First record of the family Pseudocerotidae (Platyhelminthes, Polycladida, Cotylea) from the Persian Gulf, Iran

In this paper, two species of cotylean Platyhelminthes are recorded for the fi rst time from Qeshm Island, Persian Gulf, Iran. Pictures are taken from living specimens to illustrate shape and colour, and stained sections and drawings are used to describe shape and organisation of some organs. Morphological characters of Persian Gulf specimens of Tytthosoceros lizardensis Newman and Cannon 1996 are compared to those of the type specimens of this species.


First record of the family Pseudocerotidae
(Platyhelminthes, Polycladida, Cotylea) from the Persian Gulf, Iran

Introduction
Most polyclad fl atworms inhabit coral reefs in tropical and subtropical waters, and are especially species-rich throughout the Indo-Pacifi c. Th ey are found from the littoral to sublittoral zone, and are often associated with other invertebrates (Bolaños et al. 2007).Th e order Polycladida is divided into two groups, Acotylea, which lack a ventral sucker, and which is not recorded from the area until now.Th e second group Cotylea is characterised by possesion of a ventral sucker.Among Cotylea, the family Pseudocerotidae contains many conspicuous and colorful species.Th e diversity of this group, however, is not well known, because their collection, handling, and identifi cation are diffi cult (Hyman 1954(Hyman , 1959;;Newman and Cannon 1994a, b, 1996a, b, 1997, 1998, 2000, 2002;Newman et al. 2003) Th e two pseudocerotids species Tytthosoceros lizardensis and Th ysanozoon sp.have been reported from reef crests and slopes of Queensland and the Great Barrier Reef (Australia) (Newman and Cannon 1996), and were also mentioned in a multimedia CD on fl atworm diversity (Newman and Cannon 2005) as being known from Indonesia, the Philippines, and South Africa.To date, there has been no record of these species from the Persian Gulf and the Gulf of Oman, or other parts of the northern Indian Ocean.In fact, little is known about the diversity and biology of free-living fl atworms from this region, and only a few species have been briefl y mentioned by Newman and Cannon (2005) from the Gulf of Oman.
To close this gap in our knowledge, we carried out a study on the intertidal polyclads of Qeshm Island located in the Straight of Hormoz between the Persian Gulf and the Gulf of Oman (Fig. 1).Among other fl atworm species, members of the family Pseudocerotidae were very conspicuous and are here reported for the fi rst time from the Persian Gulf.

Material and methods
Sampling was carried out during six fi eld trips (November and December 2007, January, May, July and November 2008 ) from 14 locations along the intertidal zone of the, Persian Gulf, Iran (Fig. 1, Table 1).Flatworms were hand-collected and kept in separate sampling containers, and then brought back alive to the laboratory.However, most specimens autolysed during sampling or during fi xation.Th e remaining specimens were photographed in vivo, fi xed on frozen 10% buff ered formalin, for at least 24 hours, and then transferred into 70% ethanol for preservation (Bolaños et al. 2007).
Whole-mounts were stained with acetic Carmine, dehydrated in a graded alcohol series and mounted on microscopic slides using Canada Balsam.Some specimens were embedded in Paraffi n, and 5μm sagittal serial sections were obtained to study the reproductive system.Sections were stained with Mayer's hematoxilin and eosin (Humason 1972).Sections and whole mounts were studied under a compound microscope (ZEISS, Axioplan2, 459312), and a stereomicroscope (Wild, Herbrugg, 124074), respectively.Drawings and measurements were carried out with aid of a camera Lucida.
Specimens are deposited at the Zoological Museum of University of Tehran collection (ZUTC).

Results
Th ree hundreds ninety-nine specimens belonging to fi ve diff erent families of polyclads were collected, of which 80 specimens belonged to Pseudocerotidae.Th ose specimens were identifi ed as belonging to the genera Tytthosoceros and Th ysanozoon.
Fifty-six specimens of this species were collected from two locations (Stations No. 1 and 2, Fig. 1, Table 1).Most specimens were found in groups of up to 20 individuals,     Description.Sizes of specimens range from 22 × 38 to 30 × 46 mm; background color variable, mottled light brown or olive green with cream mottling composed of dots, forming loose transverse streaks medially and laterally, darker medially sometimes with a tinge of light brown medially and on the pseudotentacles; narrow marginal bands, black then grey interrupted with short white transverse streaks of microdots at rim; submargin narrow, either cream or transparent grey (Fig. 2); pseudotentacles earlike, small, cream with mottling of light brown or olive between (Fig. 3); 70-80 cerebral eyes, arranged like a horseshoe, dorsal pseudotentaclular eyes, scattered, with about 35 eyes (Figs 3 and 4); ventral surface of specimens cream with black rims, and very ruffl ed margins; anterior pharynx large and ruffl ed, 1/5 of the body length (8.6 mm), associated with 5-6 pairs of pharyngeal folds; mouth situated in the middle of the pharynx (Fig. 6C); intestine extending posteriorly, but not to the margin of the body; male and female gonopores posterior to pharynx, distinct sucker in mid-body proper (Fig. 5).

