Lobatoradarea anko Ariyama & Hoshino, 2025

Lobatoradarea anko Ariyama & Hoshino , sp. nov.

[New Japanese name: Anko-udenaga-yokoebi]

( Figs 12–16)

Type material. Holotype: ovigerous female, 5.5 mm (OMNH-Ar-13217), Akinohama Beach, Izu Ōshima Island , Tokyo, 34°47'14"N, 139°24'31"E ( Fig. 1D), 15–20 m depth, accumulated red algae, using SCUBA diving, 13 March 2025, coll. Osamu Hoshino. GoogleMaps Paratypes: female, 3.7 mm (OMNH-Ar-13218) and 2 males, 4.0, 3.9 mm (OMNH- Ar-13219, 13220), same data as holotype GoogleMaps ; female 5.0 mm (OMNH-Ar-13221), 24 March 2025, other data same as holotype GoogleMaps .

Type locality. Akinohama , Izu Ōshima Island in Tokyo, Japan .

Etymology. Anko refers to the women of Izu Ōshima Island wearing traditional kimonos. This word was made famous by a popular Japanese song by Harumi Miyako titled “ Anko-tsubaki-wa-koinohana ” (1964). Used as noun in apposition.

Description of female. Based on holotype, ovigerous female, 5.5 mm (OMNH-Ar-13217) and paratype, female, 5.0 mm (OMNH-Ar-13221) only for gnathopod 2 and epimeral plates.

Head ( Figs 12, 13). Rostrum well developed, lateral cephalic lobe rounded, anteroventral corner slightly projected. Eyes small (diameter: 25% of head height). Antenna 1 very long; peduncular articles 1–3 with length ratio of 1.0: 0.6: 0.2; accessory flagellum very short, bullet-shaped, with 1 long and 4 short setae; primary flagellum with 57 articles, article 1 relatively long, 2 articles with aesthetasc. Antenna 2, peduncular articles 3, 4 with length ratio of 1.0: 2.2, each article bearing several robust setae; peduncular article 5 and flagellum lost. Upper lip weakly produced ventrally, anterior surface and ventral margin bearing many minute setae. Mandibles, incisors with 9 and 8 cusps in left and right, respectively, laciniae mobilis 9- and 3-toothed in left and right, respectively, left accessory setal row with 5 thick and 5 slender setae, right accessory setal row bearing 4 thick and 1 slender setae; palp stout, article length ratio 1.0: 3.4: 2.2 in left, article 1 short, bare, article 2 long, with 3 setae subdistally, article 3 bearing 1 proximal, 10 ventral and 1 thick and 3 slender distal setae, lateral surface covered with dense thin setae. Lower lip, inner lobes developed, bare; outer lobes with relatively long mandibular lobes minutely setose proximally, distal parts of outer lobes with many slender and fine setae, middle parts bearing sparse fine setae ventrally and laterally. Maxilla 1, inner plate pear-shaped, medial margin bearing long plumose setae, tip with 1 long and 4 short setae; outer plate distally with 11 denticulate robust setae, mediodistal margin bearing 6 thick and many slender setae; palp article 1 bare, article 2 apically with 7 triangular and 1 long robust setae and 4 slender setae in left and 9 narrow robust setae and 6 slender setae in right. Maxilla 2, inner plate ca. 1.4 times width of outer plate. Maxilliped, inner plate with 3 triangular robust setae distally; outer plate bearing 5 long and 12 short robust setae mediodistally; palp article 3 dorsal surface with 5 thick setae and many fine setae.

