Dendromonocotyle citrosa Vaughan, Chisholm & Christison, 2008, n. sp.
Creators: name: Vaughan, David
name: Chisholm, Leslie
name: Christison, Kevin
Publisher: name: Zenodo
Year: 2008
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Monogenea
Monocotylidea
Monocotylidae
Dendromonocotyle
Dendromonocotyle citrosa

description: Dendromonocotyle citrosa n. sp. (Figs. 1, 2 A, 3, 4A, 4B)
Type host: Dasyatis chrysonota (Smith).
Additional host: Himantura gerrardi (Gray).
Type locality: Two Oceans Aquarium, Victoria & Alfred Waterfront, Table Bay Harbour, Cape Town, South Africa.
Additional locality: uShaka Sea World, Durban, South Africa.
Site on host: Dorsal skin surface.
Materials deposited: SAMCTA 29451 (holotype), SAMCTA 29452 (2 paratypes), SAMCTA 29453, 29454 (3 vouchers), AHC 29170–29171(2 paratypes), AHC 29178 (1 voucher), BMNH 2007.2.21.12 (1 paratype), BMNH 2007.2.21.11 (1 voucher).
Etymology: This species is named for the likeness of the haptor to a halved citrus fruit.
Description. Based on 6 flattened adult specimens collected from D. chysonota. Total body (Fig. 1 A) 2998 ± 563 (2390–3600, n = 6) long. Body-proper 2280 ± 290.7 (2000–2550, n = 4) long and 1568 ± 102.3 (1500–1750, n = 6) maximum width at level of testis. Haptor diameter 2195 ± 89.6 (1330–2800, n = 6), divided into 8 peripheral and 1 central loculus (Fig. 1 A). Haptoral rim with 56 marginal haptoral papillae each armed with between 7 and 9 sclerites (Fig. 1 E). Hamuli absent. Anterior loculus pair with 6 marginal haptoral papillae each, anterolateral and posterolateral loculus pairs with 7 associated marginal haptoral papillae each, posterior loculus pair with 8 marginal haptoral papillae each (Figs 1 A, 2A). Fourteen marginal hooklets (Fig. 1 G) 9 ± 1.1 (8–10, n = 5) long distributed in marginal valve symmetrically between every 4 marginal haptoral papillae (Figs 1 A, 2A). Terminal papillary sclerite as illustrated (Fig. 1 F). Radial septal sclerites uniform (Fig. 1 C). Tripartite sclerites observed in most specimens at junction of radial septa and inner-ring septum (Fig. 1 D). Mouth ventral, subterminal with subterminal groove anterior to mouth (Fig. 1 A). Four pairs of anterolateral gland duct openings (Fig. 1 A). Eyespots situated anterodorsally to pharynx. Pharynx 286 ± 19.6 (189– 368, n = 6) long, and 179 ± 33.6 (129–229, n = 6) wide. Dendritic intestinal caecum, pigmented, with thick lobes extending from anterior, level with pharynx to both posterior marginal lobes of body proper (Fig. 1 A). Single testis 243 ± 22.2 (210–260, n = 4) long, and 364 ± 32 (312–390, n = 5) wide. Vas deferens originates from left side of testis, running anteriorly, dorsal to ovary, and ventral to portion of dendritic intestinal caecum before passing dorsal to vagina and dorsolaterally to ejaculatory bulb (Fig. 1 A). Seminal vesicle originates level to ejaculatory bulb and loops at its distal end before narrowing and entering the distal portion of ejaculatory bulb. Ejaculatory bulb 190 ± 21.6 (170–220, n = 4) long, and 193 ± 20 (180–231, n = 6) wide. Male copulatory organ straight, sclerotised, extending to level with distal portion of ootype. Male copulatory organ (Fig. 3 A) 327 ± 7.3 (315–337, n = 6) long, and 9 ± 0.6 (8–9, n = 4) wide. Distal portion of male copulatory organ with distinct sclerotised filament (Figs 3 B, 4A, 4B). Muscular sheath 58 ± 5 (50–60, n = 4) wide, surrounds entire length of male copulatory organ (Fig. 3 A). Ovary 220 ± 102 (110–310, n = 3) long, and 540 ± 50.3 (470–590, n = 4) wide, conspicuous and roughly ovoid to bi-lobular, immediately anterior to testis (Figs 1 A, 3C). Loops intestinal caecum dorsoventrally. Ootype 342 ± 69.2 (262–387, n = 3) long, ventral to male copulatory organ. Egg tetrahedral (Fig. 3 C) Side length 95 ± 18.0 (80–115, n = 3). Egg filament 120 ± 14.1 (110–130, n = 2) long extends from 1 pole. Mehlis glands not observed. Vaginal pore present on left side of body, level to ejaculatory bulb (Fig. 1 A). Vagina distinct, 377 ± 28.9 (360–410, n = 5) long, with bell-shaped muscular proximal portion (Fig. 3 C), which narrows immediately before entering seminal receptacle. Seminal receptacle 153 ± 27.3 (120–181, n = 5) long, and 103 ± 18.3 (80–131, n = 5) wide. Duct from seminal receptacle to oviduct not seen. Transverse vitelline duct not observed in specimens off D. chrysonota but visible in specimens off H. gerrardi running laterally over ovarian branch to base of ootype and just posterior to proximal portion of sclerotised vagina. Vitellarium obscured by thick lobes of intestinal diverticulum.
Remarks. Dasyatis chrysonota, from which D. citrosa from Two Oceans Aquarium was removed, was originally collected from the Struisbaai area near Cape Agulhas on the south coast of South Africa. The infection was observed in the live aquarium exhibit only and no wild D. chrysonota have been examined for this parasite. Dendromonocotyle citrosa was not found on Dasyatis brevicaudata (Hutton) or Myliobatis aquila (Linnaeus) which were kept in the same exhibit. Measurements of Dendromonocotyle citrosa off D. chrysonota are compared to those off H. gerrardi (Table 1). The specimens from H. gerrardi are smaller in total length than those from D. chrysonota. The spiral filament did not extend as far along the male copulatory organ proximally in the worms from H. gerrardi as it did in some specimens from D. chrysonota (c.f. Figs 4 A, 4B). The morphology of marginal hooklets also differs slightly (c.f. Fig. 1 G). Therefore, while some variation was seen between the 2 groups of worms, we did not deem these differences significant enough to erect a new species for worms off H. gerrardi. Molecular methods were used to determine whether the specimens were identical but we failed to get sequence from material collected off H. gerrardi.
Dendromonocotyle citrosa can be distinguished from the other species in the genus by the morphology of the distal end of the male copulatory organ and the highly muscular proximal portion of the vagina.
description: Published as part of Vaughan, David, Chisholm, Leslie & Christison, Kevin, 2008, Overview of South African Dendromonocotyle (Monogenea: Monocotylidae), with descriptions of 2 new species from stingrays (Dasyatidae) kept in public aquaria, pp. 26-44 in Zootaxa 1826 on pages 27-32, DOI: 10.5281/zenodo.183100