Cardicola milleri Nolan & Cribb 2006, n. sp.

Cardicola milleri n. sp.

(Figs 2–14)

Type host: Lutjanus bohar (Forsskål), Red Bass (Perciformes: Lutjanidae).

Site in host: Atrium and ventricle (heart).

Type locality: Lizard Island, northern Great Barrier Reef (14°40’S 145°27’E), Queensland (QLD).

Material examined: ex L. bohar, Lizard Island (QLD), May 2004, fifteen specimens (QM G 225212–225216) (four specimens used for SEM; another three specimens sequenced for ITS2).

Prevalence of infection: One of two L. bohar from Lizard Island infected with fifteen specimens.

Collector: M.J. Nolan.

Etymology

Specific name for our good friend and colleague Mr Terrence Miller for whom the host fish was originally collected.

Description

Based on eight whole mounts. With features of genus. Body elliptical, 1021–1422 (1305) x 221–379 (335), 3.6–4.6 times longer than wide (Figures 2,6). Tegumental spine rows 13–22 (17) wide; number of spines per row increasing from anterior and posterior ends toward middle of body, 4–6 anteriorly, 7–10 mid­body, 7–4 posteriorly (Figures 7,8). Tegument on ventral surface a series of ridges in maze­like configuration; tegumental papillae ventral, distributed irregularly from inner tegumental spine of each row (Figures 8–10). Nerve chords conspicuous; nerve commissure 105–134 (115) or 8–10% of body length from anterior end. Oral sucker vestigial, reniform to obovate, 18–24 (20) x 13–24 (21), delimited posteriorly by fine membrane, bearing 6–7 concentric rows of fine spines (Figures 3,11,12). Mouth 6–11 (9) from anterior end. Oesophagus sinuous, narrow anteriorly, widening posteriorly, surrounded by gland cells medially and posteriorly, 540–723 (656) or 47–53% of body length. Intestine X­ or H­shaped; anterior caeca unequal, right anterior caecum 115–247 (199) long, left anterior caecum 130–250 (195) long, length 11–18% of body length, irregular in outline, ventral to oesophageal gland cells; posterior caeca sinuous, unequal, right posterior caecum 264–440 (384) long, left posterior caecum 323–520 (438) long, length 31–37% of body length, 1.8–3.3 times longer than anterior pair, posterior extremities expanded. Testis extending anteriorly and laterally to intercaecal field, 315–395 (351) or 24–28% of body length x 138–257 (214) or 55–69% of body width, 1.3–2.0 times longer than wide, containing dorso­ventral muscle fibres. Vas deferens originates anteriorly to posterior margin of testis, passing posteriorly sinuously, ventral to testis, dorsal to left posterior caecum, expanding distally to form seminal vesicle. Seminal vesicle elliptical, 154–193 (174) or 12–15% of body length from posterior end, 96–161 (118) x 16–58 (42), 2.3–6.0 times longer than wide (Figure 4). Ejaculatory duct postero­dorsally directed, sinuous; prostatic cells not seen. Male genital pore surrounded by tegumental papillae (Figure 13). Ovary extending laterally and posteriorly to intercaecal field, extending ventro­anteriorly to posterior margin of testis, 83–167 (127) or 7–13% of body length x 109–221 (189) or 49–64% of body width; 257–331 (305) or 20–29% of body length from posterior end. Oviduct originating at centre of posterior margin of ovary, passing sinistrally then dorso­dextrally, expanding to form oviducal seminal receptacle, narrowing level with anterior margin of seminal vesicle, joining with vitelline duct lateral to anterior margin of seminal vesicle. Oviducal seminal receptacle 64–112 (86) x 22–42 (35), 2.0–2.9 times longer than wide, dorsal to ovary. Vitelline duct seen anterior to posterior margin of testis, passing posteriorly ventral to vas deferens, testis, ovary, oviducal seminal receptacle and oviduct. Oötype lanceolate, lateral to seminal vesicle, 45–74 (63) x 13–22 (20). Mehlis’ gland extends anteriorly to anterior margin of oötype, extending posteriorly past male genital pore. Uterus convoluted, passing latero­sinistrally from oötype, then antero­dextrally to seminal vesicle, level with posterior margin of oviducal seminal receptacle passes sinistrally across midline, dorsal to vitelline reservoir, vas deferens, and posterior margin of ovary, here loops posteriorly to anterior margin of seminal vesicle, then anteriorly to join metraterm (Figure 5). Metraterm muscular, 100–148 (118) x 13–42 (26). Female genital pore sinistral, opening posteriorly to posterior margin of oviducal seminal receptacle and anterior margin of seminal vesicle, antero­dextrally to male pore, surrounded by tegumental folds (Figure 14). Eggs ovoid, 16–32 (22) x 10–26 (16) (n=24). Vitellarium follicular, extending anteriorly to posterior margin of nerve commissure, laterally past the lateral nerve chords, extending posteriorly beyond the posterior margin of ovary, anteriorly dorsal to lateral nerve chords, both dorsal and ventral to oesophagus, intestine and testis, posteriorly ventral to ovary. Excretory vesicle obovate, 6–16 (10) wide; collecting ducts seen extending anteriorly from anterior margin of vesicle. Excretory pore terminal.

