Lintaxininae Price, 1962

Kamio, Yusuke, Yamamoto, Kanna & Nitta, Masato, 2024, Redescription of Bicotyle reticulata (Monogenea: Heteraxinidae) from Pampus punctatissimus (Scombriformes: Stromateidae) in the Seto Inland Sea, Japan, Species Diversity 29 (1), pp. 151-160 : 154-157

publication ID	https://doi.org/ 10.12782/specdiv.29.151
persistent identifier	https://treatment.plazi.org/id/03A3879F-8809-FFC9-272F-9198FC2AFB61
treatment provided by	Felipe
scientific name	Lintaxininae Price, 1962
status

Treatment

Subfamily Lintaxininae Price, 1962 Genus Bicotyle Tripathi, 1956 Bicotyle reticulata ( Goto, 1894) ( Figs 1–4 View Fig View Fig View Fig View Fig )

Microcotyle reticulata Goto, 1894: 189–191 , pl. 1, fig. 5, pl. 3, figs 2–4, pl. 4, figs 2, 3, pl. 5, figs 5, 6; Meserve 1938: 52; Yamaguti 1943: 21; Sproston 1946: 439; Bychowsky 1957: 48, 423, fig. 66; Inaba 1988: 239.

Bicotyle reticulata View in CoL : Tripathi 1956: 236; Price 1962: 416; Yamaguti 1963: 266; Lebedev 1968: 45; Mamaev 1990: 227; Nitta and Nagasawa 2015: 124; Nitta et al. 2022: 590.

Dictydenteron reticulatum View in CoL : Unnithan 1961: 126 (generic name unavailable).

Dictydenteron reticulatum View in CoL : Unnithan 1971b: 46 (generic name available); Unnithan 1971a: 397.

Redescription. Body fusiform 10900–25225 (19565, n = 15) long including haptor, 1400–4850 (3656, n = 13) wide at level of germarium ( Fig. 1 View Fig ). Haptor wedge-shaped, symmetrical, 2075–4950 (3815, n = 13) long, 3100–8575 (6337, n = 13) wide, armed with clamps of unequal structure and number on the two sides ( Fig. 1 View Fig ). Clamps ( Fig. 2A View Fig ) on right side, typical Microcotyle - type, each clamp 30–54 (47, n = 15) in number, 40–700 (123, n = 17) long, 60–340 (158, n = 17) wide; posterolateral sclerite and anterolateral sclerites curved toward inside; dorsal mid-sclerite short, ventral mid-sclerite long, both mid-sclerites bifurcated on top; small sclerites from proximal end of anterolateral sclerite toward inside. Clamps ( Fig. 2B View Fig ) on left side, large, each clamp 13–25 (22, n = 15) in number, 45–390 (179, n = 17) long, 80–450 (247, n = 17) wide, consisting of two pairs of lateral sclerites and 2 mid-sclerites; posterolateral sclerite Ushaped, bordering lateral portion of posterior half of clamp; anterolateral sclerite curved, bordering lateral portion of anterior half of clamp; dorsal mid-sclerite long, tuning fork shaped on tip; ventral mid-sclerite short, bifurcated on top.

Mouth terminal. Pair of buccal suckers ( Figs 1 View Fig , 2C View Fig ) circular 35–115 × 30–90 (87 × 76, n = 12). Pharynx subspherical ( Figs 1 View Fig , 2C View Fig ), lying behind buccal sucker 310–495 × 210–295 (415 × 248, n = 11). Esophagus narrow ( Figs 1 View Fig , 2C View Fig ), with lateral diverticula, connecting intestinal ceca, bifurcating anterior to the male genital pore. Intestinal ceca blind, extending to base of haptor, having dark pigment granules in anteri- or part of body. The branches of the intestinal ceca form a complicated network ( Figs 1 View Fig , 4 View Fig ).

Testes with irregular shape ( Figs 1 View Fig , 3 View Fig ), 126–323 (217, n = 8) in number, postovarian, arranged in the posterior half of body and confined to intercrural field. Vas deferens long, coming from anterior of testes in middle of body at level posterior of oötype, ventral to germarium, extending forward along body midline, entering base of genital atrium ( Figs 1 View Fig , 2D View Fig , 3 View Fig ). Genital atrium tubular shape, located 80–135 (105, n = 12) long from posterior to intestinal bifurcation, armed with 16–169 (59, n = 10) spines, arising from muscular cushion ( Figs 1 View Fig , 2D View Fig ).

