Kaasichiton incubatus ( Sirenko, 2017 ) Sirenko, 2024

Sirenko, Boris I., 2024, A new genus and two new species of brooding chitons (Mollusca: Polyplacophora) from the North-Western Pacific, Zootaxa 5492 (4), pp. 505-529 : 513-514

Kaasichiton incubatus ( Sirenko, 2017) n. comb.

( Figures 6–8 )

Leptochiton sp. 1 ; Sirenko 2013: 148.

Leptochiton sp. ; Sirenko 2015: 29.

Leptochiton incubatus n. sp.; Sirenko 2017: 111, figs 1–3.

Type material. Holotype ( ZIN 2255 ), and paratype ( ZIN 2256 ),

Type locality. Type locality. North-western Pacific, near East Kamchatka Peninsula, 53°27.9′– 53°25.4′N, 160°20.0– 160°21.5′E, 1763–1815 m, pelite, mud and large pebbles .

Distribution. North-western Pacific, eastern Kamchatka, near Kronotskiy Bay, 684–1763 m

Material examined. Three specimens in total. R/ V Vityaz 20 th cruise, st. 3303, Kamchatka Peninsula, Kronotskiy Bay , 53°54.2′N, 160°42.7′E, 684 m, 1 spm, BL 6.0 mm, 24.05.1955 ; R/ V Akademik Keldysh, 22 nd cruise, st. 2328, North-western Pacific, near Kamchatka Peninsula, 53°27.9′– 53°25.4′N, 160°20.0′– 160°21.5′E, 1763–1815 m, pelite, mud and large pebbles, dredge, holotype ( ZIN 2255 ) , BL 6.5 mm and paratype ( ZIN 2256 ), BL 6.6 mm, 14.08.1990 .

Remarks. As mentioned in the description of this species ( Sirenko 2017), it appeared to bear eggs and juveniles in the pallial groove. The paratype (ZIN 2456) is a female (BL 6.6 mm) brooding 7 young chitons in the pallial grooves, five on the right side and two on the left side. The juveniles have 8 valves and are ready to leave leave pallial groove of the female individual. The young chitons have a body length of 1.1 mm, which is the largest size known among all brooding chiton species ( Sirenko 2015).

Figures

FIGURE 6. Kaasichiton incubatus, Eastern Kamchatka, near Kronotskiy Bay, 684 m, BL 6.0 mm: A. Valve I, dorsal view; B. Valve V, dorsal view; C. Valve VIII, dorsal view; D. Valve V, detail of tegmentum surface of central area; E. Valve V, rostral view; F. Valve VIII, lateral view.

FIGURE 7. Kaasichiton incubatus, Eastern Kamchatka, near Kronotskiy Bay, 684 m, BL 6.0 mm: A. Dorsal scales; B, C. Dorsal and ventral scales and marginal needles; D. Radula.

FIGURE 8. Kaasichiton incubatus, Eastern Kamchatka, near Kronotskiy Bay, 1763–1815 m, holotype (ZIN 2255), 6.5 mm: A. Sutural needle; B. Dorsal scales; C. Dorsal needle; D. Marginal needle; E. Ventral scale; F. Central and first lateral tooth of radula; G-J. heads of major lateral teeth, frontal view (G-I), lateral view (J); K. Granule with aesthete pore, diameter of granule about 50 µm. Scale bar: 100 μm (A-J). The drawing was taken from an article by Sirenko 2017, where it was poorly depicted.