Polystomoides nelsoni, Du Preez, Louis H. & Van Rooyen, Michelle, 2015

Du Preez, Louis H. & Van Rooyen, Michelle, 2015, A new polystomatid (Monogenea, Polystomatidae) from the mouth of the North American freshwater turtle Pseudemysnelsoni, ZooKeys 539, pp. 1-9 : 4-5

Taxon classification Animalia Polystomatidea Polystomatidae

Polystomoides nelsoni sp. n. Figs 1, 2

Specimens studied.

Morphological description based on ten sexually mature worms. Holotype (NMB 380) nine paratypes (NMB 381-389) deposited in the Parasitic Worm Collection, National Museum, Aliwal Street, Bloemfontein, South Africa.

Type host.

Pseudemys nelsoni (Carr, 1938) sexually mature male.

Type locality.

United States Geological Survey USGS-BRD facility, 7920 N.W. 71st St., Gainesville, Florida, USA (29°43'31"N, 82°25'04"W).

Etymology.

The species is named after the host.

Site.

Mouth.

Description.

Based on ten egg-producing adults. The average measurement is given, followed by the range given in parentheses. Measurements are given in micrometres (µm). Larval (oncomiracidia) measurements are given for the marginal hooklets.

Adult: General characteristics given of mature, egg-producing parasite (Figure 1). Body elongated and ellipsoid, total length 5.707 (3.052-7.378), greatest width 2.278 (1.276-2.751), width at vagina 2.270 (1.276-2.739), haptor length 1.310 (912-1.616), haptor width 1.931 (1.232-2.182); haptor length to body length ratio 0.23; six haptoral suckers, mean diameter 564 (148-781), haptors internally supported by an elaborate skeletal structure. Two pairs of hamuli: inner pair 69 (48-95) long with a hamulus hook length of 21 (17-26); outer pair 138 (104-173) long with a hamulus hook length of 22 (19-26). Mouth sub-terminal. False oral sucker 788 (398-1 036) wide; pharynx length 539 (345-917), width 658 (391-881). Intestine bifurcates with no diverticula and no anastomoses present; caeca extend to the end of the body proper and do not join posteriorly nor do they extend into the haptor. Testis compact, mid-ventral, medial, and posterior to ovary (Figure 1); 401 (108-687) long and 564 (148-781) wide. Genital atrium median, ventral, posterior to intestinal bifurcation: 586 (302-816) in length with 123 (108-132) spines, 101 (93-106) long. Ovary, dextral, anterior, 38% of body length; ovary length 251 (102-330), and width 86 (27-124). Short tubular uterus anterior to ovary, containing up to eight eggs; length 227 (182-274), and width 144 (118-194). No intra-uterine development, operculated egg. Vitellarium extends throughout most of the body proper posterior to the pharynx except the central area around the gonads (Figure 1). Oncomiracidia. Marginal hooklets were observed and measured on slides prepared from incubated oncomiracidia (Figure 2). Marginal hooklet I found to be 28 (25-30) and hooklets II - VIII 27 (25-29).

Remarks.

Polystomoides nelsoni sp. n. differs from other Polystomoides species by a combination of characters. With a body length of 5.707 (3.052-7.378), Polystomoides nelsoni sp. n. is longer than Polystomoides megaovum (2.910), Polystomoides asiaticus (4.600), Polystomoides siebenrockiella (3.580) and Polystomoides uruguayensis (2.560-2.650). However, Polystomoides nelsoni sp. n. has a shorter body length when compared to Polystomoides australiensis (6.193), Polystomoides fuquesi (7.480-7.550), Polystomoides godavarii (4.200-8.030) and Polystomoides ludhianae (6.640-10.060). In terms of the length and width of the haptor, Polystomoides nelsoni sp. n. (1.310 × 1.931) differs from Polystomoides megaovum (620 × 880), Polystomoides asiaticus (1.100 × 1.700), Polystomoides siebenrockiella (780 × 1.060), Polystomoides australiensis (1.353 × 2.190) and Polystomoides godavarii (1.120-1.620 × 1.250-1.710).