Eumunida smithii Henderson, 1885

Komai, Tomoyuki, Tsuchida, Shinji & Fujiwara, Yoshihiro, 2023, Squat lobsters of the superfamily Chirostyloidea (Decapoda: Anomura) from seamounts on the Nishi-Shichito and Mariana ridges, North-West Pacific off Japan, with descriptions of two new species, Zootaxa 5293 (1), pp. 45-73 : 55-59

Eumunida smithii Henderson, 1885

[New Japanese name: Usuiro-tsuno-koshiori-ebi]

( Figs. 5A , 6 , 7 )

Eumunida smithii Henderson 1885: 413 [type locality: off Kei Islands, Indonesia, 236 m]; 1888: 169, pl. 5, fig. 5a, b.— Puillandre et al. 2011: 330, fig. 2.— Macpherson 2013: 291 (see complete synonymy).— Macpherson et al. 2020: 490 .

Eumunida propior Baba, 1988: 9 , fig. 2 [type locality: SW Luzon, the Philippines].

Eumunida parva de Saint Laurent & Macpherson, 1990: 257 , figs 2a, 11a–k, 12b, c [type locality: New Caledonia].— Baba et al. 2009: 37, figs. 18, 19.

Eumunida (Eumunidopsis) karubar de Saint Laurent & Poupin, 1996: 379 , figs 9b–f, 10b [type locality: off Kei Islands , Indonesia].

Not Eumunida smithii .— Parisi 1917: 6. = Eumunida dofleini Gordon, 1930 .

Identity questionable:

Eumunida smithii .— Yokoya 1933: 67.

Material examined. JAMSTEC 105683, 1 male (cl 4.4 mm, DNA voucher), R / V Kaimei, KM20-10 C, KM-ROV #123 , Shoho Seamount, Nishi-Shichito Ridge, 32°19.39’N, 138°44.48’E, 456.3 m, 28 November 2020, associated with hydrocoral pick up by using manipulator; JAMSTEC 105849, 1 male (cl 3.6 mm), 1 female (cl 4.3 mm), 1 female (cl 4.9 mm, DNA voucher), 1 ovigerous female (cl 5.8 mm), 1 juvenile (cl 3.0 mm), KM20-10 C, KM-ROV dive #126, Shotoku Seamount, Nishi-Shichito Ridge, 30°47.26’N, 138°33.78’E, 316.9 m, 1 December 2020, associated with hydrocoral pick up by using manipulator .

Diagnosis. Carapace anterolateral margins (anterior to cervical groove) armed with 2 pairs of spines; branchial margins each with 3 small spines; gastric region unarmed; dorsal surface without secondary striae between main transverse striae or ridges; posterior part with 4 or 5 complete or almost complete transverse ridges or striae. Thoracic sternite 4 unarmed. Pleon without secondary striae; pleomere 2 anterolateral margins each produced into strong spine; pleomeres 2–5 each with rudimentary pleopods in males. Antennal peduncle article 2 with elongate distomesial spine reaching midlength of peduncular article 4 and short distolateral spine; article 3 with long distomesial and small distolateral spines; article 4 with tiny distomesial and longer, slender distolateral spine. Maxilliped 3 merus unarmed on dorsodistal margin; ventral margin with 2 unequal spines on distal 0.4 of ventral margin. Cheliped merus with 3 longitudinal rows (dorsal, dorsomesial and ventromesial) of strong spines, surfaces squamous; carpus with 2 distal and 1 subdistal spines; palm dorsal surface with covering of short setae, obscuring surface; ventral surface squamous, devoid of ventral pad, occasionally armed with row of small, basally widened spines adjacent to lateral margin; dactylus subequal in length to palm. Pereopods 2–4 relatively stout; pereopods 2 and 3 ischia each with 1 small spine on dorsal margin; meri with row of spines on dorsal margin and with 1 strong ventrodistal spine followed by transverse ridges on ventral margin; carpi with 1 strong extensor distal spine followed by row of smaller spines; propodi with pair of corneous spines on flexor distal margin, followed by row of 6–9 corneous spines on flexor margin; dactyli 0.6 times as long as propodi, each with row of 9 or 10 corneous spines. Pereopod 4 with row of spines on distal half of dorsal margin and on lateral surface.

Colouration in life. Body yellow-brown, paler on pleon; cornea dark gray-brown; chelipeds also yellow-brown generally, reddish at base of dactylus; palm whitish; spines on cheliped merus sometimes reddish; ambulatory legs transparent, with tinge of yellow-brown on meri ( Fig. 5A ).

