Renicola

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 : 487-488

Renicola sp. “polychaetophila” (sensu Hechinger and Miura [2014])

(17. Repo; Figs. 1 , 71–74 )

Diagnosis: Parthenitae. Colony comprised of inactive sporocysts, densely concentrated to irregularly clustered in snail gonad region, with dispersion into digestive gland. Sporocysts translucent orange to white; ~ 100–800 µm long, spheroidal to slightly elongate (length:width up to ~4:1).

Cercaria . Body mostly opaque white; non-oculate; with oral and ventral sucker; with no tegumental spines; with penetration gland duct opening arrangement of 2[(1+3+1)+1], with 3 pairs opening adjacent to oral stylet, 1 diverging to open more dorsally, 1 ventrally, with 1 separated pair forming characteristic ventral “cross ducts” posterior to oral sucker; with a large Y-shaped excretory bladder, the arms of which wrap around sides of ventral sucker; body ~ 180 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: Repo is most readily distinguished from Rema [16] by the cercaria penetration gland duct arrangement (particularly the posterior-most “cross ducts”) and lack of tegumental spines.

Remarks: Hechinger and Miura (2014) described the sporocysts and cercariae, and provided COI and ITS1 DNA sequence data.

This species was not included in Martin (1972), but specimens of it may have been included, along with specimens of Renicola cerithidicola in the material Hunter (1942) used to describe her “ Cercaria cerithidia 19” ( Hechinger & Miura 2014). This species, along with Renicola sp. “martini” was previously referred to as “large xiphidiocercaria” in some ecological and evolutionary research (e.g., Hechinger et al. 2007; Kuris 1990).

Mature, ripe colonies comprise ~20% the soft-tissue weight of an infected snail (summer-time estimate derived from information on “lgxi” in [ Hechinger et al. 2009]).

Nadakal (1960b) presents information on the pigments of the sporocysts and cercariae of this species (likely pooled with Renicola sp. “martini”), as his “Y-bladder cercaria”.

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 71–74. Renicola sp. “polychaetophila” (Repo). 71, Overview of a colony in a freshly deshelled, infected horn snail in sea water. Arrow indicates the colony, which is localized in the gonadal region with infiltration of the digestive gland. Scale bar = 1 cm. Photo from Hechinger & Miura (2014). 72, Sporocysts, live, with developing cercariae, under coverslip pressure. Scale bar = 100 µm. 73, Cercaria, live, under coverslip pressure. Scale bar = 100 µm. 74, Close-up of cercaria anterior end, heavy coverslip pressure, oral stylet visible, as are dorsal penetration duct openings and posterior-ventral “cross ducts” (white arrows). Scale bar = 10 µm.