Zeuxo shitipingensis, 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 : 38-48

Zeuxo shitipingensis sp. nov.

Figs 6–11

Material examined. Holotype: non-ovigerous female ( NMNS 7434–15), 3.2 mm, Shitiping (23°28'57.4"N, 121°30'46.9"E), eastern Taiwan, intertidal, washing from red alga Jania sp., collected by You-Wei Tzeng, 27 August 2010.

Allotype: male ( NMNS 7434–23), 1.8 mm, same collection data as holotype.

Paratypes: one ovigerous female ( NMNS 7434–16), 2.5 mm, one non-ovigerous female ( NMNS 7434–19), 2.8 mm, one non-ovigerous female ( NMNS 7434–20), 2.8 mm, eleven females ( NMNS 7434–21), and two males and two females ( NMNS 7434–28), same collection data as holotype; one ovigerous female ( NMNS 7434–17), 3.4 mm, and one male ( NMNS 7434–25), Shitiping (23°28'57.4"N, 121°30'46.9"E), eastern Taiwan, intertidal, washing from brown alga Padina sp., collected by You-Wei Tzeng, 27 August 2010; one non-ovigerous female ( NMNS 7434–18), Shitiping (23°28'57.4"N, 121°30'46.9"E), eastern Taiwan, intertidal, washing from green alga Halimeda sp., collected by You-Wei Tzeng, 27 August 2010; one ovigerous female ( NMNS 7434–22), 2.0 mm, Jihuei (23°06'54.9"N, 121°24'16.3"E), eastern Taiwan, intertidal, collected by You-Wei Tzeng, 9 October 2010; one male ( NMNS 7434–24), Shitiping (23°28'57.4"N, 121°30'46.9"E), eastern Taiwan, intertidal, washing from red alga Hypnea pannosa J. Agardh , collected by You-Wei Tzeng, 26 March 2011; one ovigerous female ( NMNS 7434–25), 3.1 mm, one ovigerous female ( NMNS 7434–26), 2.9 mm, and two male and two female ( NMNS 7434–27), Shanyuan (22°50'12.6"N, 121°11'18.0"E), eastern Taiwan, intertidal, washing from green alga Chlorodesmis sp., 23 August 2010.

Diagnosis. Female: Antennule article 4 with three aesthetascs. Left mandible with wide and crenulated lacinia mobilis. Right mandible with narrow and elongate lacinia mobilis. Pereopod 1 coxa with acuminate process. Pereopods 4–6 merus with one distodorsal seta. Pereopod 6 propodus with six leaf-like distal setae. Pleopod basis with three to eight outer plumose setae and one inner plumose seta; endopod inner margin with one plumose seta. Uropod endopod five- or six-articled.

Description. Female, holotype: Habitus ( Fig. 6 A) body subcylindrical, about 6.0 times as long as wide. Cephalothorax oval-shaped, about 0.2 times as long as body, about 1.1 times as long as wide. Pereonites all shorter than wide, with three lateral setae each side; pereonite 1 short, 0.3 times as long as wide; pereonite 2 longer than pereonite 1, 0.4 times as long as wide; pereonites 3 about 2.0 times as long as pereonite 1; pereonite 4 longer than pereonite 3, 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 0.16 times as long as body; pleonites 1–3 with three lateral plumose setae each side; pleonites 4–5 short and narrower than pleonites 1–3, with two lateral setae. Pleotelson shorter than wide, posterior margin with six setae and one medial process.

Antennule ( Fig. 6 B) about 0.6 times as long as cephalothorax; article 1 more than 0.5 times total length, with one lateral, six distal setae and one distal broom seta; article 2 about 0.5 times as long as article 1, with four distal setae and three broom setae; article 3 shorter than article 2, with three distal setae and one broom seta; article 4 with eight setae and three aesthetascs.

Antenna ( Fig. 6 C) articles 1 and 3 short and asetose; article 2 about twice as long as article 1, with two lateral setae; article 4 longest, with four distal setae; article 5 as long as article 2, with three distal setae and three broom setae; articles 6–7 very short, with three distal setae on article 6 and nine distal setae on article 7.

Labrum ( Fig. 6 D) rounded, covered by setae and setules. Left mandible ( Fig. 6 E) lacinia mobilis large and triangular, superiorly crenulated; setal row with two setae; incisor smooth, with subacute apex; molar robust, with distal ridges. Right mandible ( Fig. 6 F) lacinia mobilis narrow and elongate; setal row with one seta; incisor with apical denticles; molar robust, with distal ridges. Labium ( Fig. 6 G) inner lobe covered by setules; outer lobe with distal margin covered by setules, terminal process oval, with two distal setae. Maxillule ( Fig. 6 H) palp with two distal setae (in holotype); endite with eight distal spines, superodistal margin with setules. Maxilla not studied. Maxilliped ( Fig. 7 A) basis with one distal seta; endite ( Fig. 7 B) outer margin denticulate, superior outer margin covered by setules, superior margin with four strong plumose setae; palp article 1 outer margin with one seta; article 2 inner distal margin with five setae and three serrated setae, outer margin with one plumose seta; article 3 inner margin with eight setae and eight serrated setae; article 4 with nine distal setae and one outer seta.

