Centrorhynchus mariauxi, R. & Smales, 2011

Smales, Lesley R., 2011, Centrorhynchidae (Acanthocephala) including the description of new species of Centrorhynchus from birds from the Côte d’Ivoire, Africa., Revue suisse de Zoologie 118 (2), pp. 307-318 : 311-314

Centrorhynchus mariauxi sp. n.

Figs 5-13

MATERIAL EXAMINED: Holotype male, paratypes, 8 pieces males, 2 females without proboscis, 4 pieces females from Kaupifalco m. monogrammicus (Temminck, 1824) small intestine; Côte d’Ivoire, Lamto, 9.02.1987, J. Mariaux ( MNHG INVE 38486 , INVE 69971 ). Prevalence: 50%.

DESCRIPTION

General: Trunk, spineless, elongate, cylindrical, female dilated posteriorly from about 500 to about 1500 above posterior end. Proboscis in 2 parts with constriction at insertion of proboscis receptacle, about 45% of distance from apex to proboscis base; anterior proboscis sub spherical. Proboscis armed with 34-36 rows 15-19 hooks. Anterior 2-3 hooks with large simple roots, thorns 20-25.5 (male) long; next 4-5 hooks transitional, having short roots with luniform- cresentic manubria, thorns 25.5- 44 (male) long; 9-11 spiniform hooks inserted on posterior part of proboscis posterior to constriction, thorns 20-40 (male) long. Neck spineless, well defined, shorter than broad. Proboscis receptacle double walled. Lemnisci tubular, inserted at base of neck, extend posteriorly beyond proboscis receptacle. Cerebral ganglion located at mid region of proboscis receptacle, just posterior to neck. Principal canals of lacunar system lateral, connected by transverse anastomoses.

Male: based on one intact specimen. Trunk 25 mm long, 1200 at widest part. Proboscis total length 605, greatest width 368; posterior part 335 long 315 wide. Neck 300 long, 400 wide. Proboscis receptacle 1360 long, 235 wide; lemnisci 1273 long. Testes oval, tandem, not contiguous 1.1mm apart; anterior testis, 3.00 mm from anterior end of trunk, 529 long, 268 wide; posterior testis 556 long, 275 wide. Cement glands, 3, elongate, tubular, begin immediately posterior to end of posterior testis, 17.5 mm long; cement ducts elongated, 1800 long; Saefftigen’s pouch 1250 long; entire male system occupying about 88% trunk length.

Female: based on anterior end one specimen, posterior end one specimen and longest piece. Trunk longer than 70mm, main trunk 500-600 wide, dilated posterior part 700-900 wide. Proboscis total length, 780 greatest width 390, posterior part 420 long 350 wide. Proboscis receptacle 1400-2200 long, 290-400 wide; lemnisci 1615 long. Genital apparatus, uterine bell to genital pore, 2000 long. Genital pore sub terminal. Eggs oval, external shell smooth, thick, 45 long, 22 wide.

COMMENTS: Centrorhynchus mariauxi n. sp. conforms to the diagnosis of the genus given by Golvan (1956, 1960). In his examination of the morphological characters available in the family for systematic analysis those of the proboscis armature, the number of longitudinal rows of hooks, the number of hooks in each row and the dimensions of the thorns and roots of the hooks were the most useful. Further he determined that the number of hooks per row was the most stable of these characters ( Golvan 1956). Accordingly he subdivided the genus Centrorhynchus into 3 groups; those species with less than 30 longitudinal rows of hooks, those with 30-40 rows and those with more than 40 rows of hooks. With a proboscis armature of more than 30 rows C. mariauxi falls into Group 2 ( Golvan 1956). The hook formula of 34-36 longitudinal rows of 15-19 hooks comprising 6-8 hooks with roots and 9-11 spiniform hooks distinguishes it from all other species in that group. Since then about 50 valid species of Centrorhynchus have been added to the genus including 20 species that have between 30 and 40 longitudinal rows of hooks.

