Pseudocryptotropa surniculi Tkach, Chermak & Greiman, 2023

Tkach, Vasyl V., Chermak, Taylor P., Patitucci, Kaylyn K., Greiman, Stephen E., Binh, Tran Thi & Olson, Peter D., 2023, Jumping continents and major host lineages: phylogeny and diversity of the enigmatic Cryptotropidae (Platyhelminthes: Digenea), Zoological Journal of the Linnean Society 199 (2), pp. 533-552 : 541-545

Pseudocryptotropa surniculi Tkach, Chermak & Greiman sp. nov.

( Figs 3B, C , 5B , 6A, B , 7 )

Type host: Surniculus velutinus Sharpe ( Aves: Cuculidae ).

Site in host: Small intestine.

Type locality: Occidental Mindoro Province, Mindoro Island, Philippines.

Type material: The type series consists of 21 mature specimens deposited in the HWML. Holotype (marked on a slide containing five specimens): HWML 216832, labelled ex. Surniculus velutinus, small intestine, Occidental Mindoro Province, Mindoro Island, Mindoro Island, Philippines, 14 July 2013, coll. S. Greiman. Paratypes: HWML 216833 (lot of seven slides), labels identical to the holotype.

GenBank sequences: Oº534011 (ribosomal), Oº469316 (cox1).

ZooBank registration: urn:lsid:zoobank.org:act:769586D7-2EAA-4FF0-A1BA-A30FB4D2E716 .

Etymology: The species is named asser the genus of the definitive host from which it was collected.

Description (based on 21 adult specimens; measurements of holotype given in text; measurements of entire series given in Table 5 ): Body 532 long, broad, flaưened, with rounded anterior end and either blunt or somewhat concave posterior end; body width at level of ventral sucker 399. Body length-to-width ratio 1.3. Forebody 248. Tegument armed with minute spines densely covering entire body with exception of small areas around excretory pore and genital atrium. Shape of spines varies slightly in different regions of body ( Fig. 7 ). Oral sucker subterminal, rounded, 77 × 90. Ventral sucker round, 71 × 71. Oral sucker width-to-ventral sucker width ratio 1.3. Prepharynx indistinct; pharynx rounded, 45 × 34. Oesophagus 33, shorter than pharynx length. Caecal bifurcation midway between suckers; caeca short, terminating approximately at level of centre of ventral sucker and anterior margin of testes.

Two testes, opposite, longitudinally elongated, weakly lobed, immediately postacetabular, reaching anterior level of mid-section of ventral sucker. Right testis 204 × 135, less testis 191 × 133. Copulatory pouch long, 211 × 45, antero-sinistral to ventral sucker, transversally oriented. Proximal end of copulatory pouch overlaps anterior margin of ventral sucker; distal end curves towards dorsal surface in hook-like manner. Copulatory pouch contains winding seminal vesicle, prostatic gland and ejaculatory canal; evaginated cirrus not observed. Genital pore dorsal, extracaecal, near posterior end of less caecum.

Ovary 96 × 110, irregular in shape, anterior to the seminal receptacle, largely overlapping with ventral sucker, posterodextral to it. Seminal receptacle voluminous, 144 × 86, situated between testes, immediately posteriorly to ovary. Mehlis’ gland and Laurer’s canal not observed. Vitellarium extensive, in form of numerous, small, irregularly shaped follicles arranged in two transverse fields, one in anterior half of body between oral and ventral suckers and another at the posterior end of the body, immediately posterior to testes, slightly overlapping their posterior margins.

Uterus ventral to gonads, mostly in middle third of body, expanding laterally to margins of body on both sides and reaching posteriorly between testes to level of mid-length of testes. Metraterm well defined, 117. Uterus contains numerous operculate eggs, 37–41 × 18–19. Eggs possess polar filaments on each pole of egg. Polar filaments consist of several fibres aưached/ glued together ( Fig. 3B, C ). Excretory pore terminal. Excretory vesicle Y-shaped, with short stem and short arms reaching level of posterior margin of seminal receptacle.

Remarks

Pseudocryptotropa surniculi clearly belongs to the genus Pseudocryptotropa based on its morphological characteristics including, but not limited to, the dorsal genital pore, the position of gonads, copulatory pouch and uterus, as well as the general body shape. It is morphologically similar to the type species, Pseudocryptotropa macrotestis Belopolskaya, 1954 , described from the grey nightjar ( Caprimulgus jotaka Temminck & Schlegel, 1845 ) in the Far East of Russia. Khotenovsky (1965) has provided a detailed redescription of Ps. macrotestis based on type specimens; therefore, we use the redescription for our comparison. The new species differs from Ps. macrotestis by the somewhat lobed testes (smooth in Ps. macrotestis ), curved the distal end of the copulatory pouch (straight in Ps. macrotestis ), much shorter stem of the excretory vesicle, which bifurcates at the level of the posterior margin of the testes (bifurcated immediately posteriorly to the ventral sucker in Ps. macrotestis ), and much shorter arms of the excretory vesicle, which reach only the level of mid-length of the testes (reach the level of the ventral sucker in Ps. macrotestis ). Although eggs of Ps. surniculi possess polar filaments not reported in Ps. macrotestis , we do not consider this to be a unique feature among distinguishing characters because we believe that the polar filaments were probably overlooked in Ps. macrotestis .

Pseudocryptotropa surniculi is readily differentiated from Pseudocryptotropa nycticebi Rohde, 1962 by having much larger testes (see Rohde, 1962; Table 5 ), caeca reaching or almost reaching the testes (ending at a significant distance from the testes in Ps. nycticebi ), much larger seminal receptacle, much shorter oesophagus and vitelline follicle fields coalescing in the anterior third of the body (disjunct in Ps. nycticebi ).

The differentiation from the second new species of Pseudocryptotropa described in the present work is provided below.

Figures

Figure 3. Morphological details of some Cryptotropidae. A, stylet protruding from the genital atrium of Renschetrema sp. B, C, eggs released from the uterus of Pseudocryptotropa surniculi.

Figure 5. Position of copulatory pouch in the four new species described in this study. A, Cryptotropa acanthosauri. B, Pseudocryptotropa surniculi. C, Pseudocryptotropa testilobata. D, Paracryptotropa peruviana.

Figure 6. New species of Pseudocryptotropa. A, Pseudocryptotropa surniculi, ventral view of the holotype. B, P. surniculi, testes of a paratype. C, Pseudocryptotropa testilobata, ventral view of the holotype. D, P. testilobata, testes of a paratype.

Figure 7. Scanning electron micrographs of Pseudocryptotropa surniculi. A, total view, ventral. B, total view, dorsal. C, oral sucker. D, genital atrium on dorsal side of the body.E, excretory pore. F, tegumental spines on dorsal side of the anterior part of the body. G, tegumental spines on ventral side of the anterior part of the body.