Leucothoe bise, White, Kristine N. & Reimer, James Davis, 2012

White, Kristine N. & Reimer, James Davis, 2012, Commensal Leucothoidae (Crustacea, Amphipoda) of the Ryukyu Archipelago, Japan. Part II: sponge-dwellers, ZooKeys 166, pp. 1-58 : 5-8

Leucothoe bise sp. n. Figures 34

Type material.

Holotype male, 2.1 mm RUMF-ZC-1738, Bise, Okinawa–jima Island, Okinawa, reef wall (26°42'46"N, 127°52'44"E), among coral rubble, 7-15 m, K.N. White and N.S. White, col., 9 February 2011 (KNWOkinawa30D). Paratype female, 3.6 mm RUMF-ZC-1739, same station data as holotype. Paratype male, 3.3 mm RUMF-ZC-1846, Yona, Kunigami, Okinawa–jima Island, Okinawa, reef wall (26°45'56"N, 128°46'39"E), among coral rubble, 9 m, K.N. White and N.S. White, col., 23 October 2010 (KNWOkinawa15E).

Type locality.

Bise, Okinawa–jima Island, Okinawa, Japan (26°42'46"N, 127°52'44"E).

Additional material examined.

1 specimen, NSMT-Cr 21875, KNWOkinawa23F; 1 specimen, NSMT-Cr 21876, KNWOkinawa27E; 1 specimen, RUMF-ZC-1740, KNWOkinawa29B; 1 specimen, RUMF-ZC-1741, KNWOkinawa29M; 6 specimens, RUMF-ZC-1742, KNWOkinawa30D; 1 specimen, NSMT-Cr 21877, KNWOkinawa31G; 5 specimens, NSMT-Cr 21878, KNWOkinawa39I; 6 specimens, NSMT-Cr 21879, KNWOkinawa43C; 1 specimen, NSMT-Cr 21880, KNWOkinawa50C; 1 specimen, RUMF-ZC-1743, KNWOkinawa55A; 5 specimens, RUMF-ZC-1795, KNWYaku3G; 1 specimen, RUMF-ZC-1847, KNWOkinawa15E; 1 specimen, RUMF-ZC-1848, KNWOkinawa15E; 4 specimens, NSMT-Cr 21991, KNWOkinawa15E; 1 specimen, RUMF-ZC-1849, KNWOkinawa21C; 2 specimens, NSMT-Cr 21992, KNWOkinawa13E.

Diagnosis (male).

Head anterodistal margin quadrate with cusp. Antenna 1 with many setulate-serrate setae. Maxilla 1 palp 1-articulate, margins constricted. Gnathopod 1 basis proximally widened; propodus palm serrate, saw-like. Gnathopod 2 carpus distally rounded; propodus with 2 mediofacial setal rows, primary mediofacial setal row very short. Pereopods 5-7 bases very narrowly expanded. Female gnathopod 1 basis posterior margin with 7 setae; gnathopod 2 carpus distally truncate.

Description (male).

Head. Anterior margin truncate, anterodistal margin quadrate with cusp; ventral cephalic keel anterior margin transverse, anteroventral margin quadrate, ventral margin straight; eyes with more than 10 ommatidia, round. Antenna 1 0.3 × body length, with setulate-serrate setae, flagellum 4-articulate, peduncle article 1 width less than 2 × article 2, accessory flagellum absent. Antenna 2 0.3 × body length, subequal in length with antenna 1, flagellum 3-articulate. Mandibular palp ratio of articles 1-3 1.0: 3.0: 1.8, article 2 with 5 medium distal setae, article 3 with 2 distal setae, incisors strongly dentate; left mandible lacinia mobilis with 12 raker spines, large, strongly toothed; right mandible with 10 raker spines, lacinia mobilis small, strongly dentate. Upper lip asymmetrically lobate, anterior margin setose. Lower lip inner lobes fused, bare; outer lobes with moderate gape, anterior margins setose. Maxilla 1 palp 1-articulate, margins constricted and with 4 distal setae; outer plate with 5 distal robust setae and 4 distal setae. Maxilla 2 inner plate with 5 robust distal setae; outer plate with 3 robust distal setae and 11 slender distal marginal setae. Maxilliped inner plates distal margin with a v-shaped indentation, with short robust setae; outer plate inner margin smooth, reaching 0.2 × palp article 1, with simple marginal setae, facial setae absent; palp 4-articulate, article 4 subequal in length with article 3, distally acute.

