Pakistan J. Parasitol., 68; December 2019: 39-44

METAMICROCOTYLA CRIBBI SP. N. (: ), INFECTED TO THE GILLS OF MOOLGARDA SEHELI FORSSKAL, 1775 (MUGILIDAE) FROM THE COASTAL WATERS OF SINDH AND BALOCHISTAN

Mehtab Ibrahim1, Nasira Khatoon1, Aly Khan2 and Rana Hadi3

1Department of Zoology, University of Karachi, Karachi-75270, Pakistan 2C.D.R.I. Pakistan Agricultural Research Council, University of Karachi, Karachi-75270, Pakistan 3Department of Zoology, Jinnah University for Women, Karachi-74600

Abstract

Monogenean biodiversity of piscine is poorly known from the Arabian Sea of Pakistan. This study describes the occurrence of cribbi n.sp. (Monogenea: Microcotylidae) recovered from the gill filaments of mullet, Moolgarda seheli stocked from Karachi and Makran Coastal water. The new possesses the following characters such as body elongated measuring 7.36-12-20 with the broadest width at the position of ovary in the middle part of the worm. The two septate anterior suckers are oval shaped. No prepharynx but with spherical, small pharynx. Esophagus out growth are inconspicuous. Genital atrium with large recurved spines. Clamps are 21-31 pairs. Testes numerous. Vagina is absent. The Metamicrocotyla (Yamaguti, 1953) is being recorded for the first time from of Pakistan. This study also records the first report on occurrence of monogenea from fishes of Makran Coast.

Keywords: Monogenea, Metamicrocotyla cribbi n.sp., , Gills, Pakistan coastline.

INTRODUCTION

Mugilids or more commonly the grey mullets occur in brackish, fresh and salt waters of tropical and subtropical areas around the world. Mullets with commercial values serve as one of the basic cheap source of protein for population of many regions of Pakistan particularly of Balochistan province. The parasitic biodiversity of monogenean worms is unsatisfactorily explored from the Arabian Sea. Little studies have been reported on monogeneans from fishes in Pakistan (Hadi and Bilqees, 2010, 2011, 2012; Hadi et al., 2011, 2019). Monogeneans are ectoparasitic helminths that survive on the expense of a wide range of aquatic vertebrates specially are parasites of fins, skin and gills of fishes with some exceptional species that occur internally to their hosts (Park et al., 2007). Gill monogeneans have been recorded to be one of the major cause of parasitic infection in cultured fishes (Kang et al., 2016). These worms are highly host specific with an estimation of 25,000 species making the group highly diverse (Theisen et al., 2017). Mass mortalities in grey mullets by the monogenean infestations have been reported (Paperna et al., 1984). Yamaguti (1953) erected the genus Metamicrocotyla with the type species M. bora in Mugil cephalus from Macassar. Later on the following species were added to the genus which are; M. filiformis Yamaguti, 1953; M. cephalus (Azeem, 1939) Hargis, 1954; M. macracantha (Alexander, 1954) Koratha, 1955; M. mugulis Yamaguti, 1968; M. inoblita Buhrnheim, 1970; M. manaarensis Unnithan, 1971 and M. pacifica Bravo-Hollis, 1982 recovered from mullets of different spots globally. These worms are very similar to the representatives of genus . Yamaguti introduced this genus mainly based on complete absence of vagina and further added that vanishing of the vitellaria to the posterior part of the body is of significant character (Hargis, 1956). WoRMS enlisted ten valid species of the genus. Another mullet Moolgarda seheli has been studied to host a new species of Metamicrocotyla.

MATERIALS AND METHODS

For a period of nearly one year from October 2018-August 2019 specimen of host fish were sampled from two areas of Pakistan coastal line and brought to the laboratory of Parasitology, University of Karachi (Fig. 1). Most of fish were dissected fresh immediately after collection and rest of samples were in frozen state. Scales, skin, fins, eyes, nostrils, mouth and gills were observed macroscopically for any parasitic infection. Gills were removed and kept in petri dish containing saline. Wet smear of mucus from gills were observed microscopically. Worms were detached from filaments carefully with fine needle and allowed them in salt solution for relaxation. Fixed them in Alcohol- Formlin-Acetic acid (AFA) solution for 10-24 hours, stained in Mayer’s alum carmine, dehydrated in increasing strength of ethanol (70%, 90%, 100%), cleared in clove oil and removed the excess oil in xylene. Finally mounted with Canada balsam permanently. 40 Ibrahim et al

Diagrams were made by camera Lucida attached to a light microscope. Nikon photomicroscope was used to prepare photographs at different magnifications of X40, X100, X200, X400. All measurements are given in millimeter. Holotype and Paratype slides are deposited in Reference Museum of Department of Zoology, University of Karachi, Karachi-75270.