Species known to occur in continental Africa that have a proboscis armature of 30-40 rows of hooks include C. chabaudi , from the Sudan and now the Côte d’Ivoire, C. gendrei from the Republic of Guinea, C. milvus from Egypt and Senegal, C. clitorideus (Meyer, 1931) from Egypt, C. globocaudatus from Egypt and West Africa, C. polemati Troncy, 1970 from Chad and C. undulatus Dollfus, 1951 from Morocco. Of these only C. chabaudi with 17-24, C. milvus with 18-21 and C. undulatus with 21 have a similar number of hooks per row. C. chabaudi can be distinguished by having 5-6 anterior hooks with longer thorns, 55-96 compared with 20-25 for C. mariauxi and small triangular roots on the anterior-most rows of spiniform hooks. The lemnisci of C. mariauxi are shorter and the testes smaller, further apart and more posterior than those of C. chabaudi (see Golvan, 1957 and this study). C. milvus differs from C. mariauxi in the hook pattern and proboscis length; 8-9 hooks with large roots, 5-6 transitional hooks and 5-6 spines on a longer proboscis, 0.8-1.19mm, compared with 2-3 large, 4-5 transitional and 9-11 spiniform hooks on a shorter proboscis, 0.61-0.77 ( Ward, 1956; Dimitrova & Gibson 2005). The description of C. undulatus (females only) is brief. The only measurements are of the trunk, 15-18 mm, much shorter than for female C. mariauxi which are longer than 70 mm. Comparison of text and figures for C. undulatus suggests that the proboscis was about 1mm long with an armature of 21 hooks per row comprising 6 with large simple roots, thorns about 35-45 long, 3 transitional forms and 12 spiniform hooks ( Dollfus, 1951). These differences seem sufficient to distinguish the two species. Comparative measurements for the west African species are given in table 2.

There are 12 known extra- limital species with 30-40 longitudinal rows of hooks: namely C. bethaniae George & Nadakal, 1987 , C. brygooi Golvan, 1965 , C. conspectus Van Cleave & Pratt, 1940 , C. crotophagicola Schmidt & Neiland, 1966 , C. fukiensis, Wang 1966 , C. guira Lunaschi & Drago, 2010 , C. hagiangensis Petrochenko & Phan, 1969 , C. kuntzi Schmidt & Neiland, 1966 , C. madagascarensis ( Golvan, 1957) , C. nicaraguaensis Schmidt & Neiland, 1966 , Centrorhynchus cf p olymorphus Travassos, 1926, C. undulatus (Nitzsch in Giebel, 1886) (see Dollfus 1951; Golvan 1957, 1965, 1994; Hartwich 1956; Schmidt & Neiland 1966; Wang 1966, George & Nadakal 1987; Richardson & Nickol 1995; Dimitrova et al. 1997; Dimitrova & Gibson 2005; Lunaschi & Drago, 2010). None of the species listed, however, has a similar hook pattern to that of C. mariauxi with as few as 2-3 true hooks in each row.

The most similar extra-limital species is C. conspectus Van Cleave & Pratt, 1940 which has 28-38 rows of 16 -19 hooks of which 4-5 have long simple roots and 12-15 are spiniform, but differs from C. mariauxi in having no transitional hooks ( Richardson & Nickol 1995). Other species with a similar total number of proboscis hooks differ in numbers and sizes of each hook form. For example C. nicaraguensis has 39 rows of 17 hooks but no transitional hooks; and C. crotophagicola has 32-35 rows of 15-17 hooks, but differs in having 8-9 hooks with long simple roots and 7-9 hooks with manubria ( Schmidt & Neiland, 1966).

C. acanthotrias (Linstow, 1883) was assigned to C. buteonis by Meyer (1932, see Yamaguti 1963), listed as Echinorhynchus s. l. by Petrochenko (1985) and under genera incertae sedis by Yamaguti (1963) and Amin (1985). Never the less the species was noted by Petrochenko (1958) as ‘obvious that it belongs to the Centrorhynchinae or even Centrorhynchus ’ and listed as a valid species by Golvan (1994). However the description is incomplete. Having 33-40 longitudinal rows of hooks the most anterior ones with straight roots, the median ones with bifurcated roots and the posterior ones with simple roots (Petrochenko 1958) C. acanthotrias may also be similar to C. mariauxi .