Pereon ( Figs 12, 14). Pereonite 7 not projected posterodorsally. Gnathopod 1 short; coxa roundish, with a small notch each on anteroventral and posteroventral margins, medial surface bearing several setae; basis slender, straight, anterior margin lined with robust setae, posterior margin and lateral surface bearing 3 and 2 long setae, respectively, medial surface with 7 long setae; merus acutely projected distally, with several thick setae on posterodistal margin, posterolateral surface minutely setose in middle; carpus relatively long, posterior margin bearing many thick setae; propodus slightly shorter than carpus (ca. 0.95 times), posterior margin with many thick setae, palm weakly oblique, defined by 2 (1 lateral and 1 medial) short robust setae; dactylus short. Gnathopod 2 much longer than gnathopod 1; coxa roundish rectangular, with a small notch each on anteroventral and posteroventral margins, medial surface bearing 4 setae; basis slender, straight, anterior margin with 3 robust setae and 6 slender setae, posterior margin and lateral surface bearing 6 and 2 long setae, respectively; merus acutely projected distally, posterior margin with a few setae; carpus long and narrow, posterior margin bearing several bundles of slender setae; propodus longer than carpus (ca. 1.3 times), narrow, anterior margin lined with slender setae, posterior margin bearing many bundles of slender setae, palm weakly oblique, defined by 2 (1 lateral and 1 medial) short robust setae; dactylus short. Pereopod 3, coxa roundish rectangular, with a small notch each on anteroventral and posteroventral margins, medial surface without setae; basis slightly curved anteriorly, anterior margin and anterodistal corner with 3 and 2 robust setae, respectively, posteroproximal margin with a few slender setae, posterior margin and posterodistal corner bearing 2 and 1 robust setae, respectively; merus anterodistal corner with 1 long and 1 short robust setae; carpus–dactylus lost. Pereopod 4, coxa ventral margin rounded, with 1 and 3 small notches on anteroventral and posteroventral margins, respectively, medial surface bare; basis–merus similar to those of pereopod 3. Pereopod 5, coxa anteroventral and posterior margins with 2 and 4 small notches, respectively; basis ovoid, with anterolateral ridge, anterior margin with a few proximal seta and 4 short robust setae, anterodistal corner bearing a robust seta, posterior margin minutely serrated, medial surface with vertical ridge bearing a robust seta; ischium with a robust seta at anterodistal corner; merus with 2+2+1 anterior, 4 anterodistal, 2 posterior and 3 posterodistal robust setae; carpus with 1+2+2 anterior, 3 anterodistal, 2 posterior and 2 posterodistal robust setae; propodus with 1+2+2+2 anterior, 4 anterodistal and 2+2+2 posterior robust setae; dactylus with a minute projection. Pereopod 6 about 1.2 times as long as pereopod 5; coxa anterior margin straight, with a seta, posteroventral margin with 5 small notches; basis ovoid, with anterolateral ridge, anterior margin with several proximal setae and 4 robust setae, anterodistal corner bearing a robust seta, posterior margin minutely serrated, medial surface with vertical ridge bearing a robust seta; ischium with a robust seta at anterodistal corner; merus with 2+2+2 anterior, 3 anterodistal, 3 posterior and 5 posterodistal robust setae; carpus with 2+2+2 anterior, 5 anterodistal, 2+2 posterior and 5 posterodistal robust setae; propodus with 2+2+2+2+2 anterior, 2 anterodistal and 2+2+2 posterior robust setae; dactylus with a minute projection. Pereopod 7 about 1.1 times as long as pereopod 6; coxa short, oval, posteroventral margin with 3 small notches; basis ovoid, with anterolateral ridge, anterior margin with several proximal setae and 5 robust setae, anterodistal corner bearing a robust seta, posterior margin minutely serrated, medial surface with short vertical ridge bearing a robust seta; ischium with a thick seta at anterodistal corner; merus with 2+2+3 anterior, 3 anterodistal, 3 posterior and 4 posterodistal robust setae; carpus with 2+2+2+3 anterior, 5 anterodistal, 2+2+2 posterior and 4 posterodistal robust setae; propodus with 2+2+2+2+2+2 anterior, 2 anterodistal and 2+2+2+3 posterior robust setae; dactylus with a minute projection.

Pleon ( Figs 12, 15). Pleonites 1, 2 projected posterodorsally. Epimeral plates 1–3, posteroventral corners minutely produced, lateral surfaces in plates 1, 2 with ridge, ventral margins in plates 2, 3 each bearing 2 robust setae. Pleopods, pleopod 2 longest; each peduncle bearing a few short setae and 2 coupling hooks, peduncles of pleopods 1–3 with 3, 2 and 5 posteromedial robust setae, respectively, peduncle of pleopod 3 also bearing a lateral robust seta; both rami almost same length, with 13–15 articles. Uropod 1, peduncle long, dorsal surface with 6 lateral, 1 laterodistal, 4 medial and 1 mediodistal robust setae, ventrodistal end slightly produced; outer ramus ca. 0.6 times length of peduncle, with 3 lateral and 3 terminal robust setae; inner ramus ca.1.65 times as long as outer ramus, with 4 lateral, 4 medial and 4 terminal robust setae. Uropod 2 about 0.9 times as long as uropod 1; peduncle short, with 3 lateral, 1 laterodistal and 1 mediodistal robust setae, ventrodistal end slightly produced; outer ramus ca. 0.8 times length of peduncle, with 3 lateral and 3 terminal robust setae; inner ramus about ca. 2.2 times as long as outer ramus, with 6 lateral, 6 medial and 4 terminal robust setae. Uropod 3 about 0.85 times length of uropod 2; peduncle very short, longer than wide, ventrodistal end triangularly produced, ventral margin with 4 short setae; outer ramus ca. 1.85 times length of peduncle, with 5 lateral and 3 medial robust setae; inner ramus about 1.6 times as long as outer ramus, with 8 lateral and 10 medial robust setae. Telson small, trapezoidal, distal margin truncated, with a small notch in right side, dorsal surface bearing 6 sensory setae, margins with 9 minute setae.

Description of male. Based on paratype, male, 4.0 mm (OMNH-Ar-13219) and paratype, male, 3.9 mm (OMNH-Ar-13220).Almost similar to holotype, ovigerous female, 5.5 mm (OMNH-Ar-13217) except for oostegites. Gnathopods resembling those of female; but medial surfaces of coxae and bases less setose ( Fig. 15M 1 -RC1, M2- RG1 and M2-RG2).

Coloration in life. Based on paratype, female, 5.0 mm (OMNH-Ar-13221, Fig. 16). Head white, eyes bright red; pereonite 1 white with dark red anterior and posterior margins, pereonite 2–6 white with dark red posterior margins, pereonite 7 and pleonites 1, 2 white with dark red dorsal band (faint in pleonite 2) and dark red posterolateral point, pleonite 3 and urosomites 1–3 white; antennae white with pale red distal margin of peduncular articles; coxae white with dark red anterior or posterior margin, basis of pereopod 5 mostly dark red, other parts of pereopods, pleopods and uropods white or faintly pink.

Remarks. Only two species have small eyes in Lobatoradarea gen. nov.: L. anko sp. nov. and L. littoralis sp. nov. This new species can be distinguished from L. littoralis by the minutely produced posteroventral corner of the epimeral plate 2 (that of L. littoralis is strongly produced).

Habitat. Among algae in the shallow subtidal zone ( 15–20 m depth).

Distribution. Japan: Izu Ōshima Island in Tokyo (present study).