Fig. 1: Map showing the study area.

RESULTS

Total 142 fish were dissected among which 29 were positive with 57 monogenean worms. Fish host was confirmed from “Field Identification Guide to the Living Resources of Pakistan” (Psomadakis et al., 2015). Helminths were identified through previous reported publications and Systema Helminthum of Yamaguti (1963).

Metamicrocotyla cribbi sp.n. (Figs. 2-4)

Type-host: Moolgarda seheli (Forsskal, 1775) (Mugilidae), bluespot mullet Type-locality Off Karachi Coast (24°94'46.218"N, 67°00'56.15"E), Arabian Sea Other locality Off Makran Coast (25°40'20.39"N, 66°36'19.79"E), Arabian Sea Site of infection: Gills Prevalence: 20.42% Mean intensity: 1.96 Etymology: Named in honor of Dr. Thomas Cribb, Australia for his extensive contribution in the field of parasitology.

Family Microcotylidae Taschenberg, 1879 Genus Metamicrocotyla Yamaguti, 1953 METAMICROCOTYLA CRIBBI SP. N. (MONOGENEA: MICROCOTYLIDAE), INFECTED TO THE GILLS 41

Metamicrocotyla cribbi sp.n.

The slender, elongated, dorsoventrally flattened body is divided into narrower anterior and posterior region while wider at the middle part measuring 7.36-12.24 in length and has maximum width at the ovarian level measuring 0.72-1.4. The anterior end is rounded with a ventroterminal mouth. The two anterior oval shaped suckers are septate. Each buccal organ measures 0.4-0.7 in length and 0.10-0.18 wide. Two rows of minute spines are seen in each oral sucker. Anterior to suckers are present three adhesive structures. Prepharynx is absent. Spherical to rounded pharynx is present which measures 0.045-0.16 in length and 0.037- 0.14 is wide. Esophagus with inconspicuous outgrowth. The intestine bifurcates at the level of genital atrium into two intestinal crura which do not unite posteriorly with left caecum being shorter then right one. Right caecum extend deep into haptor. Genital aperture is median which is structured by 17-19 pairs of large recurved spines much like in a brush shape. The genital atrium measures 0.10-0.16 in length while 0.10-0.20 in width. Each group of atrial spines consist of one row of 8-9 anterior spines and 9-11 posterior spines arranged in two rows. Genital atrial spines are 0.045-0.2 long and 0.0075-0.06 wide. Vitellaria consisting of small follicles which are dense near intestinal crura at the position of genital atrium in the midline filling the space between caeca of intestine from the anterior of ovary while poorly developed in opisthaptor. Ovary is large, tubular with two loops upward giving it an appearance of letter Y measuring 0.225-1.40 in length while 0.031-0.12 is the width. Vagina is not present. The small, rounded but somewhat irregular postovarian, intercaecal testes are numerous almost 100-120 which are loosely packed till the position where vitellaria become scarce. Neither cirrus nor cirrus pouch were visible. At the posterior of the worm, anterior to haptor, lies ventrally a large, conspicuous, elliptical to globular structure which is spread over the entire breadth of the body seen in almost all specimens measuring 0.24-0.91 in length and 0.27-0.31 in width. Even in some specimen it was observed to protrude out of the body forming bulges. This structure is though clear in all specimen but more conspicuous in mature worms as compare to immature ones. Maturity of worms was detected from the development of genital and reproductive structures. Posterior part of the worm consists of a symmetrical opisthaptor by which the parasite get attach to the host gills. Haptor measures 1.20 in length while 0.52-1.05 is the diameter. There are two rows of clamps one row for each side. Clamps are similar in shape and size. Each clamp is 0.030-0.072 in length and 0.030-0.031in width. There are 21-31 pairs of clamps in two rows of opisthaptor. The shape of the haptor varies with the relaxing state of the worm. Eggs are not seen though a coiled structure with a bulbus end at one side was observed only in one specimen near to the genital atrium. General morphology agrees with the description given by Yamaguti (1953) for Metamicrocotyla spp., and all of which are unique to a single new species.

