Tytthosoceros lizardensis Newman & Cannon, 1996

Maghsoudlou, Abdolvahab & Rahimian, Hassan, 2014, Contribution to the knowledge of cotylean flatworms (Turbellaria, Polycladida) from Iranian coasts: Introducing a new species, with remarks on new records, Zootaxa 3860 (4), pp. 325-342 : 336-340

Tytthosoceros lizardensis Newman & Cannon, 1996

( Figures 8–9 )

Type locality. Heron Island, southern Great Barrier Reef- Australia.

Other localities. Indonesia, Philippines, Papua New Guinea, South Africa ( Newman & Cannon 2005) and Iran ( Khalili et al. 2009).

Location in Iran. Specimens were collected from two intertidal localities of Qeshm Island ( Fig.1 stations 33 and 31). Both stations have sandy-rocky substrate with numerous small and large intertidal pools covered in red and brown algae, sponges and tunicates (Table 1).

Material examined. Eight individuals were examined: three mature specimens as ZUTC platy 1269-71 HS; five specimens as ZUTC platy 1272 S (Table 1). The following description is based on observation from ZUTC platy 1269, unless otherwise stated.

Description. External morphology. Body soft and delicate, long and oval, slightly tapered posteriorly and raised medially ( Figs. 8 A, C). The average size of the fixed specimens is 22 × 13 mm, the largest and smallest specimens 30 × 1.7 and 16 × 10, respectively. Dorsal background darker on the raised middle region, with transverse streaks medially and laterally, mottled with a mixture of chocolate brown, reddish brown or light brown and cream. Body margin with outer narrow whitish grey band and inner black band, a light beige sub-marginal band may be visible ( Fig. 8 A), body margin broken at the edge with short white transverse streaks of microdots. Pseudotentacles small, ear- like, with color pattern similar to the dorsal body, with white tips ( Figs. 8 A, B); dorsal tentacular eyes scattered, with 33–37 eye spots; cerebral eyes horseshoe shaped, containing 55 to 90 ocelli on a whitish grey background. Ventral surface transparent cream, with a grey and black margin, internal structures such as uterus, vasa deferentia, genital pores and pharynx visible from the ventral surface. Pharynx 3.9 mm long, with five to six pairs of simple folds; mouth central ( Fig. 8 D); main intestine extended posteriorly with lateral branches in histological sections ( Figs. 8 D, 9E). One male gonopore located posterior to the pharynx, female pore 800 µm posterior to the male pore. Sucker located ventrally, about 3.5 mm posterior to the female pore, 272 µm long ( Figs. 8 D, 9E). Dorsal epidermis with rhabdites, ventral epidermis without ( Fig. 9 D).

Reproductive structures. Male reproductive system ( Figs. 9 A–C, E) with true seminal vesicle. Muscular seminal vesicle, 44 µm thick, oblong, 390 µm long × 241 µm wide ( Figs. 8 B–C, 9E). Prostatic vesicle ( Figs. 9 A, E) small, oval, 198 µm × 102 µm, somewhat muscular, 21 µm thick, slightly oriented postero-dorsally, prostatic duct joints ejaculatory duct in the middle of the penis ( Fig. 9 E); penis stylet 134 µm × 61 µm, stylet length to width ratio 1: 2.1; male atrium ciliated, wide (120 µm) and shallow (90 µm) ( Figs. 9 B, E). Vas deferens forming a network of thin tubes ( Fig. 8 D), testes scattered ventrally throughout the body ( Figs. 9 D, E). Female system ( Figs. 9 B, C, E) with deep and ciliated atrium; cement glands large; vagina thick and muscular; oviduct full of eggs ( Figs. 9 B, C, E); female gonopore round, 230 µm in diameter ( Figs. 9 B, C, E); ovaries distributed dorsally ( Fig. 9 D).

Remarks. The genus Tytthosoceros belongs to the family Pseuodocerotidae, erected by Newman and Cannon (1996) based on specimens from the Central and Eastern Indo-Pacific (the Great Barrier Reef, Australia, Papua New Guinea, and the Philippines). Most species of the family occur in tropical and subtropical waters of the Indo- Pacific region ( Hyman 1954). So far, three species have been assigned to the genus Tytthosoceros : T. inca Baeza, Véliz, Pardo, Lohrmann and Guisado, 1997 ; T. lizardensis Newman & Cannon, 1996 ; T. nocturnus Newman & Cannon, 1996 .

Based on color and color patterns for pseudocerotids ( Newman & Cannon 1996), T. lizardensis belongs to the fourth group, whichis characterized by spots, dots, and mottling by spots ( Newman & Cannon 1994). With regard to the overall body shape, color patterns and anatomy of male reproductive system, our observations agree well with descriptions of Newman and Cannon (1996a) and Khalili et al. (2009).

The distribution of T. lizardensis is assumed to be rare on the reef crest and subtidal areas, on the other hand it is supposed to be abundant on intertidal areas ( Newman & Cannon 1996). Khalili et al. (2009) have already reported the presence of T. lizardensis in the Iranian waters of the Persian Gulf ( Fig. 1 , stations 31 and 33). Six of the 38 stations ( Fig. 1 , stations 30–35) studied here are same those of Khalili et al. (2009) where we again found T. lizardensis in two of the six stations ( Fig. 1 , stations 31 and 33). Consequently, it’s reasonable to suppose that the distribution of this species on the southern coasts of Iran (the Persian Gulf and Gulf of Oman), for some reasons, is limited to the eastern side of Qeshm Island (Persian Gulf, Fig. 1 , stations 31 and 33). In terms of the SACFOR abundance scale for animals greater than 15 cm ( Connor et al. 1997), this species was distributed frequently on the aforementioned Island.

Khalili et al. (2009) found their specimens associated with orange sponge ( Cliona vastifica ); we collected our specimens under rocks and in tidal pools, mostly covered with red algae (Solieria) and the sponge, Gelliodes carnosa ( Fig. 10 D).

Figures

FIGURE 1. Map of the Western Indo-Pacific including the Persian Gulf and Gulf of Oman. Sampling stations are indicated by numbers (stations 30 – 35 located at Qeshm Island).

FIGURE 8. Tytthosoceros lizardensis, ZUTC platy 1269: (A) Dorsal view of living specimen (B) drawing of tentacles with eyes (C) drawing of a whole cleared specimen, dorsal view (D) drawing of the ventral view. Abbreviations: ce, cerebral eye; cg, cement glands; fp, female pore; m, mouth; mp, male pore; ph, pharynx; su, sucker; te, tentacular eyes; ut, uterus; vd, vas deferens.

FIGURE 9. Tytthosoceros lizardensis, ZUTC platy 1269: (A – D) Haematoxylin-eosin stained sections (A – C) male and female reproductive systems (D) testis and ovaries showing distribution (E) reconstruction of the male and female reproductive systems. Abbreviations: cg, cement glands; cma, ciliated male atrium; fp, female pore; i, intestine; ild, intestinal lateral diverticulum; m, mouth; ml, muscular layer; mp, male pore; o, ovaries; ov, oviduct; ph, pharynx; pv, prostatic vesicle; su, sucker; sv, seminal vesicle; ts, testis; ut, uterus.

FIGURE 10. Field photography of Iranian polyclads presented here: (A – C) marine polyclads associated with ascidians (A) Maritigrella makranica (B) Pseudobiceros uniarborensis (C) Thysanozoon brocchii (D) Tytthosoceros lizardensis along with red algae.