Typhlocarcinops kanashi, Ng & Rahayu, 2020

Ng, Peter K. L. & Rahayu, Dwi Listyo, 2020, A synopsis of Typhlocarcinops Rathbun, 1909 (Crustacea: Decapoda: Brachyura: Pilumnidae), with descriptions of nine new species from the Indo-West Pacific, Zootaxa 4788 (1), pp. 1-100 : 83-86

publication ID	https://doi.org/ 10.11646/zootaxa.4788.1.1
publication LSID	lsid:zoobank.org:pub:7A461DBA-00B7-48DB-9320-4775DA8F21B2
persistent identifier	https://treatment.plazi.org/id/03C05222-FFF0-FC59-FF35-D451FCC8FF1D
treatment provided by	Plazi
scientific name	Typhlocarcinops kanashi
status	sp. nov.

Treatment

Typhlocarcinops kanashi View in CoL n. sp.

( Figs. 70 View FIGURE 70 , 71 View FIGURE 71 )

Typhlocarcinops decrescens View in CoL — Sakai 1965: 171, pl. 84, fig. 5; text-fig. 22; 1976: 546, pl. 195, fig. 2; text-fig. 293 (not Typhlocarcinops decrescens Rathbun, 1914 View in CoL ).

Material examined. Holotype: male (3.9 × 3.0 mm) (NSMT-Cr 11575a), station 7, Onagawa Bay , Miyagi Prefecture, Japan, 36 m, coll. M. Takeda, 26 September 1994 . Paratypes: 1 male (3.7 × 2.9 mm) (NSMT-Cr 11575b), same data as holotype ; 1 male (4.5 × 3.5 mm) (NSMT-Cr 1212), Kagoshima, Japan, coll. 19 August 1975 .

Diagnosis. Carapace ( Fig. 70A, B, H View FIGURE 70 ) about 1.3 times broader than long, slightly narrowing on posterolateral margin, surface with tufts of short plumose setae, regions demarcated, H-shaped gastro-cardiac grooves shallow, indistinct, anterolateral margin arcuate, lined with small granules, separated by 2 broad, sharp teeth; posterolateral margin subparallel; posterolateral surface with scattered tubercles. Front bilobed ( Fig. 70B, C, H View FIGURE 70 ), with shallow median cleft, margin of each lobe convex. Orbit ( Fig. 70C View FIGURE 70 ) short, bulbous ocular peduncles filling orbit, immovable, cornea small, pigmented. Epistome ( Fig. 70C View FIGURE 70 ) relatively broad, triangular median lobe with slight median suture. Antennal peduncles long. Third maxilliped ( Fig. 71A View FIGURE 71 ) with merus broad, outer and inner margins straight, anteroexternal angle protruding, auriculiform, ischium as broad, but slightly longer than merus, inner margin subequal in length to outer margin; exopod broad, relatively stout. Chelipeds slightly unequal in males ( Fig. 70A, F View FIGURE 70 ), outer surface of dactylus and fixed finger with longitudinal ridge, sparse tubercles on proximal upper outer surface of dactylus; long fine setae on upper and lower margins of dactylus and fixed finger, cutting edges with prominent broad teeth; palm with large tubercles on outer lower and upper surface, carpus and merus smooth, tufts of sparse setae on its surfaces; inner angle of carpus with low tooth ( Fig. 70E View FIGURE 70 ). P2−P5 proportionally long ( Fig. 70A, G View FIGURE 70 ); proximal dorsal margin of the merus of first to third ambulatory legs with 1 or 2 small sharp granules; lateral surface, dorsal and ventral margins lined with long setae; dactylus straight, relatively short; merus of P5 not reaching front when folded. Fused thoracic sternites 1, 2 broadly triangular ( Fig. 70D View FIGURE 70 ), proportionally narrow; thoracic sternites 3, 4 fused, suture discernible. Male pleon ( Fig. 71B, E View FIGURE 71 ) relatively broad; telson relatively short, 1.4 times as long as somite 6, with rounded distal margin. G1 ( Fig. 71C, D View FIGURE 71 ) slender, curved, upper half longer than lower half, gently sinuous, distal part bent at almost right angles, tip tapering, with setae subdistally. Females not known.

Etymology. The name is derived from the classical Japanese word “kanashi, meaning pretty and beloved; alluding to the delicate features of the species. The name is used as a noun in apposition.

Remarks. Typhlocarcinops kanashi n. sp. is most similar to T. diminutus n. sp. but can be separated, with the anteroexternal angle of the merus of the third maxilliped strongly produced and the ischium is relatively short ( Fig. 71A View FIGURE 71 ) (versus anteroexternal angle gently produced with the ischium much longer in T. diminutus n. sp.; Fig. 69A View FIGURE 69 ); the proximal dorsal margin of the merus of the ambulatory leg has one or two small sharp granules ( Fig. 70G View FIGURE 70 ) (versus dorsal margin of merus entire in T. diminutus n. sp.; Fig. 67H View FIGURE 67 ); the ambulatory dactylus is proportionately shorter ( Fig. 70G View FIGURE 70 ) (versus ambulatory dactyus proportionately longer in T. diminutus n. sp.; Fig. 67H View FIGURE 67 ); male pleonal somites 4–6 are proportionately broader ( Fig. 71B View FIGURE 71 ) (versus pleonal somites proportionately more narrow in T. diminutus n. sp.; Fig. 69B View FIGURE 69 ); and G1 is gently sinuous with the distal part bent at almost right angles ( Fig. 71C, D View FIGURE 71 ) (versus G1 strongly sinuous with the distal part more prominently curved in T. diminutus n. sp.; Fig. 69C, D View FIGURE 69 ).

Sakai (1965) reported this species as “ T. decrescens ” based on a Sagami Bay male measuring 8.0 × 6.2 mm and later reported a second specimen from Manazuru, also in Japan ( Sakai 1976). The carapace as figured by him has three low lobes along the anterolateral margin ( Sakai 1965: text-fig. 22a; 1976: text-fig. 293a), and in this aspect, superficially resembles the condition in T. canaliculatus , T. decrescens and T. denticarpes . The shape of the male pleon ( Sakai 1965: text-fig. 22c) and especially the structure of the third maxilliped ( Sakai 1965: text-fig. 22d), with the distinctive short ischium and prominently auriculiform anteroexternal angle indicate otherwise. His specimens are here identified as T. kanashi n. sp. (cf. Fig. 71A View FIGURE 71 ) instead. The anterolateral margin of the types of T. kanashi n. sp. are relatively sharper and more dentate ( Fig. 70B, H View FIGURE 70 ) but they are still low and the condition figured by Sakai (1965, 1976) may be due its proportionately larger carapace size. The G1 as figured by Sakai (1965: text-fig. 22b; 1976: text-fig. 293b) agree well with what is figured for T. kanashi n. sp. ( Fig. 71C, D View FIGURE 71 ).