DISCUSSION

Differential diagnosis for Metamicrocotyla cribbi n.sp. Here we have compared the new species with the other closely related Metamicrocotyla spp. recorded previously from different localities (Table 1). The measurements for M. macracantha (Alexander, 1954) Koratha, 1955 are taken from the published record of Kohn et al., 1994. Metamicrocotyla cribbi n.sp. has in common with Metamicrocotyla bora Yamaguti, 1953 the same number of genital atrial spines but differs by having larger sized spines, greater number of testes, greater number of clamps. The hosts and locality are also different. The new species is different from Metamicrocotyla filiformis Yamaguti, 1953 by having greater length and number of genital atrial spines, greater testes number, less number of clamps, different host and locality. Metamicrocotyla cribbi n.sp. is very close to Metamicrocotyla macracantha (Alexander, 1954) Koratha, 1955 by having a globular structure anterior to the haptor but this structure is larger in the new species measuring 0.24-0.91 in length and width 0.27-0.31 while in M. macracantha it measures 0.195-0.44 by 0.18- 0.44. This globular to elliptical body in the new species is covering the entire breadth of the worm protruding as bulges outside whereas, in M. macracantha it lies in between the intestinal caeca. Metamicrocotyla cribbi n.sp. is also different by having lesser number of clamps, greater genital atrial spines length and number. The hosts and locality also differs in these both species of Metamicrocotyla.

42 Ibrahim et al

b

c d

Fig. 2(a-d): camera Lucida drawing showing a. Holotype b. Genital atrium spines c. Enlarged spine d. Clamps

3 4

Fig. 3: Photomicrographs showing the entire worm. Fig. 4: Photomicrographs showing the enlarged haptor. METAMICROCOTYLA CRIBBI SP. N. (MONOGENEA: MICROCOTYLIDAE), INFECTED TO THE GILLS 43

Table 1. Comparison of metrical data of Metamicrocotyla cribbi n.sp. with the similar Metamicrocotyla spp. recorded from water of different regions.

Monogenean Metamicrocotyla Metamicrocotyla Metamicrocotyla Metamicrocotyla cribbi n.sp. bora filiformis macracantha

Author Yamaguti, 1953 Yamaguti, 1953 (Alexander, 1954) Koratha, 1955

Host Moolgarda seheli Mugil cephalus Mugil cephalus Mugil cephalus

Locality Off Karachi & Makran Macassar Macassar Gulf of California, Coast (Pakistan) Mexico & Florida

Source Present study Published record Published record Published record

Total Body Length 7.36-12.24 10.5-13 12 5.13-12.12

Body width 0.72-1.4 1.23-1.26 0.36 0.77-1.44

Buccal organ length 0.4-0.7 0.071-0.081 0.06 0.041-0.068

Buccal organ width 0.10-0.18 0.045-0.06 0.045 0.042-0.072

Pharynx length 0.045-0.16 0.045 0.033 0.048-0.076

Pharynx width 0.037-0.14 0.033 0.03 0.036-0.061

Genital aperture length 0.10-0.16

Genital aperture width 0.10-0.20

Genital atrial spines length 0.045-0.2 0.065-0.11 0.04-0.05 0.036-0.084

Genital atrial spines width 0.0075-0.06

Number of testes 100-120 Over a dozen 70 40-124

Length of ovary 0.225-1.40

Width of ovary 0.031-0.12

Length of haptor 1.2 1.3 0.659-1.758

Width of haptor 0.52-1.05 0.403-1.32

Number of clamps 42-62 54 101 26-67

Length of clamps 0.06-0.072 0.029-0.12

Width of clamps 0.027-0.031 0.045-0.09 0.075 0.043-0.195 44 Ibrahim et al

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(Received in October 2019 and accepted for publication in November 2019)