Atopogyrodactylus praecipuus, Kritsky & Boeger & Patella, 2020

Kritsky, Delane C., Boeger, Walter A. & Patella, Luciana, 2020, Neotropical Monogenoidea. 63. Atopogyrodactylus praecipuus gen. et sp. n. (Gyrodactylidae), an oviparous gyrodactylid from the external surface of a bristlenose catfish Ancistrus sp. (Siluriformes: Loricariidae) from the Rondônian Amazon, Brazil, Zootaxa 4732 (1), pp. 169-176 : 171-175

Atopogyrodactylus praecipuus n. sp.

( Figs. 1–10 )

Type-host: Bristlenose catfish, Ancistrus sp. ( Loricariidae ).

Type-locality: Headwaters of the Rio Candeias south of Campo Novo de Rondônia and Road BR421, Rondônia, Brazil (10°49’8.67” S, 63°37’31.16” W to 10°47’12.35” S, 63°37’31.16” W), 15 December 2013.

Site on host: External surface.

Type specimens: Holotype, IOC 40095; 14 paratypes, IOC 40095, 40096 , 40097 , HWML 216037 ; 14 remaining paratypes in collection of WAB.

Etymology: The specific name (an adjective) is derived from Latin ( praecipuus = peculiar, special, or extraordinary).

ZooBank registration: The Life Science Identifier (LSID) for Atopogyrodactylus praecipuus n. sp. is urn:lsid:zoobank.org:act:549E2EBC-6063-48A3-AC2B-611ACFD54480 .

Description: Greatest body width in anterior trunk at level of germarium; peduncle elongate, slender, slightly tapered posteriorly. Cephalic lobes moderately developed; head organs conspicuous. Testis subspherical to subovate; anterior seminal vesicle slightly smaller than posterior vesicle. Copulatory sac absent; MCO usually shaped as an inverted U. Accessory copulatory sclerite rod-shaped, subterminally expanded, with terminal spine. Germarium subspherical, with germinal cells surrounding distinct fertilization chamber; fertilization chamber containing oocyte. Oviduct with comparatively thick wall—often appearing sclerotized; Mehlis’ gland well developed, surrounding ootype; uterus containing a maximum of 1 egg; uterine pore lying to right of MCO, a transverse to diagonal slit with thickened rim. Proximal egg filament short, flared, about 1/10 total egg length; egg droplet prominent, an amorphous mass surrounding egg filament. Haptor cup shaped; anchor delicate, lacking well-defined basal roots, with tapered shaft, elongate recurved point; ventral haptoral plate ovoid, with thickened rim. Hook shank tapered to fine proximal ligament, lacking keel; hooklet flexed ventrally, with fine elongate closed point, ventrally leaning shaft, globose heel, truncate toe; FH loop about 1/4 shank length.

Measurements: Measurements of immature specimens follow those of the adults in brackets, respectively. Body 1,310 (968–1,530; n = 3) [706 (467–895; n = 10)] long; width 118 (116–123; n = 3) [83 (66–105; n = 10)] at level of germarium. Posterior pharyngeal bulb 59 (53–63; n = 3) [41 (35–49; n = 8)] wide; anterior pharyngeal bulb 45 (35–50; n = 3) [36 (31–45; n = 8)] wide. Accessory copulatory sclerite 30–31 (n = 1) [32 (28–35; n = 2)] long. Haptor 49 (41–57; n = 7) [42 (37–47; n = 7)] long, 50 (42–59; n = 5) [43 (39–55; n = 7)] wide. Ventral haptoral plate 32 (26–38; n = 5) [28 (24–36; n = 10)] long, 22 (18–29; n = 4) [21 (18–23; n = 7)] wide. Anchor 21 (17–23; n = 3) [17 (16–18; n = 9)] long. Hook 27–28 (n = 3) [27 (26–31; n = 11)] long; hooklet 5 (4–6; n = 3) [5 (4–6; n = 19)] long. Germarium 65 (49–80; n = 2) in diameter; testis [57 (49–69; n = 9)] long, [49 (38–62; n = 9)] wide. Egg 201 (192–207; n = 3) long, 66 (53–80; n = 3) wide.

Remarks: Atopogyrodactylus praecipuus n. sp. is the type species and currently the only member assigned to the genus.

Figures

FIGURES 1–10. Atopogyrodactylus praecipuus n. gen., n. sp. from the external surface of a bristlenose catfish, Ancistrus sp. in Brazil. 1. Whole mount of adult, composite, ventral view. 2, 3. Accessory copulatory sclerites. 4. Terminal genitalia (male and female) of an immature specimen. 5. Whole mount of immature specimen (composite, ventral view). 6. Hook. 7. Egg. 8. Oviduct. 9. Anchor. 10. Haptor. Abbreviations: mco, male copulatory organ; as, accessory copulatory sclerite; vit, vitelline follicle; g, germarium; sv, seminal vesicle; ov, oviduct; c, cecum.