Distribution. Taiwan, the Philippines (off northern Mindanao, off southwestern Luzon, northeast of the Sulu Islands), Indonesia (Kei Islands), Papua New Guinea, New Caledonia, Tuamotu Archipelago; 96–1245 m ( Macpherson et al. 2020). Newly recorded from Japanese waters (see “Remarks”).

Ecology. The present specimens were collected with colonies of unidentified hydrocoral (cf. Fig. 8 ), suggesting possible association.

Remarks. Eumunida smithii was originally described on the basis of the unique holotype from off Kei Islands, Indonesia, by Henderson (1885). Henderson (1888) provided a more detailed account of the species along with illustrations. Since then, several records were made from various Indo-West Pacific localities under this name ( Balss 1913; Parisi 1917; Van Dam 1933; Baba 1988), but de Saint Laurent & Poupin (1996) established the identity of E. smithii , with clarification of incorrect identifications in the previous studies, and synonymizing E. propior Baba, 1988 with E. smithii . Puillandre et al. (2011) revised further specific identities of taxa within Eumunida using both morphological and unlinked molecular markers (mitochondrial COI and nuclear 28S genes) and concluded that E. parva de Saint Laurent & Macpherson, 1990 (originally described from New Caledonia) and Eumunida (Eumunidopsis) karubar de Saint Laurent & Poupin, 1996 (originally described from the Banda Sea, Indonesia) were also synonymous with E. smithii .

Morphologically, the present specimens agree well with E. smithii rediagnosed by de Saint Laurent & Poupin (1996) and Puillandre et al. (2011) (see above “Diagnosis”). In this study, partial fragments of COI and 16S rRNA genes of two specimens from two different localities (Shoho and Shotoku seamounts) were sequenced and were compared with COI gene sequences referred to as E. karubar (nine sequences), E. parva (10 sequences) and E. smithii (two sequences), available in the GenBank database ( Table 1 ). Genetic divergences of COI gene between our specimens and the specimens registered in the GenBank database (except for EU243350, referred to E. smithii ; Table 1 ) are 0.9–1.8% (JAMSTEC 105683) and 1.9–2.4% (JAMSTEC 105849), suggesting that the voucher specimens represent the same species (cf. Puillandre et al. 2011). As has been already reported by Puillandre et al. (2011), the genetic divergence between the specimen (EU243350, attributed to E. smithii ) and the other specimens is greater, ranging from 1.8–3.7%.

Sequence data of the 16S rRNA gene was first obtained for E. smithii in this study. 16S rRNA gene sequences are available for five species of Eumunida in the GenBank ( Table 1 ). Interspecific genetic divergence within Eumunida ranges from 1.8 to 5.7% and that between E. smithii and the other five species ranges from 2.4 to 5.5% ( Table 3 ). Intraspecific genetic divergence between the two specimens of E. smithii is very low (0.4%), being well consistent with the COI genetic divergence.

Yokoya (1933) recorded Eumunida smithii from two Japanese localities (east of Shimoda, Izu Peninsula, and south of Goto Islands, East China Sea). The record remains to be confirmed because Yokoya (1933) did not provide enough information on the morphology of his specimens. De Saint Laurent & Poupin (1996) clarified that the Japanese record of Eumunida smithii by Parisi (1917) actually represented E. dofleini Gordon, 1930 . The present specimens represent the first certain record of E. smithii from Japanese waters.

Figures

FIGURE 5. A, Eumunida smithii Henderson, 1885, ovigerous female (cl 5.8 mm), JAMSTEC 105849; B, Eumunida treguieri de Saint Laurent & Poupin, 1996, juvenile (cl 5.5 mm), JAMSTEC 106775. Habitus in dorsal view, showing colouration in fresh condition.

FIGURE 6. Eumunida smithii Henderson, 1885, ovigerous female (cl 5.8 mm), JAMSTEC 105849.A, carapace, pleomeres 1–3 and cephalic appendages, dorsal view; B, left antenna, ventral view (flagellum partially omitted); C, left maxilliped 3, merus and carpus, lateral view (setae omitted); D, right cheliped, merus, dorsal view; E, same, ischium and merus, ventral view; F, same, carpus and chela, dorsal view (setae omitted); G, same, chela, ventral view.

FIGURE 7. Eumunida smithii Henderson, 1885, ovigerous female (cl 5.8 mm), JAMSTEC 105849. A, thoracic sternites 3 and 4, ventral view (setae on left side omitted); B, telson, outer view (setae omitted); C, right pereopod 2, lateral view (setae omitted); D, same, dactylus, lateral view; E, right pereopod 3, lateral view; F, right pereopod 4, lateral view.

FIGURE 8. A colony of an unidentified species of hydrocoral, on which specimens of E. smithii Henderson, 1885 were associated. Photo taken during KM-ROV dive#126, Shotoku Seamount, at a depth of 316.9 m.