Centrorhynchus guira n. sp, 2010

Lunaschi, L. I. & Drago, F. B., 2010, A new species of Centrorhynchus (Acanthocephala, Centrorhynchidae) endoparasite of Guira guira (Aves, Cuculidae) from Argentina, Helminthologia 47 (1), pp. 38-47 : 38-46

Centrorhynchus guira n. sp .

( Figs. 1 – 2 )

Description: Based on 10 mature specimens (5 males and 5 females). Body elongated, filiform, with sexual dimor-phism, females longer than males. Posterior end of females dilated and rounded. Proboscis nearly cylindrical, divided into 2 portions by constriction at level of insertion of the proboscis receptacle; anterior portion of proboscis almost cylindrical, slightly swollen at level of last true hooks; posterior portion conical. Neck short. Trunk cylindrical, with evident swelling in anterior region and internal pseudosegmentation. Proboscis receptacle with double wall. Cerebral ganglion oval, situated approximately in the middle of the proboscis receptacle. Lemnisci digitiform, longer than proboscis receptacle. Proboscis armament consists of 32 longitudinal rows; 29 longitudinal rows with 18 hooks per row and 3 longitudinal rows with 19 hooks per row. First 8 – 9 true hooks, longer, with posteriorly directed roots, swollen at base; in alternating rows, the last true hooks are smaller; next 4 hooks transitional with roots directed anteriorly (the first with 4 lateral alate processes and the last with slender root swollen at base); remaining 6 hooks on posterior portion of proboscis, spiniform. Pattern of hooks per row: 8 – 9 + 4 + 6.

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Male. Body 26.9 – 31.9 (28.8) in total length. Proboscis 0.79 – 0.97 (0.86) long; anterior portion elongated 0.53 – 0.68 (0.59) long, 0.28 – 0.38 (0.31) wide; posterior portion 0.20 – 0.34 (0.27) long, 0.34 – 0.52 (0.40) wide. First 7 true hooks: blade 38 – 48 (41) µm long, root 45 – 60 (49) µm long; last true hook: blade 24 – 31 (27) µm long, root 21 – 36 (29) µm long; transitional hooks: blade 19 – 33 (26) µm long, root 17 – 21 (20) µm long; spiniform hooks: 14 – 26 (21) µm long. Neck 30 – 68 (47) µm long, 411 – 513 (460) µm wide. Trunk 26.1 – 30.9 (27.9) long; anterior trunk widened 4.4 – 5.4 long, 1.02 – 1.28 wide, separated from remainder trunk by a constriction. Proboscis receptacle, 1.4 – 1.6 (1.5) long, 0.34 – 0.48 (0.41) wide. Lemnisci 1.94 – 2.34 (2.14) long, 0.31 – 0.43 (0.39) wide. Testes oval, located in tandem, contiguous or slightly overlapping one another in anterior part of trunk; anterior testis 1.06 – 1.20 (1.14) long, 0.54 – 0.63 (0.59) wide, situated at 0.94 – 1.54 (1.22) from proboscis receptacle; posterior testis 1.1 – 1.29 (1.20) long, 0.51 – 0.66 (0.60) wide. Cement glands 3, tubular, situated immediately posterior to hind testis. Säfftigen's pouch conspicuous, 2.71 – 2.97 (2.88) long, 0.54 – 0.87 (0.75) wide. Genital pore terminal. Copulatory bursa, rounded or cylindrical when fully everted, 2.09 – 2.14 (2.11) long, 1.23 – 2.03 (1.63) wide.

Female. Body 38.8 – 50.4 (43.6) in total length. Proboscis 0.92 – 1.0 (0.95) long; anterior portion 0.48 – 0.69 (0.60) long, 0.34 – 0.48 (0.39) wide; posterior portion 0.31 – 0.43 (0.35) long, 0.44 – 0.49 (0.47) wide. First 7 true hooks: 40 – 48 (43) µm long, root 36 – 64 (49) µm long; last true hook: blade 31 – 36 (34) µm long, root 36 – 45 (40) µm long; transitional hooks: blade 21 – 29 (26) µm long, root 14 – 26 (19) µm long; spiniform hooks: 17 – 28 (22) µm long. Neck 39 – 68 (54) µm long, 478 – 522 (506) µm wide. Trunk 37.8 – 49.4 (42.6) long; anterior trunk widened 5.57 – 5.88 (5.70) long; 1.10 – 1.43 (1.26) wide, separated from remainder trunk by a constriction. Proboscis receptacle 1.69 – 1.77 (1.73) long, 0.37 – 0.46 (0.42) wide. Lemnisci 1.8 – 2.71 (2.43) long, 0.24 – 0.39 (0.29) wide. Female genital tract (measured from opening of uterine bell to genital pore in one dissected specimen) 2.63 in length from opening of uterine bell to genital pore; uterine bell 0.34 long, 0.25 wide; uterus 1.7; vagina 0.34 long, provided with 2 sphincters. Genital pore ventral, subterminal, at 0.29 – 0.53 (0.44) from tip posterior end. Eggs elongated, without polar prolongations and with outer shell corrugated, 53 – 63 x 24 – 29 (57 x 27) µm.

