NEW SPECIES OF AXINE ABILDGAARD, 1794 (MONOGENOIDEA: AXINIDAE) INFECTING GILL LAMELLAE OF ATLANTIC FLYINGFISH, CHEILOPOGON MELANURUS (VALENCIENNES) (EXOCOETIDAE) IN THE WESTERN ATLANTIC OCEAN WITH PHYLOGENETIC ANALYSIS AND COMMENTS ON THE FEMALE GENITALIA OF AXINE SPP.
We collected specimens of Axine trickyvagina Brule and Bullard n. sp. (Monogenoidea: Axinidae) from the gill lamellae of Atlantic flyingfish, Cheilopogon melanurus (Valenciennes) (Exocoetidae) in the north-central Gulf of America. Specimens of the new species were heat-killed and formalin-fixed for morphology, and others were preserved in 95% EtOH for DNA extraction and sequencing of the 28S gene and ITS1 region. The new species differs from all congeners by the combination of having a long haptor (∼40–50% of the total body length), a male copulatory organ with 10–15 spines, and a genital atrium having bilateral spinous patches each with 18–25 spines. Our study of specimens of the new species, type and voucher specimens representing 8 congeners, and all published accounts of all congeners revealed that the terminal female genitalia of Axine spp. comprises 2 ducts (a multi-chambered vagina that lacks a sclerite plus an accessory duct with a sclerotized nozzle comprising its opening) that open into a common female genital atrium. Descriptions of Axine spp. published from 1794 through 2023 failed to recognize the vaginal duct and accessory duct as distinct components and unanimously misinterpreted the accessory duct’s sclerotized nozzle as a “vaginal spine.” The phylogenetic analysis inferred from 28S rDNA sequences placed our sequence in a clade of other Mazocraeidea spp. and sister to a nonugen sequence ascribed to Axine japonicaPrice, 1946 (GenBank LC799038). We recovered Axinidae as sister to Heteromicrocotylidae, Heteraxinidae, and Microcotylidae. The present study is the first published description of an axinid from a flyingfish in the western Atlantic Ocean.ABSTRACT
Axine trickyvagina n. sp. (Monogenoidea: Axinidae) from gill lamellae of Atlantic flyingfish, Cheilopogon melanurus (Valenciennes) (Beloniformes: Exocoetidae) from the northern Gulf of America. Scale value aside bar. Ventral view of whole body of holotype (USNM 1754239). The arrow indicates the location of the haptoral lappet. Abbreviations: bs, buccal sucker; c, clamp; e, esophagus; ep, excretory pore; ga, genital atrium; gc, genito-intestinal canal; in, intestinal cecum; nc, nerve cord; o, ovary; oö, oötype; osr, oviductal seminal receptacle; ovd, ovo-vitelline duct; p, pharynx; t, testis; tfg, terminal female genitalia; u, uterus; vd, vas deferens; vi, vitellaria.
Axine trickyvagina n. sp. (Monogenoidea: Axinidae) from gill lamellae of Atlantic flyingfish, Cheilopogon melanurus (Valenciennes) (Beloniformes: Exocoetidae) from the northern Gulf of America. Scale value aside bar. Ventral view of anterior end of holotype (USNM 1754239). Abbreviations: bs, buccal sucker; e, esophagus; m, mouth; nc, nerve cord; p, pharynx; ts, terminal sucker.
Axine trickyvagina n. sp. (Monogenoidea: Axinidae) from gill lamellae of Atlantic flyingfish, Cheilopogon melanurus (Valenciennes) (Beloniformes: Exocoetidae) from the northern Gulf of America. Scale values aside bars. Ventral views unless otherwise noted. (3) Clamp of holotype (USNM 1754239). (4) Crochet en fléau of paratype (USNM 1754242) dorsal view. (5) Anchor of holotype (USNM 1754239). (6) Hook of paratype (USNM 1754242) dorsal view. Abbreviations: ap, accessory piece; dds, distal dorsolateral sclerite; ms, median sclerite; pds, proximal dorsolateral sclerite; s, spur; tw, twist; vls, ventrolateral sclerite.
Axine trickyvagina n. sp. (Monogenoidea: Axinidae) from gill lamellae of Atlantic flyingfish, Cheilopogon melanurus (Valenciennes) (Beloniformes: Exocoetidae) from the northern Gulf of America. Scale values aside bars. All ventral views. (7) Male reproductive genitalia (ovary shown) of holotype (USNM 1754239). (8) Genital atrium of holotype (USNM 1754239). Abbreviations: dsp, dextral spinous patch; ga, genital atrium; gp, common genital pore; gr, granular portion; mco, male copulatory organ; msp, median spinous patch; o, ovary; ssp, sinistral spinous patch; t, testis; vd, vas deferens.
Axine trickyvagina n. sp. (Monogenoidea: Axinidae) from gill lamellae of Atlantic flyingfish, Cheilopogon melanurus (Valenciennes) (Beloniformes: Exocoetidae) from the northern Gulf of America. Scale values aside bars. All ventral views. (9) Female reproductive genitalia (male copulatory organ not drawn) of holotype (USNM 1754239). (10) Terminal female genitalia of holotype (USNM 1754239). (11) Egg of holotype (USNM 1754239). Abbreviations: ad, accessory duct; adn, accessory duct nozzle; cfga, common female genital atrium; dc, distal capsule; dv, distal vagina; fc, follicular chamber; ga, genital atrium; gc, genito-intestinal canal; gf, glandular field; in, intestinal cecum; o, ovary; od, oviduct; oö, oötype; osr, oviductal seminal receptacle; ovd, ovo-vitelline duct; pv, proximal vagina; sc, spermatophore chamber; sp, spermatophore; tfg, terminal female genitalia; tvd, transverse vitelline duct; u, uterus; v, vaginal duct.
28S phylogeny. Values aside nodes are bootstrap values. Scale bar is in substitutions per site. GenBank numbers are in parentheses following each taxon, with nonugens indicated by quotation marks. Bars with family names indicate monophyly. Bold text indicates the sequence of Axine trickyvagina n. sp.
Contributor Notes
Version of Record, first published online with fixed content and layout, in compliance with ICZN Arts. 8.1.3.2, 8.5, and 21.8.2 as amended, 2012. ZooBank publication registration: urn:lsid:zoobank.org:pub:D08AF1FE-EEBA-4982-9132-5F3525AF96D5.