Leptochelia taitungensis, Tzeng, You-Wei & Hsueh, Pan-Wen, 2015

Tzeng, You-Wei & Hsueh, Pan-Wen, 2015, Additions of new species and records to the Tanaidomorpha (Crustacea: Tanaidacea) of Taiwan, Zootaxa 4013 (1), pp. 27-50 : 28-36

publication ID	https://doi.org/ 10.11646/zootaxa.4013.1.2
publication LSID	lsid:zoobank.org:pub:6ABAB8AE-6E27-40D5-8231-35BF205631A5
DOI	https://doi.org/10.5281/zenodo.5616434
persistent identifier	https://treatment.plazi.org/id/03CF87E7-FF84-E527-98D7-3A8EFAB2AA6C
treatment provided by	Plazi
scientific name	Leptochelia taitungensis
status	sp. nov.

Treatment

Leptochelia taitungensis View in CoL sp. nov.

Figs 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5

Material examined. Holotype: non-ovigerous female ( NMNS 7434–1), 3.3 mm, Jialulan (22°48'10.2"N, 121°11'57.0"E), eastern Taiwan, intertidal, washing from brown alga Padina sp., collected by You-Wei Tzeng, 10 August 2010.

Allotype: male ( NMNS 7434–2), 3.1 mm, Shanyuan (22°50'12.6"N, 121°11'18.0"E), eastern Taiwan, intertidal, washing from green alga Boodlea sp., collected by You-Wei Tzeng, 23 August 2010.

Paratypes: one non-ovigerous female ( NMNS 7434–3), 3.2 mm, Jihuei (23°06'54.9"N, 121°24'16.3"E), eastern Taiwan, intertidal, washing from polychaete-worm tube of Eunice taoi Hsueh & Li , collected by You-Wei Tzeng, 25 March 2011; one male ( NMNS 7434–4), 2.8 mm, Jihuei (23°06'54.9"N, 121°24'16.3"E), eastern Taiwan, intertidal, collected by You-Wei Tzeng, 6 October 2010; one non-ovigerous female ( NMNS 7434–5), 2.1 mm, and one non-ovigerous female ( NMNS 7434–6), 2.2 mm, same collection data as holotype; one ovigerous female ( NMNS 7434–7), 3.9 mm, one non-ovigerous female ( NMNS 7434–8), 2.5 mm, and one non-ovigerous female ( NMNS 7434–9), 3.5 mm, Jialulan (22°48'10.2"N, 121°11'57.0"E), eastern Taiwan, intertidal, collected by You- Wei Tzeng, 23 August 2010; one post-ovigerous female ( NMNS 7434–10), 3.2 mm, Jihuei (23°06'54.9"N, 121°24'16.3"E), eastern Taiwan, intertidal, collected by You-Wei Tzeng, 7 October 2010; one non-ovigerous female ( NMNS 7434–11), 2.5 mm, one non-ovigerous female ( NMNS 7434–12), 3.6 mm, one non-ovigerous female ( NMNS 7434–13), 2.9 mm, and five female ( NMNS 7434–14), Shanyuan (22°50'12.6"N, 121°11'18.0"E), eastern Taiwan, intertidal, collected by You-Wei Tzeng, 23 August 2010.

Diagnosis. Female: Cephalothorax 1.3 times as long as wide. Maxilliped basis with four distal setae, endite with three long distal spines, innermost shorter. Cheliped basis 1.6 times as long as wide; carpus twice as long as wide. Pereopod 1 basis four times as long as wide. Pereopod 6 with a row of distal pectinate setae on propodus. Uropod exopod one-articled, 0.5 times as long as endopod article 1; endopod three- to five-articled. Male: Antennule flagellum seven-articled, article 1 with ten aesthetascs, articles 2–5 and 7 with five aesthetascs, article 6 with eight aesthetascs. Cheliped 0.5 times as long as body; fixed finger incisive margin with two triangular processes. Uropod exopod two-articled, longer than endopod article 1; endopod five-articled.

Description. Female, holotype: Habitus ( Fig. 1 View FIGURE 1 A) body subcylindrical, over six times as long as wide. Cephalothorax oval-shaped, about 0.2 times as long as body and 1.3 times as long as wide, lateral margin with one seta adjacent to eye and one medial seta. Pereonites wider than long, with one or two lateral setae; pereonite 1 short, 0.35 times as long as wide; pereonite 2 longer than pereonite 1 but slightly narrower, 0.45 times as long as wide; pereonite 3 longer than pereonite 2, 0.55 times as long as wide; pereonite 4 longer than pereonite 3, about 0.7 times as long as wide; pereonite 5 longest, 0.8 times as long as wide; pereonite 6 as long as pereonite 3. Pleon about 0.17 times as long as body; pleonites wider than pereonites, with one lateral seta each side. Pleotelson narrower than pereonites, posterior margin with one small medial process, the process with one terminal seta and two adjacent setae on each side.

