Hexechamaesipho pilsbryi (Hiro, 1936)

Pitriana, Pipit, Valente, Luis, von Rintelen, Thomas, Jones, Diana S., Prabowo, Romanus E. & von Rintelen, Kristina, 2020, An annotated checklist and integrative biodiversity discovery of barnacles (Crustacea, Cirripedia) from the Moluccas, East Indonesia, ZooKeys 945, pp. 17-83 : 17

Hexechamaesipho pilsbryi (Hiro, 1936) Figure 8a-f , Table 1: species no. 51

Chthamalus pilsbryi Hiro, 1936: 227, fig. 3.

Euraphia pilsbryi : Newman & Ross, 1976: 41.

Hexechamaesipho pilsbryi : Poltarukha 1996: 989; Poltarukha 2006: 73-74; Chan et al. 2008: 320, fig. 3; Chan et al. 2009a: 149, fig. 125; Tsang et al. 2013: 188.

Material examined.

Ambon Island: 20 specimens, MZB Cru Cir 054, Hila, 3°34'57.5"S, 128°05'31.9"E, coll. Adin, 20 Sep 2017; 1 specimen, MZB Cru Cir 055, Hatu, 3°43'52.7"S, 128°02'51.4"E, coll. Adin, 20 Sep 2017.

Diagnosis.

Shell with six plates; surface grey with black spots scattered; scutum and tergum deeply interlock forming a sinuous line; cirri I and II with multi-cuspid setae.

Description.

Surface of parietes grey or light brown in colour and spotted with black; orifice rhomboidal (Fig. 8a ); basis calcareous; scutum and tergum strongly articulated, forming sinuous line; scutum elongated, triangular, tergal margin strongly articulated tergum narrow, basi-scutal angle almost 90° (Fig. 8b-c ); cirrus II with multi-cuspid setae; mandible with three large teeth (Fig. 8f ), labrum with row of large teeth. Basal length 8.9-17.0 mm, basal width 10.3-16.4 mm, height 1.0-3.7 mm. Orifice length 4.2-6.9 mm, orifice width 3.6-5.6 mm (measurements for ten specimens are presented in Suppl. material 1: Table S7).

Distribution.

Previously, Hexechamaesipho pilsbryi was reported from Japan (Honshu, Shimoda, Wakayama, Okinawa); Taiwan (Turtle Island, Da Xiang Lang, Shi Ti Ping, Kenting); Philippines (Puerto Galera, Tiwi-Bicol, Boracay); Malaysia (Nexus Beach, Kota Kinnabalu, Sabah) ( Tsang et al. 2013). In the present study, H. pilsbryi was collected from Hatu and Hila on Ambon Island (a map with the occurrence of Hexechamaesipho pilsbryi in the Moluccas is shown in Suppl. material 1: Fig. S2). A previous study of H. pilsbryi indicated that the distribution of this species bridges the junction of the Japan region and the Indo-Polynesian province of Briggs ( Briggs 1974). Molecular results of H. pilsbryi analysed by Tsang et al. (2013) suggested that this species can be divided into two highly diverged lineages: (1) a northern lineage, predominantly distributed in Japan and Okinawa, and (2) a southern lineage, primarily distributed in Taiwan and Southeast Asia. Assuming that we have molecular data of H. pilsbryi in our samples, there is a probability that our samples from the Moluccas include members of the southern lineage.

Remarks.

Hexechamaesipho pilsbryi was first identified from Japan as Chthamalus pilsbryi Hiro, 1936. However, due to the presence of three large teeth on the mandible, a characteristic of the subfamily Euraphiinae , the species was placed in the genus Euraphia ( Nilsson-Cantell 1921). Later, due to the presence of multicuspidate setae on cirrus II, Poltarukha (1996) moved E. pilsbryi to the sub-family Notochthamalinae and determined a new genus, Hexechamaesipho , which had six parietes and a deeply interlocking scutum and tergum. Currently, H. pilsbryi is the only species in the genus.

Figures

Figure 8. Hexechamaesipho pilsbryi (Hiro, 1936) (MZB Cru Cir 055) a upper view b external view of scutum and tergum c internal view of scutum and tergum d maxilla e maxillule f mandible. Scale bars: 4 mm (a); 2 mm (b-c); 0.5 mm (d-f).