Thryssatrema hanumantharaoi, Madhavi, Rokkam, 2012

Madhavi, Rokkam, 2012, Thryssatrema hanumantharaoi n. gen., n. sp. (Digenea: Fellodistomidae) from the longjaw thryssa, Thryssa setirostris (Clupeiformes: Engraulidae), of the Visakhapatnam coast, Bay of Bengal, Zootaxa 3551, pp. 59-64 : 60-62

Thryssatrema hanumantharaoi n.sp.

( Figs. 1–3)

Type host: Thryssa setirostris (Broussonet) , longjaw thryssa , ( Engraulidae : Clupeiformes ).

Type locality: Visakhapatnam coast, Bay of Bengal (17°44'N, 83°23').

Site: Intestine.

Deposited Specimens: NHMUK London holotype NHMUK 2012.7.18.1; Zoological Survey of India, Calcutta, India paratype Regd. no. w 9290/1.

No. of specimens: 20 flukes from 18 infected fish out of 120 examined.

Prevalence: 15%.

Mean intensity: 20/18 = 1.1.

Abundance: 20 /120= 0.17.

Etymology: The genus is named after the host genus. The species is named in honor of the late Professor K. Hanumantha Rao, in recognition of his contributions to the knowledge of helminth taxonomy.

Description. (Based on 6 whole mounts) Body elongate, broad posteriorly, tapering anteriorly, 2,400 – 3,312 (2,878) long, 330–624 (506) wide, maximum width at between vitellaria and ventral sucker. Tegument aspinose, thin, transparent.

Suckers poorly developed, subterminal oral sucker somewhat funnel-shaped, almost square, 88–172 (126) long, 98–156 (130) wide; ventral sucker small, circular, rudimentary, 48–80 (60) in diameter. Sucker ratio 1: 0.34 – 1:0.57 (1:0.48). Forebody highly extensile, length variable depending on degree of contraction during fixation, 234-650 (450) long. Prepharynx absent. Pharynx oval, 60–88 (72) in diameter, major part of it lies dorsal to oral sucker. Esophagus narrow, 80–200 (136) long, bifurcation immediately anterior to ventral sucker. Ceca slender, reach to posterior extremity and end blindly.

Testes two, oval, fairly large, subequal in size, right testis 216–408 (304) long, 120–240 (152) wide; left testis 216–408 (296) long,112–240 (168) wide, symmetrically arranged in posterior half of hindbody, separated by uterine coils; posttesticular space 560–860 (624) long. Distance between ventral sucker and anterior margin of testes 800–1,680 (1,058)). Cirrus sac small, claviform, extends posterior to ventral sucker, 140–310 (212) long, 68–100 (90) wide. Seminal vesicle bipartite, both chambers of same size, in posterior half of cirrus sac. Pars prostatica vesicular; prostatic cells small, numerous. Ejaculatory duct narrow, tubular. Genital pore median, immediately anterior to ventral sucker.

Ovary distinctly 3-lobed, 184–312 (248) long, 120–240 (186) wide, immediately pretesticular, overlapping left testis, at junction of middle and posterior third of hindbody. Mehlis’ gland small, ventral to ovary. Laurer’s canal opens dorsally at level of ovary. Neither uterine seminal receptacle nor seminal receptacle visible, probably overlapped by eggs. Uterine coils extensive fill entire post-testicular space; pass between two testes, and take straight course along median line, ultimately to open into genital atrium. Metraterm small, muscular, lateral and dextral to cirrus sac. Eggs numerous, small, 24 –28 long, 12–16 wide. Vitelline follicles elliptical, forming compact lateral groups anterolateral to testes, overlapping caeca dorsally and ventrally, intruding into intercaecal space. Vitelline zone 400–760 (530) long, commences at distance of 560–1,120 (708) from posterior margin of ventral sucker; two transverse vitelline ducts prominent, join anterior to ovary.

Excretory pore terminal, surrounded by a sphincter. Excretory vesicle V-shaped with long arms reaching level of posterior esophagus.