Antennule ( Fig. 1 View FIGURE 1 B) three-articled plus distinct distal cap-like segment, almost 0.6 times as long as cephalothorax; article 1 longest, 0.55 times as total length, outer margin with one proximal broom seta, one median seta, three median broom setae, one distal seta, and three distal broom setae, inner margin with one median seta; article 2 0.4 times as long as article 1, with one distal outer seta, one distal inner seta and one distal inner broom seta; article 3 shorter than article 2, with one distal seta, one distal broom setae and one distal aesthetasc; cap-like segment with five distal setae and one distal broom seta.

Antenna ( Fig. 1 View FIGURE 1 C) six-articled; article 1 with one distodorsal seta; article 2 with one strong distodorsal seta and one thorn-like distoventral spine; article 3 with one strong distoventral spine; article 4 longest, 0.4 times as long as antenna, with two distodorsal setae, one distodorsal broom seta and one distal outer broom seta; article 5 with one distodorsal and one distoventral seta; article 6 very short, with four distal setae.

Labrum ( Fig. 1 View FIGURE 1 D) sub-quadrate, covered by long setules. Left mandible ( Fig. 1 View FIGURE 1 E) lacinia mobilis large, subtriangular, superior margin crenulated; incisor smooth, with blunt acuminate apex; molar robust, with distal ridges. Right mandible ( Fig. 1 View FIGURE 1 F) without lacinia mobilis; incisor with superior margin crenulated and apex bifid; molar not studied. Labium ( Fig. 1 View FIGURE 1 G) outer and inner lobes setulose. Maxillule ( Fig. 1 View FIGURE 1 H) palp with two distal setae; endite with nine distal spines, superodistal margin covered with setules and setae, inner margin with five setae. Maxilliped ( Fig. 2 View FIGURE 2 A) basis with four long distal setae; endite ( Fig. 2 View FIGURE 2 B) outer margin setulose, inner margin with two coupling hooks, distal margin with strong lateral seta and three blunt spines, the innermost shorter than other two; palp article 1 naked; article 2 inner margin with four setae; article 3 inner margin with eight setae; article 4 with eight distal setae.

Cheliped ( Fig. 2 View FIGURE 2 C) about 0.25 times as long as body, attached to cephalothorax via sclerite; sclerite triangular, with one outer seta; basis 1.6 times as long as wide, asetose; merus triangular, with three ventral setae; carpus 1.2 times as long as basis, over 2.0 times as long as wide, with three dorsal and three distoventral setae; propodus plus fixed finger as long as basis, 2.0 times as long as wide, with one outer and one inner seta near articulation with dactylus, a row of four inner setae and a row inner setules ( Fig. 2 View FIGURE 2 D), fixed finger about 0.25 times as long as propodus, ventral margin with two setae, incisive margin with one large lamellate process and three setae; dactylus curved, with one inner seta.

Pereopod 1 ( Fig. 2 View FIGURE 2 E) coxa with one setae; basis slightly curved, four times as long as wide, with one dorsoproximal seta; ischium wider than long, with one ventral seta; merus 0.35 times as long as basis, with one dorsal seta; carpus slightly shorter than merus, with two dorsal setae and one distoventral seta; propodus 0.7 times as long as basis, with four distal setae; dactylus thin and slightly curved, unguis about 0.4 times as long as dactylus, together longer than propodus. Pereopod 2 ( Fig. 2 View FIGURE 2 F) coxa with one setae; basis 2.5 times as long as wide, with three dorsoproximal broom setae; ischium wider than long, with one ventral seta; merus 0.35 times as long as basis, with one distoventral spine; carpus shorter than merus, with two distodorsal setae and one small distoventral spine; propodus 0.6 as long as basis, with four distodorsal setae and one distoventral spine; dactylus short, together with unguis shorter than propodus. Pereopod 3 ( Fig. 2 View FIGURE 2 G, figures and description based on right pereopod 3 of paratype NMNS7434–3) coxa with one setae; basis 2.4 times as long as wide, asetose; ischium with one ventral seta; merus 0.4 times as long as basis, with one distoventral seta and one distoventral spine; carpus shorter than merus, with two distodorsal setae, one distoventral seta and one small distoventral spine; propodus 0.7 times as long as basis, with two distodorsal setae and one small distoventral spine; dactylus and unguis short.