Germarium beginning at center of body, expanding to posterior of right side of body extending from right to left side, curved anteriorly then returned to right side of body and then extended toward oviduct ( Figs 1 View Fig , 3 View Fig ). Oviduct arising from distal end of germarium and opening into genito-intestinal canal ( Figs 1 View Fig , 2D View Fig , 3 View Fig ). Genito-intestinal canal originates from right intestinal cecum and bifurcates into oötype and vitelline duct ( Fig. 3 View Fig ). Vitelline duct Y-shaped, ventral, extending from genito-intestinal canal and bifurcating to either side in posterior part of the germarium ( Figs 1 View Fig , 3 View Fig ). Oötype extending from genito-intestinal canal to uterus with numerous Mehlis’ glands ( Fig. 3 View Fig ). Uterus originating from oötype, extending anteriorly along body midline, ventral to vas deferens, to the opening of the genital atrium ( Figs 1 View Fig , 2D View Fig , 3 View Fig ). Vaginal pore funnel-shaped, armed with conical spines, dorsal in mid-body, posterior to genital atrium ( Figs 1 View Fig , 2E View Fig ). Vaginal duct dorsal to uterus and vas deferens, cuticle uneven, bifurcating posterior to vaginal pore, connecting to oötype ( Figs 1 View Fig , 2E View Fig , 3 View Fig ). Eggs fusiform 220 × 85 (n = 1) excluding filament, with filaments at both ends broken. Vitelline follicles extending from behind genital atrium to posterior end of body, fused posterior to testes ( Fig. 1 View Fig ).

Material examined. Seven, four, and four monogenean specimens from the Seto Inland Sea off Imabari City ( MPM Coll.-Nos 25261, 25262, MNHN HEL2058, 2059), off Tatsugahama, Arita City ( MPM Coll.-No. 25263), and near Matsuyama City ( MPM Coll.-No. 25264, MNHN HEL2060, 2061), respectively.

Localities. The Seto Inland Sea, off Imabari City (Hiuchi-nada), and Matsuyama City, in Ehime Prefecture, and off Tatsugahama, Arita City, Wakayama Prefecture, Japan .

Host. Pampus punctatissimus (Temminck and Schlegel, 1845) ( Perciformes : Stromateidae ).

Site of infection. Gill filaments.

Representative DNA sequences. The 28S rDNA sequence (862 bp) was deposited by Nitta et al. (2022) under INSD accession number LC664020. The sequences were obtained from a specimen collected from the Seto Inland Sea off Imabari City (MPM Coll.-No. 25261). A newly obtained 28S rDNA sequence (976 bp) from a specimen collected from the Seto Inland Sea off Matsuyama City (MPM Coll.- No. 25264) was deposited under INSD accession number LC773706.

Remarks. The present specimens collected from P. punctatissimus in the Seto Inland Sea confirm to the descriptions and illustrations of B. reticulata by Goto (1894). However, the length of the body is longer than Goto’s measurements. Additionally, the number of genital spines shows a wide range (16–169, mean: 54) and is different from the original description. However, these differences may be due to intraspecific variation because the other diagnostic morphological characteristics of our specimens agree well with the descriptions of B. reticulata by Goto (1894). The vaginal duct of the newly collected specimens possesses an uneven inside that was not mentioned nor illustrated in the original description ( Fig. 3 View Fig ). The clamps on the right side have been stated as smaller and more numerous than the clamps on the left side ( Goto 1894), but the present study has revealed that the structure of the clamps also differs between the left and right sides.

Bicotyle reticulata differs from its congeners by the presence of spines in the vaginal pore and vaginal duct bifurcation, except for B. chongwuensis Ding and Zhang, 1995 ( Tripathi 1956; Lebedev 1968; Kotwal and Masurekar 1978; Agrawal and Sharma 1990; Ding and Zhang 1995). Nevertheless, the number of genital spines in the genital atrium distinguishes B. reticulata from B. chongwuensis (16–169 in B. reticulata vs. 10–14 in B. chongwuensis ).

Goto (1894) reported the type host of B. reticulata as silver pomfret Stromateus argenteus . However, S. argenteus (= P. argenteus ) is not distributed in the Seto Inland Sea, and P. punctatissimus is the only species of the genus distributed in the sea ( Nakabo 2013). Thus, the type host of B. reticulata is redefined as P. punctatissimus .

Molecular data analysis. The trimmed multiple sequence alignment length of the 28S rDNA fragments consisted of 840 base pairs including gaps. The topologies of each phylogenic tree constructed by ML and BI analyses were almost identical, and the phylogenetic trees based on BI analysis are shown in Fig. 5 View Fig . The clade is separated into two groups, one consisting of the Heteraxinidae , Microcotylidae and Heteromicrocotylidae and the other comprised of Macrovalvitrematidae and Diclidophoridae . Bicotyle reticulata and the other 5 species of Heteraxinidae constituted a monophyletic group, but Heteromicrocotylidae was shown as non-monophyletic and Heteromicrocotyla polyorchis Unnithan, 1961 ( Heteromicrocotylidae ) formed a sister group with Heteraxinidae .