Mediorhynchus ayeri, R. & Smales, 2014

Smales, L. R., 2014, Acanthocephala, including the descriptions of two new species of Mediorhynchus (Gigantorhynchidae) from birds from Paraguay, South America, Revue suisse de Zoologie 121 (2), pp. 261-276 : 272-274

Mediorhynchus ayeri sp. n.

Figs 18-24

MATERIAL EXAMINED: MHNG-INVE-84848 ; holotype male, small intestine, Pitangus sulfuratus Linneaus, 1776 ( Tyrannidae ), Paraguay, Panchito Lopez , 24.10.1982. – MHNG-INVE-84849 ; paratype (allotype) female, small intestine, Pitangus sulfuratus Linneaus, 1776, Paraguay, Panchito Lopez, 24.10.1982. – MHNG-INVE-38446 ; 1 cystacanth, 1 male, 4 females, paratypes, small intestine, Pitangus sulfuratus Linneaus, 1776, Paraguay, Panchito Lopez , 24.10.1982. – MHNG-INVE-38421 ; 2 females, voucher specimens, small intestine, Agelaioides badius (Vieillot, 1819) (Icteridae) , Paraguay, Pozo Arias , 12.08.1996. – MHNG-INVE-38404 ; 2 females, voucher specimens, small intestine, Zonotrichia capensis (Statius Mueller, 1776) (Emberezidae), Paraguay, General Diaz , 2W, 19.10.1989. – MHNG-INVE-38445 ; 3 males, voucher specimens, small intestine, Arremon flavirostris Swainson, 1830 (Emberezidae), Paraguay, Pilar , 19.10.1982. – MHNG-INVE-38442 ; 2 males, voucher specimens, small intestine, Furnarius rufus (Gmelin, 1788) (Furnariidae), Paraguay, Tobati , 20.03.1985. – MHNG- INVE-38390 ; 2 males, 2 pieces worm, small intestine, Furnarius cristatus Burmeister (Furnaridae), 1888, Paraguay, Transchaco 293, 03.11.1988.

ETYMOLOGY: This species is named in honour of Jacques Ayer, the director of the Natural History Museum, Geneva.

DESCRIPTION

General: (based on 9 males and 4 females) Relatively small robust worms, trunk more of less cylindrical, body wall thick, aspinose (Figs 18, 22). Main lacunar canals with regular lateral branches. Proboscis conical, truncated, in 2 parts; anterior proboscis with rooted hooks, posterior proboscis wider with spines (Fig. 20); Roots of hooks flask shaped with rounded larger posterior ends with scalloped edges, anterior spines with much reduced flask shaped roots, posterior spines with basal discs (Fig. 19). Proboscis armature similar in both sexes, 18-22 rows of 4-5 hooks, about same number of irregular rows 2-3, usually 2 spines; male, longest hooks 20, 21, 22, shortest hooks 15, 15, 19; spines 5, 10 long. Neck unarmed, conical, widest at junction with broader trunk. Proboscis receptacle attached anteriorly at junction between anterior and posterior proboscis, with cerebral ganglion near mid region (Fig. 24). Lemnisci long, slender, equal, inserted at base of neck, extend beyond anterior testis in male (Fig. 18). Genital pore, male and female, terminal.

Male: (Based on 9 specimens) Trunk 4-7 (4.9) mm long 440-970 (650) wide. Proboscis 265-535 (424) long, 230-605 (347) wide; anterior proboscis 160-385 (247), posterior proboscis 95-150 (129). Neck 20-200 (126) long, 230-770 (443) wide. Proboscis receptacle 350-680 (504) long, 135-235 (187) wide. Lemnisci 1535-3145 (2150) long, 80-150 (112.9) wide. Testes ovoid, tandem, usually contiguous, in mid third of trunk; anterior testis 850-1190 (1059) long, 180-610 (322) wide; posterior testis 765-1375 (1080) long, 180-680 (368) wide. Cement glands 8 globular, in cluster, 175-460 (279) in diameter. Saefftigen’s pouch 375-690 (500) long (Fig. 23).

Female: (based on 4 specimens, none with proboscis fully extended) Trunk 15-22 (18.5) mm long, 765-1020 (850) wide. Proboscis 360-535 (448) wide; lengths of anterior and posterior proboscis not determined. Neck 85-135 (110) long, 435-440 (438) wide. Proboscis receptacle 500-800 (650) long, 265-295 (285) wide. Lemnisci 2940-3095 (3018) long, 150 wide. Reproductive tract, 300-650 (484) long, about 20-29.5% of trunk length (Fig. 21). Eggs not seen.

Cystacanth: (single specimen) proboscis 330 long, 247.5 wide; anterior proboscis 220, posterior proboscis 110 long.

COMMENTS: Mediorhynchus ayeri sp. n. demonstrates the characters of the genus as described by Van Cleave (1916) and discussed by Schmidt & Kuntz (1977) and Amin & Dailey (1998). Consideration of the key of Schmidt & Kuntz (1977) indicated that M. ayeri with a proboscis armature of 18-22 rows of 4-5 hooks, was closest to M. gallinarum (Bhalerao, 1937) which also has a proboscis armature of 18-22 rows of 4-5 hooks. The proboscis armature of M. ayeri , however, differs from that of M. gallinarum in the number of rows of spines (about 22-24 compared with 25-30 rows) the number of spines in each row (2-3, usually 2, compared with 2-6) and the size of the hooks (largest hooks 20-22 compared with 40-70). Moreover M. ayeri , a smaller worm (males 4-7mm), is found in passerines from South America whereas M. gallinarum , a larger worm (males 9-26), is found in galliforms across India and Southeast Asia ( Amin et al., 2013). Neither the species listed or described by Amin et al. (2008) nor the species described since 2008, as listed above, have proboscis armature similar to that of M. ayeri .

Of the species previously known from South America M. ayeri comes closest to M. emberizae , which has a proboscis armature of 20-22 rows of 5-6 hooks and 2-3, usually 3 spines as compared with 18-22 rows of 4-5 hooks and 2-3, usually 2 spines ( Petrochenko, 1958). Mediorhynchus ayeri further differs from M. emberizae in having smaller hooks (largest hooks 20-22 compared with 30-35), smaller testes (765-1377 compared with 1020-2210) shorter lemnisci in the female (2940-3095 compared with 3700-9350) and a shorter female reproductive tract (300-650 compared with 805- 1055).