Gryporhynchus tetrorchis, a New Dilepidid Cestode from the Great Blue Heron

Abstract

Description: Largest strobila having a scolex, 15.8 mm long, with 240 proglottids-none of them gravid. Largest headless fragment, 22 mm long, with 195 segments-some of them partially gravid. Strobila slender, subcylindric, with moderately serrate margins. Proglottids all wider than long; the mature ones trapezoidal, about 130 1t long, 220 (A wide anteriorly and 273 u posteriorly; gravid segments similar in shape to, and scarcely larger than, mature ones. Genital primordia first discernible at about 200 ?t, in segment No. 38, and mature at 10.6 mm, in No. 218, from front end. Scolex 200-253 u long by 213-286 1 wide. Rostellum comprises a distinctly outlined somewhat hyaline, medulla (83-93 x 71-78 1) and a less well defined, apparently muscular, cortex (104-150x 75-98 >) ; armed with 20 hooks in two rows. Front hooks 60-72 u long, 30-36 from tip of handle to tip of guard, 36-41 l corresponding measurements of back hooks-35-42, 1821, 21-23, u. Neck very short. Dorsal and ventral excretory canals approximately equal in size. Relationship of genital ducts to excretory vessels not observed. Genital pores unilateral, sinistral, pre-equatorial, and small as compared with the atria. Genital atrium in a mature segment, 50 !& deep and 38 ,u in longitudinal diameter (exclusive of special pouches mentioned below); provided with 4 very prominent claw-like genital spines about 21 u& long, located 2 in each of 2 special pouches situated one in front of, and one behind, the vaginal pore. Testes, 4 in number (no variation in number observed), spheroidal, 45-68 p in diameter when mature, grouped in central portion of segment posterodorsal to female organs; still recognizable in gravid proglottids, arranged in a transverse row along posterior side. Cirrus pouch, 75 x 45 p, ellipsoidal, extends mediosubanteriad to near middle of segment, contains cirrus in distal, and a loop of vas deferens in proximal, portions. Cirrus narrowly ellipsoidal, 41 x 18 Ct, armed with numerous fine, porally directed, hair-like spines. Vas deferens loosely coiled anteroventrally in median portion of segment. Vasa efferentia not observed. Mature ovary 112 i in maximum diameter, transversely elongate, bilobate-the right and left lobes being connected by a slender elongate isthmus; dextral lobe usually further subdivided into anterior and posterior lobules. Vitellarium broadly ellipsoidal, transversely elongate, behind ovary near center of proglottid, about 37 u in transverse diameter. Mehlis' gland situated dorsally between vitellarium and left lobe of ovary. Uterus at first a small indistinct sac; later it becomes roughly U-