Polybranchia samanthae, Medrano & Krug & Gosliner & Kumar & Valdés, 2019

POLYBRANCHIA SAMANTHAE View in CoL SP. NOV.

( FIGS 2, 3, 6D, 8C–D, 15, 16)

Type material

Holotype: Maui , Hawaiian Islands, 28 June 2016, 17-mm long, isolate MM034 ( LACM 3466 About LACM ).

Additional material examined

Guam, one specimen, isolate U003 . Saudi Arabia, Red Sea , 4 March 2013, one specimen, 20-mm long, isolate MM067 ( CASIZ 192424 ) . Moloa‘a Beach , Kaua‘i, Hawaiian Islands, 7 July 2016, one specimen, 9-mm long, isolate MM028 ( CPIC 01772 ) . Hekili Point , Maui, Hawaiian Islands, 13 June 2011, one specimen, 2-mm long, isolate Maui 01 ( CPIC 00291 ) .

Description

External morphology: Colour pale olive-green to tan or brown, with evenly distributed small white papillae on dorsum ( Fig. 15). Rhinophores translucent with white frosted dorsal tips and several white papillae evenly throughout. Snowy white pigment below eyespots extends towards snowy white pericardium. Cerata translucent, olive-green or dark tan in colour; dorso-medial surface with large green patch enclosed by dense white pigment ( Fig. 6D). White colour extends from distal tip and stops before ceratal base; diminishes before reaching white margin ( Fig. 6D). Two medial papillae, one large and one small, white, made inconspicuous by white dorso-medial surface on cerata. Peduncle depression lacks colour. Few white dots and many small, dark-brown spots on foot.

Internal morphology: In a 9-mm long specimen from Kaua‘i, Hawaiian Islands (CPIC 01772), radula with 28 teeth: six in ascending limb, six distinct teeth and 16 teeth encased in tissue in descending limb ( Fig. 16B). In a 2-mm long specimen from Maui, Hawaiian Islands (CPIC 00291), radula with 33 teeth: six in ascending limb, four distinct teeth and 23 teeth encased in tissue in descending limb ( Fig. 16C). Ascus lost in specimen CPIC 01772 ( Fig. 16B). Additional teeth encased in ascus in specimen CPIC 00291 ( Fig. 16E); number unknown. Leading tooth with two rows of 11 blunt denticles on basal surface in Kaua‘i specimen (CPIC 01772), larger near base and decrease in size toward hooked cusp ( Fig. 16A), and with two rows of 12 blunt denticles on basal surface in Maui specimen (CPIC 00291), also larger near base and decrease in size toward ‘hooked’ cusp ( Fig. 16D).

Penis long and smooth. Penis compressed from prostate sac to blunt tip, resembling a thin ribbon ( Fig. 8C–D). Penial stylet absent.