Pereopod 4 ( Fig. 3 View FIGURE 3 A) coxa asetose; basis thick, less than twice as long as wide, with three dorsoproximal broom setae; ischium wider than long, with one ventral seta; merus about 0.4 times as long as basis, with two distoventral spines; carpus shorter than merus, with one distodorsal setae, distal margin with one medial and two lateral spines; propodus longer than carpus but shorter than merus, 2.5 times as long as wide, with three distodorsal setae, and two ventro-subdistal spines; dactylus and unguis fused to a claw, together shorter than propodus. Pereopod 5 ( Fig. 3 View FIGURE 3 B) similar to pereopod 4 but basis with two ventral broom setae, ischium with two ventral setae, and propodus with four distodorsal setae. Pereopod 6 ( Fig. 3 View FIGURE 3 C) similar to pereopod 4 but basis asetose, propodus ( Fig. 3 View FIGURE 3 D) distodorsal margin with two long seta and five strong pectinate setae.

Pleopod 1 ( Fig. 3 View FIGURE 3 E) basal article with one inner plumose seta; exopod with 20 outer plumose setae and one outer proximal plumose seta; endopod with twelve outer plumose setae, one outer proximal plumose seta and one inner medial plumose seta. Pleopod 2, 3 and 5 (not figured) similar to pleopod 1. Pleopod 4 (not figured) similar to pleopod 1 but endopod with ten outer plumose setae and one outer proximal plumose seta.

Uropod ( Fig. 3 View FIGURE 3 F) basal article asetose; exopod one-articled, 0.5 times as long as endopod article 1, with one seta on outer mid-margin and two distal setae; endopod five-articled, articles 1–2 with two distal setae, article 3 asetose, article 4 with one distal seta and two broom setae, article 5 with four distal setae and two broom setae.

Variations. Almost all large adults have five uropod endopod articles. However, some smaller individuals have fewer or uneven numbers of left and right uropod endopod articles (i.e., five and four in NMNS7434–3; four and three in NMNS7434–5; three and three in NMNS7434–6; four and four in NMNS7434–8).

Male allotype: Habitus ( Fig. 4 View FIGURE 4 A) body more dorsoventrally flattened than female, five times as long as wide. Cephalothorax over 0.2 times as long as body, eyes large. Pereonites wider than long; pereonite 1 short, 0.25 times as long as wide; pereonite 2 longer but as wide as pereonite 1, 0.3 times as long as wide; pereonite 3 longer and narrower than pereonite 2, 0.45 times as long as wide; pereonite 4 the longest, narrower than pereonite 3, 0.7 times as long as wide; pereonite 5 the narrowest, 0.8 times as long as wide; pereonite 6 shorter but wider than pereonite 5, 0.4 times as long as wide. Pleon 0.2 times as long as body, narrower than pereon; pleonites all about the same length. Pleotelson narrower than pleonite 5, 0.7 times as long as wide, with one lateroproximal seta, one laterodistal seta and one laterodistal broom seta, posterior margin with one small medial process, the process with two terminal setae.

Antennule ( Fig. 4 View FIGURE 4 B) long, over twice as long as cephalothorax; peduncle three-articled, article 1 3.0 times as long as wide, with two distodorsal setae; article 2 0.6 times as long as article 1 and narrower, with one distal outer seta, one distoventral seta and two distoventral broom setae; article 3 0.6 times as long as article 2 and narrower, with two distodorsal setae; flagellum seven-articled, each article about 0.5 times as long as peduncle article 3, article 1 with one ventroproximal and one distoventral cluster of five aesthetascs, articles 2–5 each with one distoventral cluster of five aesthetascs, article 6 with one distoventral cluster of eight aesthetascs; article 7 with five distal setae and five distal aesthetascs.

Antenna ( Fig. 4 View FIGURE 4 C) only reaching distal peduncle article 1 of antennule; article 1 short, asetose; article 2 2.0 times as long as article 1, with one distodorsal seta; article 3 1.8 times as long as article 2, with one distodorsal seta and one distoventral broom seta; article 4 a little shorter than article 3, with one distodorsal seta, one lateral seta, two distoventral setae and one distoventral broom setae; article 5 the longest, 2.0 times as long as article 3, with one distodorsal seta and one distoventral seta; article 6 very small, with six distal setae.

Mouthparts reduced. Maxilliped present but almost fused with cephalothorax.

Cheliped ( Fig. 4 View FIGURE 4 D) larger than female, over 0.5 times as long as body, attached to cephalothorax via sclerite; sclerite triangular, with one outer seta; basis less than twice as long as wide, asetose; merus triangular, with one outer seta; carpus long, three times as long as wide, with four short dorsal setae and two long ventromedial setae; propodus palm less than twice as long as wide, with one oblique row of inner setae ( Fig. 4 View FIGURE 4 E, one long seta and 19 short setae in this row), fixed finger about 0.5 times as long as propodus, distally curved, with four setae on ventral margin, one lateral seta, three setae and two triangular processes on incisive margin; dactylus curved, about as long as fixed finger, with one dorsoproximal seta, with serrations and eight small spines on incisive margin.