Pereon. Coxae 1-4 relative widths 1.0: 1.0: 0.9: 1.1. Gnathopod 1 coxa smooth, with tiny marginal setae, anterodistal margin produced, subtriangular, distal margin straight, posterior margin excavate, facial setae absent; basis proximally widened, anterior margin bare, posterior margin with 2 setae; ischium bare; carpus linear, distal length 18.8 × width, proximal margin smooth, distal margin bare; propodus straight, palm serrate, saw-like, with 3 robust and 5 short proximal setae; dactylus smooth, reaching 0.4 × propodus length. Gnathopod 2 coxa broader than long, subequal in size to coxa 3, smooth, with tiny marginal setae, anterior margin straight, anterodistally acute, distal and posterior margins straight, facial setae absent; basis linear, anterior margin with 3 setae, posterior margin bare; ischium bare; carpus 0.3 × propodus length, curved, distally rounded, anterior margin smooth; propodus with 2 mediofacial setal rows, primary mediofacial setal row above midline, reaching 0.4 × propodus length, secondary mediofacial setal row with 1 seta, with 1 row of submarginal setae, posterior margin smooth, palm convex, dentate; dactylus curved, proximal margin smooth, with 2 setae, anterior margin distally subacute, reaching 0.6 × propodus length. Pereopod 3 coxa length 0.9 × width, anterodistal corner overriding distal face of coxa 2 and extending below it, smooth, with tiny marginal setae, anterior margin evenly rounded, distal margin slightly convex, posterior margin straight, facial setae absent. Pereopod 4 coxa smooth, with tiny marginal setae, anterior margin tapered, distal margin straight, posterior margin tapered, facial setae absent. Pereopods 5-7 coxae facial setae absent; bases width length ratios 1: 1.9, 1: 1.7, 1: 1.8, posterior margins smooth, setose.

Pleon. Epimera 1 and 3 bare, epimeron 2 with ventral setae; epimeron 3 posteroventral corner subquadrate, produced. Uropods 1-2 relative lengths 1.0: 0.9; inner and outer rami lined with short marginal setae. Uropod 1 peduncle 0.9 × inner ramus length, outer ramus subequal in length with inner ramus length; inner ramus with 2 robust setae, outer ramus with 1 robust seta. Uropod 2 peduncle 0.7 × inner ramus length, outer ramus 0.9 × inner ramus length; inner ramus with 1 robust seta, outer ramus with 2 robust setae. Uropod 3 missing. Telson 2.1 × longer than wide, with plumose facial setae, apex weakly tridentate.

Female (sexually dimorphic characters).

Gnathopod 1 basis anterior margin with 1 seta, posterior margin with 7 setae; ischium with 2 posterior setae; carpus distal margin with 3 setae. Gnathopod 2 basis anterior margin with 10 medium setae, posteromedial margin with 1 seta; carpus distally truncate, reaching 0.5 × propodus length; propodus secondary mediofacial setal row with 4 setae, palm with more prominent tubercles.

Etymology.

After the Japanese place name, ‘Bise’, and referring to the type locality. (Pronounced bee-say.)

Ecology.

In canals of sponges, Tedania of Gray 1867 (Figure 25E); and among coral rubble.

Relationships.

Leucothoe bise sp. n. is similar to Leucothoe hortapugai Winfield et al., 2009 and Leucothoe kensleyi Thomas & Klebba, 2006 in having a quadrate anterior head margin, anterodistal head margin quadrate with cusp, narrow pereopod 5-7 bases, and gnathopod 1 dactylus reaching less than 0.2 × propodus. It differs from these species in having a quadrate keel without a projection, maxilla 1 palp 1-articulate, margins constricted, bare gnathopod 1 basis anterior margin, gnathopod 2 carpus distally rounded and reaching less than 0.4 × propodus length, and a produced posteroventral margin on epimeron 3.

Remarks.

Some sexually dimorphic characters may be due to the larger size of the female. Some specimens have larger serrations on the saw-like gnathopod 1 propodus palm, suggesting morphological variation in this character, perhaps depending on size. Leucothoe bise sp. n. is translucent orange in color (Figure 24B). This species has been collected on Iriomote–jima and throughout the western coast of Okinawa–jima Island, Okinawa.

Distribution.

East China Sea: Okinawa–jima Island, Iriomote–jima Island (both Okinawa), Japan.