Glaucivermis spinosus gen. et sp. n. (Digenea: Zoogonidae) from the Southern Kingfish, Menticirrhus americanus (Linnaeus), in the Coastal Waters of Mississippi

Abstract

Glaucivermis spinosus is described from the intestine and pyloric ceca of Menticirrhus americanus collected near Ocean Springs, Mississippi, in the Gulf of Mexico and adjacent waters. The genus is characterized primarily by having a preacetabular intestinal bifurcation, a preacetabular sinistral genital pore, a bilobed vitellarium, a swelling of Laurer's canal to form the seminal receptacle, and tandem to diagonal testes. It is most similar to the genus Diphtherostomum from which it differs primarily in the arrangement of the testes. Specimens of a new species of zoogonid trematode were collected during the spring and autumn of 1970 from Menticirrhus americanus in water of both high and low salinity near Ocean Springs, Mississippi. Because of the unique arrangement of the testes, a new genus is erected for the worm. Living trematodes were fixed in hot AFA solution and subsequently stained with Van Cleave's hematoxylin. All measurements are given in microns. Glaucivermis gen. n. Diagnosis: Body small, spinose; oral spines present. Oral sucker terminal. Prepharynx short. Bifurcation of esophagus preacetabular. Ceca terminating in or slightly posterior to acetabular zone. Acetabulum without prominent lip. Genital pore sinistral, preacetabular. Testes tandem to diagonal, usually completely in hindbody. Cirrus sac extending into acetabular level; containing large prostatic vesicle and bipartite seminal vesicle. Cirrus with minute papillae. Ovary between anterior and lateral to forward testis, seldom overlapping it. Seminal receptacle a swelling of Laurer's canal. Vitellarium bilobed, near posterior portion of ovary. Uterus filling most of hindbody. Metraterm well developed. Eggs containing miracidia without eyespots. Parasites of marine fishes. Type and only species: Glaucivermis spinosus sp. n. (Figs. 1-5) Description (based on 18 mature specimens): Body usually spindle-shaped, with forebody attenReceived for publication 8 December 1970. * This study was conducted in cooperation with the Department of Commerce, NOAA, National Marine Fisheries Service, under Public Law 88-309, Project No. 2-85-R. uated and posterior end of body usually more pointed than anterior; 412 to 795 long by 119 to 175 in maximum width (at acetabular level). Tegument completely spinose; spines of hindbody short and fine; spines of forebody robust and thornlike, somewhat smaller anteriorly and very short around oral sucker except most anterior row on dorsal side with 9 to 11 (10 on 16 specimens) large globular spines. Numerous small elongated gland cells opening externally, primarily in forebody. Oral sucker funnel-shaped, 51 to 79 long by 49 to 70 wide. Acetabulum weakly developed, 63 to 91 long by 61 to 81 wide. Sucker width ratio 1:1.0 to 1.4. Forebody 45 to 57% of body length. Prepharynx short when evident. Pharynx 28 to 37 long by 19 to 23 wide, with 4 inconspicuous anterior lobes. Esophagus 1.7 to 7.2 times length of pharynx. Testes smooth to somewhat irregular, usually contiguous but occasionally well separated; anterior testis 70 to 98 long by 37 to 81 wide, usually postacetabular, sometimes at acetabular level; posterior testis 67 to 112 long by 44 to 67 wide. Posttesticular space 6 to 17% of body length. Genital pore at or near margin of body. Cirrus sac arcuate, 112 to 216 long by 33 to 44 wide, or 3 to 5 times longer than wide, extending to anterior margin or middle of acetabulum; cirrus when retracted a little more than 1/3 length of sac. Ovary smooth, 58 to 88 long by 42 to 70 wide, usually somewhat dextral, overlapping posterior portion of acetabulum. Vitellarium deeply bilobed, either larger or smaller than ovary. Uterus with proximal end usually filled with sperm, distal end having muscular portion before joining metraterm. Metraterm (= terminal organ) conspicuous, muscular, with fine delicate papillae, 61 to 88 long by 21 to 44 wide, or about 2 to 4 times longer than wide, with conspicuous outpouching near distal end, joining to short genital atrium by short narrow muscular duct. Eggs 24 to 30 long by 12 to 16 wide in mounted specimens, 26 to 34 by 16 to 19 in living ones; egg shell prominent, operculated. Excretory vesicle saccular, epitheliated, usually