Pereopod 1 ( Fig. 5 View FIGURE 5 A) coxa asetose; basis long and slender, slightly curved, 5.0 times as long as wide, with one dorsoproximal seta and one dorsoproximal broom seta; ischium wider than long, with one ventral seta; merus 0.3 times as long as basis, with two distodorsal and two distoventral setae; carpus longer than merus, with three distodorsal setae and one distoventral seta; propodus slender, 0.65 times as long as basis, with three distodorsal setae, one distodorsal short seta and one distoventral seta; dactylus thin and slightly curved, unguis about 0.4 times as long as dactylus, together shorter than propodus.

Pereopod 2 ( Fig. 5 View FIGURE 5 B) coxa with one seta; basis 4.0 times as long as wide, with one dorsoproximal seta and one dorsoproximal broom seta; ischium wider than long, with two ventral setae; merus 0.3 times as long as basis, with one distoventral seta and one distoventral spine; carpus longer than merus, with two distodorsal setae, one distoventral seta and one distoventral spine; propodus 0.6 times as long as basis, with three distodorsal setae, one distodorsal short setae and one distoventral spine; dactylus and unguis short. Pereopod 3 ( Fig. 5 View FIGURE 5 C) similar to pereopod 2 but basis without dorsoproximal broom seta, ischium with three ventral setae.

Pereopod 4 ( Fig. 5 View FIGURE 5 D) coxa with one seta; basis stout, 2.5 times as long as wide, with two dorsoproximal broom and one dorsomedial seta; ischium wider than long, with one ventral seta; merus 0.3 times as long as basis, with two distoventral spines; carpus longer than merus, distal margin with two dorsal setae, two outer spines and two inner spines; propodus 0.6 times as long as basis, with four distodorsal setae and two distoventral spines; dactylus and unguis fused to a claw, together shorter than propodus. Pereopod 5 ( Fig. 5 View FIGURE 5 E) similar to pereopod 4 but coxa asetose, basis with one dorsoproximal broom seta, ischium with two ventral setae, carpus with large distodorsal spine. Pereopod 6 ( Fig. 5 View FIGURE 5 F) similar to pereopod 5 but basis stouter and propodus with five distodorsal pectinate setae.

Pleopods ( Fig. 5 View FIGURE 5 G) basal article with one inner plumose seta; exopod with 26–28 outer plumose setae; endopod with 18–19 outer plumose setae and one inner medial plumose seta.

Uropod ( Fig. 5 View FIGURE 5 H) basal article 1.4 times as long as wide, with four distal outer setae; exopod two-articled, longer than endopod article 1, article 1 with one distodorsal seta, article 2 with two distal setae; endopod article 1 with five distal setae and one inner distal broom seta, article 2 longer than article 1, with four distal setae and one inner distal broom seta, article 3 longer than article 2, with four distal setae, article 4 longer than article 3, with two distal setae and one inner distal broom seta, article 5 longer than article 4, with five distal setae and one inner distal broom seta.

Etymology. The name is derived from Taitung County in Taiwan, where the species was collected exclusively on coasts of this County.

Type locality. Jialulan, eastern Taiwan.

Distribution. Jialulan, Shanyuan and Jihuei, Taitung County, eastern Taiwan.

Remarks. Males of the present species possess compact and robust chelipeds, which is a distinctive morphological character of the Leptochelia dubia / savignyi group ( Edgar 2012; Anderson 2013) and Leptochelia taitungensis sp. nov. should be assigned to this group as well. According to Anderson (2013: 385) and Jarquín- González et al. (2015), eighteen species in the genus were included to this species group. Of those species, only four ( Leptochelia daggi Bamber, 2005 and L. opteros Bamber, 2008 from Australia, L. savignyi (Krøyer) from Europe, and L. tarda Larsen & Rayment, 2002 from India) have a similar morphology in the male chelipeds and the same number of maxilliped basis distal setae (four) and uropod exopod articles of the female as L. taitungensis ( Table 2 View TABLE 2 ). However, the present species can be distinguished from the two Australian species by the female uropod exopod only reaching half-length of exopod article 1, the longer cheliped basis (1.6 times as long as wide), and males having a two-articled uropod exopod. Leptochelia taitungensis also differs from the European species by female having up to five uropod endopod articles and male having a two-articled uropod exopod. The Thailand species, Leptochelia tarda , is very similar to the present species but can be separated by having shorter distal spines on maxilliped endite and male having one-articled uropod exopod, compared to long distal spines on maxilliped endite and male with two-articled uropod exopod in the present species ( Bamber, 2005: figs 37G, 38A, H; Bamber, 2008: figs 30F, H, 31A; Larsen & Rayment: figs 5G, 6F, L; present study: Figs 1 View FIGURE 1 H, 2A, B, 3C, D, F, Table 2 View TABLE 2 ).