Acanthocephala of Louisiana Picidae with description of a new species of Mediorhynchus.

One hundred eighty-three woodpeckers of eight species collected in Louisiana were examined for Acanthocephala. Only the red-bellied woodpecker, Centurus carolinus, was infected. One of 53 was parasitized by an irrunature specimen of Mediorhynchus grandis; three by Centrorhynchus spinosus; 12 by Mediorhynchus centurorum sp. n. The new species of Mediorhynchus is distinguished by a trunk which is very narrow in the anterior 3 mm, but is suddenly expanded farther posteriad. Proboscis armature of 22 to 24 slightly spiral rows of six hooks and four or five spines each differs from all other species of the genus except M. corcoracis and M. emberizae. The maximum number of proboscis spines in M. centurorum matches the minimum number for M. corcoracis, but usually specimens of M. corcoracis possess more spines than those of M. centurorum. M. corcoracis also has larger eggs. The new species is distinguished from M. emberizae by males with cement glands widely separated from posterior testes and lemnisci which end before reaching the level of the anterior testes. C. spinosus and M. grandis have not previously been reported from Picidae or from Louisiana. Results of a survey of Acanthocephala of Louisiana birds conducted from 1964 through 1966 were submitted to the Graduate Faculty of The Louisiana State University Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Most of the specimens used in the present study were collected during that survey. Forty-nine acanthocephalans recovered from 12 of 53 red-bellied woodpeckers, Centurus carolinus, closely resembled Mediorhynchus papillosus Van Cleave, 1916. Re-evaluation of those specimens and additional collection data have made it apparent that the worms collected from C. carolinus represent an undescribed species of Mediorhynchus. Three red-bellied woodpeckers were infected with Centrorhynchus spinosus and one with M. grandis. No mixed infections were found. Colaptes auratus (5), Dendrocopos borealis ( 4 ), D. pubescens (40), D. viUosus (4), Dryocopus pileatus (3), Melanerpes erythrocephalus (26), and Sphyrapicus varius (48) were not infected with acanthocephalans. All measurements are in microns with averages in parentheses unless otherwise stated. Numbers in parentheses following names of birds indicate number examined. Mediorhynchus cenfurorum sp. n. (Figs. 1-8) Description With characters of the genus Mediorhynchus. Body elongate and ribbonlike; males 17 to 32 mm Received for publication 22 November 1968. * Studies from the Department of Zoology, University of Nebraska, No. 402. (22) long, females 23 to 46 mm (35) long. Trunk with pronounced constriction 2 to 3.5 mm long and 350 wide slightly posterior to junction with neck. Following constricted region, trunk abruptly dilated to nearly uniform width, 1.0 to 1.8 mm (1.2), and slightly tapered at posterior extremity. No pseudosegmentation, but main lacunar canals with regular prominent lateral branches. Proboscis in shape of truncated cone, occasionally almost cylindrical; 571 to 744 (623) long, 192 to 240 (222) wide at apex, 336 to 542 (412) wide at level of proboscis receptacle insertion, and 370 to 624 (474) wide at base; armed anteriorly with 22 to 24 slightly spiral rows of 6 hooks each and posteriorly with 22 to 24 rows of 4 or 5 spines each. Largest hook roots 39 to 46 (43) long, 6 to 10 (9) wide anteriorly and expanded posteriorly to circular, trapezoidal, or elongate disc 12 to 22 (16) wide. Thorns of hooks 38 to 46 (40) long, spines 29 to 34 (31) long. Each hook and spine surrounded by a papilla. Papillae around hooks and spines vary in height and prominence. Neck 192 to 258 (208) long, with pair of lateral sensory pits about 12 behind last spines. Proboscis receptacle 0.9 to 1.3 mm long, with pyramid-shaped ganglion, about 250 long and 90 wide, in posterior half located at about the level of neck-trunk boundary. Lemnisci 6.1 to 7.9 mm (6.7) long in males, 9.7 to 12.2 mm ( 10.1) long in females; about 1.3 wide in both sexes; well separated from anterior margin of front testis. Males with 2 spindle-shaped testes about equal in size, arranged in tandem, 2.20 to 3.45 mm (2.57) long and 644 to 1,010 (791) wide. Testes widely separated from each other and from group of eight pyriform cement glands. Cement glands unequal in size 326 to 768 (398) at widest point. Entire male reproductive system usually in posterior half of trunk occupying 43% to 49% of trunk length, occasionally up to 53%. Female reproductive system from anterior edge of uterine bell to genital pore occupies 3.0 to 4.5% of trunk. Eggs 41 to 48 (46) long and 24 to 29 (27) wide when measured through body wall or removed