Paraleptochelia setosa, Tzeng & Hsueh, 2021

Tzeng, You-Wei & Hsueh, Pan-Wen, 2021, Additions of new species to the Paratanaoidea (Crustacea, Tanaidacea) of Taiwan, Zootaxa 4949 (1), pp. 131-148 : 133-136

Paraleptochelia setosa sp. nov.

Figs 1–5

Material examined. Holotype: non-ovigerous female ( NMNS 8288-01 ), body length 2.5 mm, Jihuei (23°06’54.9”N, 121°24’16.3”E), Taitung County, eastern Taiwan, intertidal, washing from polychaetous worm tube of Eunice taoi Hsueh & Li, 2014 , collected by You-Wei Tzeng, 22 July 2013.

Allotype: male ( NMNS 8288-02 ), body length 2.1 mm, Shitiping (23°28’57.4”N, 121°30’46.9”E), Hualien County, eastern Taiwan, intertidal, washing from red alga Amansia glomerata C. Agardh, 1822 , collected by You-Wei Tzeng, 17 August 2011.

Paratypes:male ( NMNS 8288-03 ), body length 2.2 mm, same collection data as allotype ; male ( NMNS 8288-04 ), body length 2.2 mm, Jialulan (22°48’10.2”N, 121°11’57.0”E), Taitung County, eastern Taiwan, intertidal, from sand pile, collected by You-Wei Tzeng, 23 July 2013 ; male ( NMNS 8288-05 ), Shitiping (23°28’57.4”N, 121°30’46.9”E), Hualien County, eastern Taiwan, intertidal, collected by You-Wei Tzeng, 17 August 2011 ; male ( NMNS 8288-06 ), body length 2.1 mm, Shitiping (23°28’57.4”N, 121°30’46.9”E), Hualien County, eastern Taiwan, intertidal, washing from red alga Mastophora rosea (C. Agardh) Setchell, 1943 , collected by You-Wei Tzeng, 20 August 2012 ; non-ovigerous female ( NMNS 8288-07 ), body length 2.4 mm, same collection data as holotype ; 3 non-ovigerous females ( NMNS 8288-08 ), same collection data as allotype ; male ( NMNS 8288-09 ), Jihuei (23°06’54.9”N, 121°24’16.3”E), Taitung County, eastern Taiwan, intertidal, washing from M. rosea , collected by You-Wei Tzeng, 18 April 2012 ; male ( NMNS 8288-10 ), Jihuei (23°06’54.9”N, 121°24’16.3”E), Taitung County, eastern Taiwan, intertidal, washing from polychaetous worm tube of E. taoi , collected by You-Wei Tzeng, 18 April 2012 ; non-ovigerous female ( NMNS 8288-11 ), same collection data as NMNS 8288-10 ; male ( NMNS 8288-12 ), same collection data as NMNS 8288-10 ; 3 non-ovigerous females ( NMNS 8288-13 ), same collection data as NMNS 8288-10 ; male ( NMNS 8288-14 ), Shitiping (23°28’57.4”N, 121°30’46.9”E), Hualien County, eastern Taiwan, intertidal, washing from red alga M. rosea , collected by You-Wei Tzeng, 21 April 2012 ; 8 non-ovigerous females ( NMNS 8288-15 ), same collection data as holotype ; 4 males ( NMNS 8288-16 ), same collection data as holotype ; 3 non-ovigerous females ( NMNS 8288-17 ), Shitiping (23°28’57.4”N, 121°30’46.9”E), Hualien County, eastern Taiwan, intertidal, washing from red alga A. glomerata , collected by You-Wei Tzeng, 21 April 2012 .