Remarks

The new species agrees well with the characters of Cardicola and is here described as a new species in that genus. Cardicola milleri n. sp. differs from existing species in having the combination of a body 1021–1422 (1305) x 221–379 (335) and 3.6–4.6 times longer than wide, an oral sucker, as many as 10 tegumental spines per transverse lateral row, an oesophagus 540–723 (656) long, which is 47–53% of the body length, a testis 315–395 (351) x 138–257 (214) and that extends anteriorly and laterally to the intercaecal field but not posteriorly to it, an ovary 83–167 (127) x 109–221 (189) and is anteriorly intercaecal and which overlaps the posterior margin of the testis and an oviducal seminal receptacle 64–112 (86) x 22–42 (35). The new species also differs in having the male genital pore opening laterally to the oötype and the female pore anterior to it.

The new species most closely resembles C. euzeti n. comb. from the atrium, ventricle and bulbus arteriosus of the heart, and the branchial vessels of the red snapper, Lutjanus campechanus (Poey) (type­host), and the grey snapper, L. griseus (Linnaeus). These species resemble each other (other than in their host distribution) in having a body less than five times longer than wide, the nerve commissure up to 11% of the body length from the anterior end, anterior and posterior caeca extending 7–18% and 23–37% of the body length (respectively), a testis 1.3–2.6 times longer than wide, the ovary length 7–15% of the body length and the ovary width 33–83% of the body width, the oviducal seminal receptacle 2.0–3.1 times longer than wide and the female genital pore opening posterior to the oviducal seminal receptacle.

Cardicola milleri n. sp. differs from C. euzeti n. comb. in the combination of the number of tegumental spines per row, the relative length of the oesophagus, the shape of the intestine, the relative size and distribution of the testis, the relative distance of the seminal vesicle from the posterior end, the position of the male genital pore, the size of the eggs and the distribution of the vitelline follicles. Cardicola euzeti n. comb. has tegumental spines that follow the general pattern 4­5­6­7­6­5­4 along the length of the body, an oesophagus that extends 40–46% of the body length, an intestine that (although sinuous) is regular in outline, and a testis that does not extend anteriorly to the intercaecal field, is 18–25% of the body length and 37–53% of the body width. This species also has the cirrus­sac (described as such by Bullard and Overstreet (2003) but see discussion) 4–11% of the body length from the posterior end, a male genital pore that opens posteriorly to the oötype, uterine eggs 7–12 x 7–10 and vitelline follicles that occupy the space from the posterior margin of the nerve commissure to the anterior margin of the cirrus­sac. In contrast, C. milleri n. sp. possesses tegumental spines in a 4–6: 7–10: 7–4 configuration, an oesophagus that extends 47–53% of the body length, a sinuous and irregularly shaped intestine, and a testis that extends anteriorly and laterally to the intercaecal field, is 24–28% of the body length and 55–69% of the body width. This new species also has the seminal vesicle 12–15% of the body length from the posterior end, a male genital pore that opens laterally to the oötype, uterine eggs 16–32 (22) x 10–26 (16) and a vitelline follicle distribution that occupies the space from the posterior margin of the nerve commissure to the posterior margin of the ovary.