Natterophthalmus andersoni Dronen & Penner, 1975

Dronen, Norman O., Blend, Charles K., Gardner, Scott L. & Jiménez, F. Agustín, 2007, Stictodora cablei n. sp. (Digenea: Heterophyidae) from the royal tern, Sterna maxima (Laridae: Sterninae) from Puerto Rico and the Brazos County area of the Texas Gulf coast, U. S. A., with a list of other endohelminths recovered in Texas, Zootaxa 1432 (1), pp. 35-56 : 52

Natterophthalmus andersoni Dronen & Penner, 1975

(syn. Philophthalmus andersoni Dronen & Penner, 1975 )

Locality: Bryan Utility Lake , Bryan, Brazos County, Texas, U.S.A., 30° 24’ N latitude, 96° 13’ W longitude .

Site of infection: Conjunctival sac of eye.

Deposited specimens: Voucher specimens (1 specimen) HWML 48502 .

Prevalence: 1of 4 birds, 25%.

Mean intensity: 3 individuals/infected bird.

Basic comparative description: Based on 3 adult specimens. Body oval, lightly spinose, 3,425 (3,360 – 3,620) long by 1,025 (910–1,145) wide. Mouth subterminal; oral sucker 200 (190–205) by 305 (280–325); prepharynx short; pharynx large, 265 (220–285) by 260 (255–297); esophagus 170 (155–195); ceca extending posteriorly to level of posterior testis. Acetabulum large, 585 (440–695) by 530 (440–585). Testes tandem, anterior testis 329 (290–400) by 530 (490–595); posterior testis 335 (295–355) by 456 (330–490). Genital pore immediately postpharyngeal, near midline of body; cirrus sac overreaching acetabulum posteriorly, extending some distance into hindbody. Ovary oval to round, immediately pretesticular, 195 (160–280) by 220 (190–260). Vitellaria generally large, follicular, occaisionally fine, granular in larger specimens. Eggs nonoperculate, 76 (72–78) long.

Remarks. Dronen & Penner (1975) reported N. andersoni (as Philophthalmus andersoni ) from the ocular orbit of royal terns collected from California and Florida (see Table 1). It should be noted that we have tentatively accepted the placement of both N. (P). andersoni and N. (P). hegeneri in Natterophthmus Radev, Kanev, Nollen & Sattmann, 1996 as suggested by Radev et al. (1996), based on the presence of a prebifurcal genital pore (immediately below the pharynx in N. [P]. andersoni ); however, there are a number of other characteristics used by Radev et al. (1996) to distinguish Natterophthalmus from Philophthalmus Looss, 1899 that appear to be variable among species in the 2 genera. For example, one of the primary characteristics in their key to separate these 2 genera is that species of Philophthalmus are described as having a long cirrus sac that extends posteriorly beyond the posterior margin of the acetabulum, whereas species of Natterophthalmus are considered to have a short cirrus sac that does not extend posteriorly beyond the acetabulum. Natterophthalmus andersoni and N. larsoni Penner & Trimble, 1970 appear to be exceptions because they have a cirrus sac that extends well beyond the acetabulum into the hindbody. Based on experimental infections of chicks with N. andersoni , the distance that the cirrus sac extends into the hindbody in this species is positively correlated with age up to a point where the size of the cirrus sac will then start to decline with age. Also, Dronen & Penner (1975) noted that the vitelline follicles (also used as a distinguishing characteristic in the key by Kanev et al. [2005]) in older specimens of N. andersoni became less distinct and more tubular in appearance. Penner & Trimble (1970) noted that the vitelline follicles in some of their specimens of N. larsoni (a species where the vitellaria are usually follicular) were tubular. In terms of the generic diagnoses of Radev e t al. (1996), there are several characteristics that are listed for Philophthalmus that are also found in at least some species of Natterophthalmus: The acetabula of N. andersoni , N. hegeneri , and N. larsoni are preequatorial, not equatorial (this is especially evident in older specimens); the uterine coils of N. andersoni , N. hegeneri , and N. larsoni extensively overreach the ceca laterally; and the miracidia within the eggs of both N. andersoni and N. hegeneri have well developed germinal masses within them, and in the case of N. andersoni , the germinal mass will often have a pharynx present suggesting a more advanced redial stage development.