Diagnosis. Female: Body about 7.5 times longer than wide. Maxilliped endite distal margin with one long and strong seta and two blunt spines, inner margin with two coupling hooks. Pereopods 4–6 carpus with four distal spines. Pereopod-6 ischium with two ventral setae. Uropod exopod two-articled, endopod five-articled. Male: Body about six times longer than wide. Carapace 1.5 times longer than wide. Antennule flagellum five-articled, article- 1 with a cluster of proximal aesthetascs and distal aesthetascs. Antenna article-2 without ventral spine. Cheliped carpus about six times longer than wide, fixed finger incisive margin with one low and blunt middle apophysis, and one smaller apophysis on distal one-thirds. Uropod peduncle with a pair of long inner-distal setae and a pair of long ventral setae; exopod two-articled, endopod five-articled.

Description (some characters stated in generic or species diagnosis not included). Female: Habitus ( Fig. 1A ) body slender dorsoventrally flattened. Carapace long elliptical, 0.2 times as long as body, lateral margins with three setae. Pereon 0.6 times as long as body; pereonite-1 shortest, 0.3 times as long as carapace, 0.5 times as long as wide; pereonite-2 about 1.4 times longer than pereonite-1, 0.7 times as long as wide; pereonite-3 1.1 times longer than pereonite-2, 0.8 times as long as wide; pereonite-4 longest, 1.3 times longer than pereonite-3, slightly longer than wide; pereonite-5 0.9 times as long as pereonite-4, nearly as long as wide; pereonite-6 0.8 times as long as pereonite-5, 0.8 times as long as wide; all pereonites with one anterolateral seta. Pleon about 0.2 times as long as body; all pleonites about the same length, with two setae on lateral margin. Pleotelson with two pairs of setae on distal margin.

Antennule ( Fig. 1C ) three-articled plus one distal cap-like segment, 0.6 times as long as carapace; article-1 longest, 0.6 times as long as total length and about 2.7 times longer than wide, outer and inner margin with one subdistal seta, distal margin with one long seta and three broom setae; article-2 about 0.3 times as long as article-1, with two distal setae; article-3 almost 1.2 times longer than article-2, distal margin with two setae, one broom seta, and one aesthetasc; cap-like segment with four long setae.

Antenna ( Fig. 1D ) six-articled; article-1 short and naked; article-2 distal margin with one strong dorsal spine and one strong ventral spine; article-3 shorter than article-2, distal margin with one strong dorsal spine; article-4 longest, over 0.3 times as long as total length, with two distal setae and one distal broom seta; article-5 about 0.6 times as long as article-4, with one distal seta; article-6 very short, with four distal setae.

Labrum not observed. Left mandible ( Fig. 1E ) lacinia mobilis large, subtriangular, distal margin crenulate; incisor with blunt acuminate apex, distal margin with one small protrusion; molar not observed. Right mandible ( Fig. 1F ) incisor with bifid apex and crenulate distal margin; molar robust, with distal ridges. Labium not observed. Maxillule ( Fig. 1G ) palp with two distal setae; endite with eleven distal spines, outer margin covered with setules, inner margin with five short setae. Maxilla and epignath not observed. Maxilliped ( Fig. 2A ) endite ( Fig. 2B ) distal margin covered with setules; palp article-1 naked, article-2 outer margin with one distal seta, inner margin with one distal seta and three subdistal setae, article-3 inner margin with six setae, article-4 outer margin with one seta, distal margin with six setae.

Cheliped ( Fig. 2C ) basis 0.4 times as long as total length, 1.6 times longer than wide, with one lateral seta; merus triangular; carpus robust, 0.5 times as long as total length, 2.1 times longer than wide, dorsal margin with one distal seta and two small spinules on proximal half, ventral margin with three setae; propodus stout, palm about 1.5 times longer than wide, with one seta and a comb-like row of three setae near dactylus articulation, fixed finger thick, 1.5 times longer than wide, incisive margin with three low process, unguis small; dactylus curved, outer margin with one small proximal seta, incisive margin with one medial low process, unguis larger than that of fixed finger.