Discussion
In the present study, 56 specimens of Tytthosoceros lizardensis and 24 specimens of Th ysanozoon sp. were found on the intertidal zones of the Qeshm Island, Persian Gulf.Identifi cations of the specimens are based on comparison of the specimens with im-  ages, the descriptions and keys of Tytthosoceros lizardensis and Th ysanozoon sp. as provided by Newman andCannon (1996, 2003).Newman and Cannon (1994a, b, 1996a, b, 1997, 1998, 2000, 2002, and 2005) and Newman et al. (2003) supplied an overview over the family Pseudocerotidae in the Indo-Pacifi c region, particularly from Australia, Papua New Guinea and Micronesia, and reported numerous species.Here, the most specious genera are Pseudoceros and Pseudobiceros, but other genera like Bulaceros and Tytthosoceros have also been reported from the Great Barrier Reef, Australia, and Papua New Guinea.To facilitate identifi cation of species, Newman and Cannon (1994) erected six groups defi ned by their respective colour pattern.Based on their specifi c color patterns, Tytthosoceros lizardensis and Th ysanozoon sp.can be assigned to their group four, which contains species of cryptic coloration.
Because of their extremely fragile nature, only a few slides of sagittal sections were obtained, so the specimens of Th ysanozoon could only be identifi ed to genus level, but it might well turn out to represent a new species.Species of Th ysanozoon are found circum-      globally in warm seas, but those from Qeshm Island closely resemble those mentioned in the multimedia CD by Newman and Cannon (2005) as originating from the Red Sea.Th e specimens of T. lizardensis found in the present study were similar to those mentioned in the same multimedia as being reported from Indonesia.As summarized in Table 2, the comparison of the specimens with the original descriptions of T. lizardensis showed some diff erences.However, these diff erences are not important enough to further separate the Persian Gulf specimens at the species level.Specimens of T. lizardensis were only found at two locations in a rubble-rocky and rocky habitat.All specimens collected were associated with and possibly feed on an orange sponge (Clione vastifera).Although careful samplings were carried out six times, specimens of T. lizardensis were only found during one excursion in December 2007.Th is study only covered the intertidal zones, and it is very likely that further studies in the subtidal zone may reveal more species of T. lizardensis and of other species of fl atworms.

Figure 1 .
Figure 1.A Location of the Qeshm Island between the Persian Gulf and the Gulf of Oman B Sampling locations.
intertidal pools, and on an orange sponge (Clione vastifera).Most specimens autolysed during sampling or fi xation and only four specimens remained intact after fi xation procedure.Th e following description is based on those four specimens.

Figure 4 .
Figure 4. Eye arrangements on pseudotentacle in Tytthosoceros lizardensis: A dorsal surface: te pseudotentaclular eyes ce cerebral eyes B ventral surface.

Figure 5 .
Figure 5. Tytthosoceros lizardensis: A Drawing of the ventral surface B Photograph of the ventral surface su sucker mg male gonopore fg female gonopore ph pharynx.

Figure 6 .
Figure 6.Sagittal section of Tytthosoceros lizardensis: A male copulatory system B female copulatory system C pharynx: ma male antrum s stylet sv seminal vesicle p prostate fa female antrum fg female gonopore ce cement gland ph pharynx mo mouth.

Figure 7 .Figure 8 .
Figure 7. Sagittal reconstruction of Tytthosoceros lizardensis: ma male antrum mg male gonopore s stylet sv seminal vesicle p prostate fa female antrum fg female gonopore ce cement gland ph pharynx mo mouth 1cm

Figure 9 .
Figure 9. Live specimens of Th ysanozoon sp.under laboratory conditions.

Figure 12 .
Figure 12.Drawing of ventral surface of Th ysanozoon sp.su sucker mg male gonopore fg female gonopore ph pharynx i intestine.

Figure 13 .
Figure13.Sagittal section of Th ysanozoon sp.: A male copulatory system B female copulatory system ma male antrum s stylet sv seminal vesicle p prostate fa female antrum fg female gonopore ce cement glands ph pharynx.

Table 1 .
Coordinates and types of Sampling locations.