Peltogaster aff. ovalis Krüger, 1912

Jung, Jibom, Yoshida, Ryuta & Kim, Won, 2019, Ophiacantha scissionis Lee & Stöhr & Bae & Shin 2019, sp. nov., Zoological Studies (Zool. Stud.) 58 (33), pp. 1-12 : 11

Peltogaster aff. ovalis Krüger, 1912 ( Fig. 5D, 5E )

Material examined: On Pagurus ochotensis : 1 Ind., Busan, 35°8'16.83"N 129°9'37.01"E, fishing trap, 31 Jan. 2016, Coll. Jung J, MADBK 160714_013, host: male, SL 10.2 mm.

On P. parvispina : 1 Ind., Goseong, 22 Nov. 1980, Coll. Rho BJ, EWUNHM DP 20151217063, host: female, SL 5.3 mm.

On P. rathbuni : 1 Ind. (2 externae), Yangyang, 21 May 2002, EVOSYS 260720#013, host: male, SL 12.5 mm.

On P. rubrior : 1 Ind., Busan, fishing trap, 15 Jul. 1972, EVOSYS 260717#012, host: male, SL 9.8 mm; 1 Ind., Busan, 9 Feb. 1971, EWUNHM DP 20151125023, host: female, SL 11.7 mm; 1 Ind. (3 externae), Seogwipo, 13 Jul. 1972, fishing net, Coll. Lee KS, EVOSYS 260717#038, host: female, SL 19.4 mm; 1 Ind. (2 externae), Seogwipo, 33 ° 14'10.13"N 126 ° 31'2.71"E, 14 Nov. 2008, Coll. Kim SH, MADBK 160717_007, host: male, SL 19.2 mm; 1 Ind., Yeosu, St. 1, 21 Jun. 2002, EVOSYS 260717#033, host: male, SL 19.1 mm.

Hosts: P. ochotensis , P. parvispina , P. rathbuni , P. rubrior ( Paguridae ).

Distribution: Korea.

Remarks: The externa of the examined materials had similar morphological characteristics to that of Peltogaster ovalis specimen described by Krüger (1912), including an oval body, terminally located elevated projection of the mantle aperture, U-shaped mantle opening, and a chitinous shield. However, no P. ovalis were reported on these four host species (i.e., Pagurus ochotensis , P. parvispina , P. rathbuni , and P. rubrior ) in the previous study. We could not obtain the sequencing data on the present materials. Therefore, we tentatively identified these species as Peltogaster aff. ovalis . Additional information and further studies, such as histological examination and larval morphology, are necessary to confirm the identity of these species.

The morphological characteristics of the specimen attached to Pagurus rathbuni (EVOSYS 260720#013) were slightly different to these of Peltogaster aff. ovalis in Yoshida et al. (2014). However, the main characteristics, such as oval shape of the whole externa, elevated mantle located on the terminal margin of the externa, and U-shaped mantle opening are similar to those of P. aff. ovalis from Yoshida et al. (2014). Therefore, we identified the specimen as P. aff. ovalis .

Some of the examined specimens (MADBK 160717 _ 007, EVOSYS 260717 # 038 EVOSYS 260720#013) had two and three externae (28.57% and 14.29% of total individuals, respectively), whereas others had a single externa. In the original description of Peltogaster ovalis by Krüger, 1912, and in the re-description of P. aff. ovalis by Yoshida et al. (2014), there are no descriptions of multiple externae for this species. However, variation in the number of externae has been reported in previous studies. For example, Reinhard (1942) reported that some specimens of P. paguri on Pagurus pubescens produced multiple externae, whereas most possessed a single externa. In addition, Høeg and Lützen (1985) showed that some Peltogaster curvatus members have a single externa on their host Pagurus cuanensis in Scandinavian waters, whereas in the Mediterranean Sea, they had two to four externae on one-third of their two hosts ( P. cuanensis and P. prideaux ). Therefore, the multiple externae of these specimens were regarded as the result of an invasion of different larvae or from asexual budding.

Figures

Fig. 5. Korean peltogastrids. A, Peltogaster lineata on Pagurus brachiomastus and its mantle, MADBK 430101_001; B, Peltogaster postica on Pagurus filholi, MADBK 160707_009; C, mantle of B; D, Peltogaster aff. ovalis on Pagurus rathbuni, EVOSYS 260720#013; E, mantle of D; F, G, Peltogaster aff. reticulatus on Pagurus proximus and its mantle, MADBK 160718_040; H, Peltogaster sp. 2 on Areopaguristes nigroapiculus and its mantle, EVOSYS 260510#008; I, Peltogasterella gracilis on Pagurus pectinatus, MADBK 160715_016; J, mantle of I; K, Peltogasterella aff. gracilis on Porcellanopagurus nihonkaiensis, MADBK 160730_002.