Pereopod-1 ( Fig. 2D ) long and slender; coxa with one seta; basis curved, four times longer than wide, dorsal margin with one dorso-subproximal short seta; merus less than 0.4 times as long as basis, naked; carpus nearly as long as merus, with one long and one short dorsodistal seta; propodus about 0.7 times as long as basis, dorsal margin with a cluster of four subdistal setae and one small subdistal spinule, ventral margin with one subdistal seta; dactylus plus unguis curved, almost as long as propodus, unguis 1.3 times longer than dactylus. Pereopod-2 ( Fig. 2E ) shorter than pereopod-1; coxa with one seta; basis dorsal margin with one short seta on proximal half; merus 1.5 times longer than wide; carpus as long as merus; propodus almost two times longer than carpus, dorsal margin with two long subdistal setae and one small subdistal spinule, ventral margin with one subdistal seta; dactylus curved, with unguis.

Pereopod-3 ( Fig. 2F ) very similar to pereopod-2 but propodus dorsal margin with only one subdistal seta.

Pereopod-4 ( Fig. 3A ) coxa with one seta; basis thick, 2.1 longer than wide, with two ventral broom setae; merus about 0.6 times as long as basis, two times longer than wide; carpus slightly shorter than merus, 1.7 times longer than wide, with one dorsodistal seta, with four spines on distal extremity; propodus 1.3 times longer than carpus, 2.5 times longer than wide, dorsal margin with one distal bipinnate seta, two subdistal setae and one small subdistal spinule, ventral margin with two subdistal spines; dactylus curved, with short unguis. Pereopod-5 ( Fig. 3B ) very similar to pereopod-4 but basis with only one ventral broom seta, carpus without dorsal seta.

Pereopod-6 ( Fig. 3C ) coxa with one seta; basis over three times longer than wide, naked; merus about 0.4 times as long as basis, two times longer than wide, with one ventrodistal seta and two ventrodistal spines; carpus about as long as merus, two times longer than wide, with one dorsodistal seta, with four spines on distal extremity; propodus 1.3 times longer than carpus, 2.5 times longer than wide, dorsal margin with one distal seta, a cluster of three distal setae and one small subdistal spinule, ventral margin with two subdistal spines; dactylus curved, unguis short.

Pleopod-1 ( Fig. 3D ) peduncle naked; exopod outer margin with one circumplumose seta, distal to inner margin with ten plumose setae and one proximal circumplumose seta; endopod distal to inner margin with nine plumose setae and one proximal circumplumose seta.

Uropod ( Fig. 3E ) exopod article-1 with one distal seta, article-2 with two distal setae; endopod article-1 with one short distal seta and two distal broom setae, article-2 with two distal setae, article-3 longest, with one distal seta and one distal broom seta, article-4 with one distal seta, article-5 with two distal broom setae, one short and three long distal setae.

Male: Habitus ( Fig. 1B , figure and description based on NMNS 8288-06, 2.1 mm) slender, dorsoventrally flattened. Carapace oblong, less than 0.3 times as long as body, proximal half slightly wider than distal half, with three lateral setae, eye lobe distinct. Pereon over 0.5 times as long as body; pereonite-1 shortest but widest, about 0.3 times as long as wide; pereonite-2 slightly longer than pereonite-1, 0.5 times as long as wide; pereonite-3 1.3 times longer than pereonite-2, less than 0.7 times as long as wide; pereonite-4 1.4 times longer than pereonite-3, 0.9 times as long as wide; pereonite-5 slightly shorter than pereonite-4, 0.9 times as long as wide; pereonite-6 0.7 times as long as pereonite-5, 0.5 times as long as wide; all pereonites with one lateral seta. Pleon shorter than carapace, less than 0.2 times as long as body; all pleonites about the same length, with two lateral setae. Pleotelson with two distal setae.

