Podocotyle Dujardin 1845

Podocotyle sp. 2

(Fig. 3)

Synonyms: Podocotyle (Podocotyle) sp. n. #2 of Armstrong (1974), Bray (1995) & Blend (1996).

Host: Western Atlantic grenadier, Nezumia atlantica (Parr) (= Ventrifossa atlantica Parr) (Gadiformes: Macrouridae: Macrourinae).

Locality: Northeastern Gulf of Mexico off Florida, 28°22’ N, 86°31’ W, depth = 710 m, 26/June/1971.

Site of infection: Intestine.

Prevalence: 1 of 21 (4.8%).

Intensity: only 1 worm.

Mean intensity: 1/1 = 1.00.

Relative density/abundance: 1/21 = 0.05.

Deposited Specimen: NHMUK 2019.4.12.23 (1 slide).

Records: 1. Armstrong (1974); 2. Bray (1995); 3. Blend (1996); 4. Present study.

Descriptions: 1, 4.

Description: [Based on 1 specimen wherein stain appears slightly faded and a tiny tear is present in posterodextral region of worm. Measurements and proportions given in Table 2.] With characteristics of genus. Body ovalelongate, rounded to slightly pointed extremities, flattened dorsoventrally, margins parallel and widest in middle 1/3 of body. Forebody slightly attenuated to rounded extremity, 1/4 body length. Hindbody wider than forebody, with parallel margins until posterior 1/4 of body where it attenuates to a more pointed extremity. Tegument smooth. Pre-oral lobe not observed. Oral sucker subspherical, subterminal, unspecialized. Ventral sucker prominent, unspecialized with wide muscular perimeter, somewhat protuberant, transversely oval and wider than long, at junction of first and second 1/4 of body. Prepharynx not observed. Pharynx muscular, round, large. Esophagus contracted, thick-walled and sinuous. Intestinal bifurcation ventrally overlapped by anterior margin of ventral sucker. Ceca conspicuous, thin-walled, voluminous, with near consistent width throughout until posterior end where ceca narrow and terminate blindly at posterior extremity; left cecum more narrowed at posterior end than right cecum.

Testes 2, median, tandem, contiguous, transversely oval to globular, intercecal, post-equatorial near junction of middle and posterior 1/3 of body. Post-testicular region occupies posterior 1/4 of body. Cirrus pouch clavate with indistinct wall, extends posterodextrally over right side of ventral sucker to level of posterior edge of sucker. Seminal vesicle internal, bi-partite; proximal portion saccate, occupies posterodextral portion of cirrus pouch; distal portion tubular and narrows towards anterior end of pouch. Pars prostatica inconspicuous; ejaculatory duct long; prostatic gland cells distributed throughout cirrus pouch with dense numbers along left margin of pouch. Genital pore submedian (sinistral), ventrally overlapped by puckered anterior margin of ventral sucker, at level of lower esophagus, midway between left margin and midline of worm. Genital atrium present.

Ovary 3-lobed, lobes inconspicuous, sub-triangular in shape, median, equatorial in middle 1/3 of body, postacetabular, contiguous to and immediately anterior to anterior testis, intercecal. Vitelline reservoir conspicuous, median to just submedian (sinistral), sub-triangular, contiguous with anterodorsal edge of ovary. Transverse vitelline ducts run dorsal to and parallel along anterior margin of ovary, extend laterally to medial walls of ceca. Canalicular seminal receptacle oval, pre-ovarian, dextral to vitelline reservoir and along midline of worm, 74 long × 44 wide. Laurer’s canal runs between ovary and vitelline reservoir, opens dorsally. Oviduct arises from anterior-most lobe of ovary (large ova seen in anterior lobe), receives both Laurer’s canal and main vitelline duct, then enters oötype anterior to ovary; large Mehlis’ gland cells present. Uterus inconspicuous, narrow, intercecal, extends posteriorly to mid-level of ovary and runs anterodorsally over ventral sucker and parallel to and along left side of distal portion of cirrus pouch before it enters genital atrium. Metraterm not observed. Vitelline fields follicular, large, circular to more elongate in shape, extend longitudinally in uninterrupted lateral bands (small gap to right of ventral sucker near body margin) from near posterior extremity anteriorly to level of anterior margin of ventral sucker (right band extends to anterior margin of sucker; left band extends anteriorly only to posterior margin of sucker); dorsal follicles along medial and lateral margins of ceca only, ventral follicles confluent over ceca, overlap lateral margins of testes, not confluent in but encroach into pre-ovarian region, in space between ovary and anterior testis, and in inter-testicular region; follicles in post-testicular region are not confluent dorsally but confluent ventrally in anteriormost area of this region. Eggs few (only 3 observed), collapsed and/or crenulated, large, operculate, amber, non-embryonated, non-filamented with nib on one pole.

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1 This specimen of P. pearsei (= “ Podocotyle species nova” of Blend 1996, p. 137–141, Fig. 16) showed evidence of contraction, forebody extension, and it was collected from a different locality than the other voucher materials (NE Gulf of Mexico off Florida vs Western Gulf of Mexico off Mexico); therefore, it was kept separate in this table.

2 Of the 70 specimens of P. pearsei we collected from B. melanobranchus housed at the BRTC, these 11 specimens appeared in good condition (they showed no or very little contraction) and, thus, were selected as measureable / comparative voucher material.

3 AT, anterior testis; L, length; PT, posterior testis; VS, ventral sucker; W, width; ranges followed by mean in parentheses where applicable; number [n] of measurements provided if different from total number of worms examined.

4 Proportion of body length.

5 Bloated / inflated eggs of Podocotyle sp. 1 were 54–56 (54.4) [n = 5] long × 26–32 (28.8) [n = 5] wide; Nib on pole of egg 4–6 (4.8) [n = 5] long.

6 Nib on pole of egg of Podocotyle sp. 2 measures 4–6 (5.3) [n = 3] long.

Excretory bladder I-shaped/tubular, wide, very conspicuous, extends to posterior border of posterior testis. Excretory pore terminal.