species.

Specimens of this species may have been included, along with specimens of Renicola sp. “polychaetophila”, in the material Hunter (1942) used to describe her “ Cercaria cerithidia 19” ( Hechinger & Miura 2014). This species corresponds to the “Y-bladder cercaria” of Martin (1955).

Early Rece infections can be detected. The sporocysts appear to typically initially form in the basal visceral mass, as generally expected for species that infects the snail with ingested eggs ( Galaktionov & Dobrovolskij 2003) (unpublished observations).

Mature, ripe colonies comprise ~17% the soft-tissue weight of an infected snail (summer-time estimate derived from information in [ Hechinger et al. 2009]).

Rece infection causes (stolen) snail bodies to grow ~ 2x faster than uninfected snails ( Hechinger 2010).

Figures

FIGURE 1. General characteristics of the parthenitae and cercariae of the trematodes infecting Cerithideopsis californica as first intermediate host. Species numbers and codes follow Table 1 and species accounts. Cercariae are all to scale, with additional magnified views of six small species (indicated by dashed lines). Note the oral stylets (presented in right lateral view) for Pruc and Smmi. Parthenitae are not to scale. Scale bars consistently indicate 100 µm.

FIGURES 61–64. Renicola cerithidicola (Rece). 61, Overview of a colony in a freshly deshelled, infected horn snail in sea water. Arrow indicates the colony, which is localized in the mantle. Scale bar = 1 cm. Base photo credit: Andrew Turner. 62, Sporocysts, live, with developing cercariae, under heavy coverslip pressure. Note the paletot surrounding each sporocyst’s tegument. Scale bar = 500 µm. 63, Cercaria, live, under coverslip pressure. Scale bar = 100 µm. Ocular micrometer hatch mark = 2.5. 64, Same cercaria as 63, but with a different focal plane, highlighting the Y-shaped excretory bladder. Scale bar = 100 µm. Ocular micrometer hatch mark = 2.5.