Cheliped ( Fig. 7 C) about 0.25 times as long as body, attached to cephalothorax via sclerite; sclerite triangular, with one anterior seta; basis 1.6 times as long as wide, with one distodorsal and one distoventral seta; merus triangular, with two ventral setae; carpus 1.8 times as long as wide, with one dorsal, two distodorsal and three ventral setae; propodus with three outer setae and one inner seta near articulation with dactylus, fixed finger ventral margin with four setae, incisive margin with seven setae; dactylus curved, incisive margin with four denticles, unguis short.

Pereopod 1 ( Fig. 7 D) coxa with prominent anterior process with three setae; ischio-basis long, five times as long as wide, with one dorsoproximal and one distoventral seta; merus 0.3 times as long as basis, with one distodorsal and one distoventral seta; carpus slightly longer than merus, with one distodorsal seta; propodus 0.7 times as long as basis, with one dorsal, one distodorsal and three distoventral setae; unguis more than 0.5 times dactylus length, together shorter than propodus. Pereopod 2 ( Fig. 7 E) coxa without prominent process, with two setae; ischio-basis three times as long as wide, with two dorsoproximal setae, one dorsoproximal broom setae and one distoventral setae; merus 0.45 times as long as basis, with one distodorsal seta, ventral margin setulose, two distoventral setae, and one distoventral spine; carpus shorter than merus, with one distodorsal and one distoventral seta, ventral margin setulose, distal margin with four outer and two inner spines; propodus as long as merus, dorsal margin with one broom seta and two distal setae, ventral margin with one distal seta and one distal spine; dactylus and unguis shorter than propodus. Pereopod 3 ( Fig. 7 F) similar to pereopod 2 but ischio-basis with two dorsoproximal setae and two dorsomedial broom setae, carpus distal margin with five outer spines, and propodus dorsal margin without broom seta, with only one distal seta.

Pereopod 4 ( Fig. 8 A) coxa with one seta; ischio-basis three times as long as wide, with two dorsal and two ventral broom setae, and two distoventral setae; merus about 0.5 times as long as basis, with one distodorsal, one distoventral seta and two distoventral spines, ventral margin setulose; carpus shorter than merus, with three distodorsal setae, distal margin with three outer and two inner spines, ventral margin setulose; propodus as long as merus, with one dorsal broom seta and one ventral seta, distal margin with three setae, two distodorsal and one distoventral; dactylus and unguis fused to a hook-like claw, with paired row of distal setules and a spine and about four small spine on ventral margin. Pereopod 5 ( Fig. 8 B) similar to pereopod 4 but ischio-basis with three distoventral setae. Pereopod 6 ( Fig. 8 C) similar to pereopod 4 but ischio-basis without ventral broom setae, propodus distal margin with a comb-like row of six leaf-like setae, without distoventral seta.

Pleopods ( Fig. 8 D) basal article with four to six outer and one inner plumose setae; exopod with 29 outer plumose setae; endopod with one leaf-like strong distal plumose seta, 13 outer and one inner plumose seta.

Uropod ( Fig. 8 E) basal article with three distal setae; endopod six-articled, article 1 asetose, article 2 with three distal setae, article 3 with one distal seta and one distal broom seta, article 4 with four distal setae and one distal broom seta, article 5 with three distal setae and one distal broom seta, article 6 with six distal setae and two distal broom setae.

Variations. The number of maxillule palp distal setae ranges from two to five and the pleopod basis outer margin plumose setae vary within the same individual and between individuals; for example, the holotype has four to six outer plumose setae, whereas some paratypes have three to six, four to seven, five to eight, or seven to eight outer plumose setae in the same specimen. The uropod endopod can have five articles in some smaller individuals.

Male allotype: Habitus ( Fig. 9 A) body subcylindrical but stouter than female, about 5.0 times as long as wide. Cephalothorax relatively larger than female, subtriangular, 0.25 times as long as body. Pereonites with two lateral setae each side, all shorter than wide; pereonite 1 short, 0.3 times as long as wide; pereonite 2 longer than pereonite 1, 0.4 times as long as wide; pereonite 3 longer than pereonite 2, 0.45 times as long as wide; pereonite 4 longer than pereonite 3, 0.5 times as long as wide; pereonite 5 longest, 0.65 times as long as wide; pereonite 6 narrowest, 0.4 times as long as wide. Pleon about 0.2 times as long as body. Pleonites 1–3 wider than pereonite 6, with three lateral plumose setae at each side; pleonites 4–5 short and narrower than pleonites 1–3, with two lateral setae. Pleotelson shorter than wide, posterior margin with four setae.