Antennule ( Fig. 4A ) long, almost 0.6 times as long as body; peduncle article-1 long and slender, over 0.5 times as long as total length, 14 times longer than wide, with one distal seta and two distal broom setae; peduncle article-2 0.4 times as long as article-1, with one distal seta and one subdistal seta; peduncle article-3 very short, 0.2 times as long as article-2, with one distal seta; flagellum article-1 with a cluster of five proximal aesthetascs and two distal aesthetascs, articles 2 and 3 with three distal aesthetascs, article-4 with four distal aesthetascs, article-5 very small, with four setae.

Antenna ( Fig. 4B , figure and description based on NMNS 8288-03, 2.2 mm) article-1 naked; articles 2 and 3 short and thick, with one long dorsodistal spine; article-4 longest, about 0.35 times as long as total length, with two distal setae and four distal broom setae; article-5 0.5 times as long as article-4, with one distal seta; article-6 very short, with two long and one short seta.

Cheliped ( Fig. 4C ) basis short, 0.1 times as long as total length, 1.8 times longer than wide; merus short, 0.4 times as long as basis, with two ventral setae; carpus long and slender, 0.4 times as long as total length, with two dorsal and two ventral setae; propodus palm over six times longer than wide, with one seta near dactylus articulation, inner surface with a comb-like row of eleven setae; fixed finger partially curved, about 0.3 times as long as propodus, incisive margin with one low and blunt middle apophysis, one smaller distal apophysis and three setae on distal one thirds, outer margin with two setae, unguis short; dactylus ( Fig. 4D ) curved, with six spinules along incisive margin, proximal half of incisive margin with a row of teeth, within which the most proximal three (arrowed) especially larger, outer margin with one proximal seta, unguis short.

Pereopod-1 ( Fig. 4F ) merus 1.8 times longer than wide; carpus slightly longer and narrower than merus, 2.6 times longer than wide, dorsal margin with one subdistal seta; propodus 1.6 times longer than carpus, four times longer than wide, dorsal margin with two subdistal setae and one small distal spinule, ventral margin with one strong subdistal spine; dactylus plus unguis long and slightly curved, 0.8 times as long as propodus, with three small proximal spinules, unguis shorter than dactylus.

Pereopod-2 ( Fig. 4G ) basis five times longer than wide, dorsal margin with one seta and one broom seta on proximal half; merus less than 0.3 times as long as basis, 1.8 times longer than wide, with one ventrodistal spine; carpus slightly longer than merus, 1.6 times longer than wide, with one ventrodistal spine; propodus 1.7 times longer than carpus, three times longer than wide; dactylus curved, with one proximal transversal row of setules and one middle seta.

Pereopod-3 ( Fig. 5A ) very similar to pereopod-2 but propodus dorsal margin with one subdistal seta.

Pereopod-4 ( Fig. 5B ) coxa with one seta; basis not swollen, 2.7 times longer than wide, with one dorsal broom seta; ischium with two ventral seta; merus 0.4 times as long as basis, 1.8 times longer than wide, with two ventrodistal spines; carpus about as wide and as long as merus, distal margin with two setae and four spines; propodus 1.5 times longer than carpus, 3.3 times longer than wide, dorsal margin with three subdistal setae and one small subdistal spinule, ventral margin with two strong subdistal spines; dactylus curved, with distal setules, unguis sharp.

Pereopod-5 ( Fig. 5C ) very similar to pereopod-4.

Pereopod-6 ( Fig. 5D ) very similar to pereopods 4 and 5 but slightly longer, basis longer and thinner, almost four times longer than wide, with one long ventral seta, propodus slightly curved.

Pleopod-1 ( Fig. 5E , figure and description based on NMNS 8288-03) peduncle naked; exopod outer margin with one proximal short circumplumose seta, outer to distal margin with twelve plumose setae; endopod outer margin with one proximal short circumplumose seta, outer to distal margin with ten plumose setae, inner margin with one medial circumplumose seta.