Type host: Guira guira (Gmelin) (guira cuckoo) ( Cuculiformes : Cuculidae )

Site of infection: intestine.

Type locality: La Marcela farm (26°17’35”S; 59°06’67”W), Pirané, Formosa Province, Argentina.

Specimens deposited: MLP Nº 5945 (holotype male); Nº 5946 (allotype female) ; Nº 5947 – 5950 (paratypes)

Etymology: The new species is named after the specific name of the host.

Remarks

According to Golvan (1956), in the species of the genus Centrorhynchus the number of longitudinal rows, number of hooks per row, size of the blades and morphology and size of roots are the characteristics with greater taxonomic value. Golvan (1960) described three types of hooks in this genus: true, spiniform and transitional. These last hooks are characterized by having roots directed anteriorly and lateral alate processes, and can be absent in some species. The presence of transitional hooks readily distinguishes the specimens obtained from G. guira from most of the Neotropical species of Centrorhynchus . At present, five species have been reported with transitional hooks: Centrorhynchus polymorphus Travassos 1925 , Centrorhynchus albidus Meyer 1932 , Centrorhynchus microcephalus ( Bravo Hollis 1947) Golvan 1956 , Centrorhynchus kuntzi Schmidt & Neiland 1966 , Centrorhynchus crotophagicola Schmidt & Neiland 1966 . Among these species, C. kuntzi is the most similar species to C. guira n. sp ., by having transitional hooks with lateral alate processes as describe Golvan (1960), and the first of them with 4 alate processes. However, this species differs mainly in the number of hooks per row (22 – 27 versus 18 – 19) and spiniform hooks (14 – 18 versus 6), and by possessing a digitiform papilla at posterior end ( Schmidt & Neiland, 1966; Nickol, 1983). In addition, the measurements of body, testes, Säfftigen's pouch and eggs are smaller than C. guira n. sp. ( Table 2 , 3 ).

The remaining species differ mainly from the new species in having transitional hooks without lateral alate processes. The proboscis armature of C. albidus differs from that observed in the new species by having a lesser number of longitudinal rows (28 – 30), a greater number of hooks per row (20 – 22), and a different pattern of hooks per row (8 + 4 + 10) ( Schmidt & Neiland, 1966; Fig. 5). The females differ by having smaller body and eggs, whereas the males differ in the size of body and testes ( Table 2 , 3 ). The proboscis armature of C. crotophagicola is similar to C. guira n. sp. in the number of longitudinal rows of hooks. (32 – 35). Schmidt and Neiland (1966) characterized this species by the presence of 15 – 17 hooks per rows, of which the first 8 – 9 in each row have well-developed roots, being the remaining hooks rootless but with strong anteriorly directed manubrium, without detailing the presence of transitional hooks. Later, Dimitrova and Gibson (2005) described encysted juveniles of this species from Anolis lineatopus lineatopus Grey and A. sagrei Duméril &Bibron from Jamaica and reported new data for the pattern of hooks per row: 8 – 9 + 3 + 4-5 (exceptionally 6). The most important morphological differences between the proboscis armature of the new species and C. crotophagicola , are the greater number of hooks per longitudinal row (18 versus 15 – 17) and the greater number of transitional hooks (4 versus 3). Moreover, the females differ by having a terminal papilla at posterior end, smaller proboscis, proboscis receptacle and eggs than C. guira n. sp. ( Table 2 , 3 ).

The armature proboscis of C. microcephalus differs mainly from that observed in C. guira by having a greater number of longitudinal rows (36 – 38) and the following pattern of hooks: 9 + 3 + 5 (see Bravo Hollis, 1947; Fig. 2 ). The males differ by having smaller body, lemnisci and proboscis, whereas the females differ by having a smaller proboscis, proboscis receptacle and lemnisci ( Table 2 , 3 ). Finally, C. polymorphus differs from the new species in the pattern of hooks per row (7 + 3 + 7), by having a lesser number of longitudinal rows (30) and hooks per row (17), and by having smaller body, proboscis, proboscis receptacle, lemnisci and testes ( Table 2 , 3 ). On the other hand, the taxonomic position of this species is controverted since Golvan (1956) include it in the subgenus Longirostris , as C. (Longirostris) polymorphus ; posteriorly, Golvan (1960) and Yamaguti (1963) consider it as C. polymorphus and Dimitrova and Gibson (2005) believe that this species better fits Sphaerirostris Golvan 1956 than Centrorhynchus due to the shape and size of the body and proboscis.

Figures

Fig. 1. Microphotographs of Centrorhynchus guira n. sp. a - proboscis armament; b - detail of transitional hooks; c - female, reproductive system; d - female, posterior end; e - male, posterior end with everted copulatory bursa; f - detail of uterine bell; g - detail of uterus; h - vagina showing 2 sphincters; i - egg, superficial view; j - egg, detail of acanthor and middle shell without polar prolongations.

Fig. 2. SEM micrographs of Centrorhynchus guira n. sp.: a - proboscis armament, lateral view; b - proboscis armament, apical view, showing longitudinal rows with 19 hooks per row (arrow); c - female, posterior end; d - male, posterior end with everted copulatory bursa; e - internal anatomy showing an apparent segmentation.