Uropod ( Fig. 5F ) peduncle robust, distal margin with a pair of inner setae and a pair of long ventral setae; exopod two-articled, article-1 with one long distal seta, article-2 with two very long distal setae; endopod five-articled, article-1 and 2 distal margin with one seta and a pair of inner pear-shaped spines, article-3 longest, with two distal setae and two broom setae, article-4 with one distal seta, article-5 with two very long distal setae, two shorter distal setae and one distal broom seta.

Variation. Almost all males have a low and blunt middle apophysis on incisive margin of fixed finger of cheliped. However, two male paratypes (NMNS 8288-04 and NMNS 8288-05) have a subtriangular middle denticle on incisive margin of fixed finger of cheliped ( Fig. 4E ). Except for the cheliped fixed finger, the characteristics of these two paratypes are almost identical to the allotype, with minor differences in some setae on cheliped and pereopods.

Etymology. The name is derived from the Latin “ setosa ” (hairy), referring to the numerous long setae on the male uropod.

Type locality. Jihuei, Taitung County, eastern Taiwan.

Distribution. It is only known from Shitiping, Jialulan and Jihuei, eastern Taiwan.

Remarks. The two members of Paraleptochelia , P. gadgeti (West Australia) and P. magnispina (East Tanzania), are from the Indian Ocean, whereas the present species, P. setosa sp. nov., is the first species in the genus reported outside of this region.

Of the three species, P. gadgeti is readily distinguished by having a longer and more slender body (ten times longer than wide, comparing to seven in P. magnispina and six in P. setosa ), longer antennule and cheliped, and a unique trapezoidal apophysis on the fixed finger of the male cheliped ( Edgar 2012). Morphologically, the present species is somewhat more similar to P. magnispina , especially in male habitus and cheliped. However, P. setosa differs from the latter species by having: 1) a less slender body in both sexes; 2) the male antennule flagellum having five articles, compared to six in P. magnispina ; 3) the male antenna article-2 lacks a ventral spine; 4) the female maxilliped endite inner margin has two coupling hooks (versus absent in P. magnispina ); 5) the cheliped fixed finger has one subtriangular middle denticle on the incisive margin in some male individuals; 6) the female pereopods 4–6 carpus has four distal spines (versus three in P. magnispina ); 7) the female pereopod-6 ischium has two ventral setae (versus one in P. magnispina ); 8) the uropod exopod and endopod have two and five articles, respectively, in both sexes (versus one and four in P. magnispina , respectively) ( Guţu 2016; Table 1).

Figures

FIGURE 1. Paraleptochelia setosa sp. nov. Holotype (NMNS 8288-01), female: A, body dorsal view; C, right antennule; D, right antenna; E, left mandible; F, right mandible; G, maxillule. Paratype (NMNS 8288-06), male: B, body dorsal view. Scale: A, B, 1 mm; C–G, 0.1 mm.

FIGURE 2. Paraleptochelia setosa sp. nov. Holotype (NMNS 8288-01), female: A, maxilliped; B, maxilliped endite; C, right cheliped; D–F, right pereopods 1–3. Scale: A–F, 0.1 mm.

FIGURE 3. Paraleptochelia setosa sp. nov. Holotype (NMNS 8288-01), female: A–C, left pereopods 4–6; D, left pleopod-1; E, right uropod. Scale: A–E, 0.1 mm.

FIGURE 4. Paraleptochelia setosa sp. nov. Allotype (NMNS 8288-02), male: A, right antennule; C, left cheliped; D, left cheliped dactylus; F–G, right pereopods 1–2. Paratype (NMNS 8288-03), male: B, right antenna. Paratype (NMNS 8288-04), male: E, left cheliped. Scale: A, C, E, 0.5 mm; B, D, 0.1 mm; F–G, 0.25 mm.

FIGURE 5. Paraleptochelia setosa sp. nov. Allotype (NMNS 8288-02), male: A–B, left pereopods 3–4; C–D, right pereopods 5–6; F, right uropod. Paratype (NMNS 8288-03), male: E, right pleopod-1. Scale: A–F, 0.1 mm.