Antennule ( Fig. 9 B) as long as cephalothorax; article 1 long, about 0.65 times as long as antennule, with three outer proximal broom setae, one inner proximal seta, two outer distal setae, two outer distal broom setae, and two inner distal setae; article 2 0.36 times as long as article 1 with two outer and two inner distal setae; article 3 0.45 as long as article 2, with four distal setae and one distal broom seta; article 4 very small, with seven setae, one broom seta and five aesthetascs.

Antenna ( Fig. 9 C) articles 1 and 3 short and asetose; article 2 about twice as long as article 1, with two dorsomedial setae, one distodorsal seta, and one distoventral broom seta; article 4 longest, with two distodorsal setae, one distoventral seta and one distoventral broom seta; article 5 shorter than article 2, with three distoventral setae and one distoventral broom seta; articles 6–7 very short, with four distal setae on article 6 and seven distal setae on article 7.

Labrum not studied. Left mandible ( Fig. 9 D) lacinia mobilis large, superiorly crenulated; setal row with two setae; incisor smooth, with subacute apex; molar robust, with distal ridges. Right mandible not studied. Labium (not figured) similar to female. Maxillule palp ( Fig. 9 F) with three distal setae; endite ( Fig. 9 E) with eight distal spines, superodistal margin covered by setules. Maxilla not studied. Maxilliped ( Fig. 9 G) basis outer margin denticulate; endite superior outer margin covered by setules, superior margin with four strong plumose setae; palp article 1 outer margin with one seta; article 2 inner distal margin with five setae and three strong serrated setae; article 3 inner margin with four setae and eight serrated setae; article 4 with nine distal setae and one outer seta.

Cheliped ( Fig 10 A) large, about 0.65 times as long as body, attached to cephalothorax via sclerite; sclerite triangular, with one anterior seta; basis short, 1.1 times as long as wide, with one distoventral seta; merus triangular, with two ventral setae; carpus thick, 1.3 times as long as wide, with one dorsoproximal, three distodorsal and three distoventral setae; palm longer than wide, with two inner setae near articulation with dactylus, fixed finger triangular, recurved, almost vertical to cheliped body, 1.2 times as long as wide, with three setae on incisive margin near articulation with dactylus, four setae on ventral margin and five setae on incisive margin; dactylus bent proximally.

Pereopod 1 ( Fig. 10 B) coxa with prominent anterior process with three setae; ischio-basis long and slender, 6.0 times as long as wide, with one dorsoproximal seta, one dorsoproximal broom seta and one distoventral seta; merus 0.3 times as long as basis, with one distodorsal and one distoventral seta; carpus longer than merus, with one distodorsal seta; propodus 0.7 times as long as basis, with one dorsal, one distodorsal and three distoventral setae; unguis more than 0.5 times as long as dactylus, together combined shorter than propodus. Pereopod 2 ( Fig. 10 C) coxa without prominent process, with two setae; ischio-basis 3.5 times as long as wide, with one dorsoproximal setae, two dorsoproximal broom setae and two distoventral setae; merus 0.45 times as long as basis, with one distodorsal seta, two distoventral setae, and one distoventral spine; carpus shorter than merus, with one distodorsal and one distoventral seta, ventral margin setulose, distal margin with four outer and two inner spine; propodus as long as merus, with one distodorsal seta, one ventral seta and one distoventral spine; dactylus and unguis shorter than propodus. Pereopod 3 ( Fig. 10 D) very similar to pereopod 2.

Pereopod 4 ( Fig. 10 E) coxa not studied; ischio-basis 3.3 times as long as wide, with two dorsal and two ventral broom setae, and three distoventral setae; merus about 0.45 times as long as basis, with one distodorsal, one distoventral seta and two distoventral spines; carpus shorter than merus, with three distodorsal setae, distal margin with three outer and two inner spines; propodus as long as merus, with two distodorsal setae, one distodorsal broom seta, and one ventral seta; dactylus and unguis fused to a hook-like claw, with a paired row of distal setules and a spine on ventral margin. Pereopod 5 ( Fig. 10 F) very similar to pereopod 4. Pereopod 6 ( Fig. 11 A) similar to pereopod 4 but ischio-basis without ventral broom setae, propodus with three distodorsal setae and distal margin with a comb-like row of five leaf-like setae.

Pleopods ( Fig. 11 B) all with same setae number; basal article with six outer and one inner plumose setae; exopod with 25 outer plumose setae; endopod with one leaf-like strong distal plumose seta, ten outer and one inner plumose seta.

Uropod ( Fig. 11 C) basal article with six distal setae; endopod article 1 asetose, article 2 with two distal setae, article 3 with four distal seta, article 4 with three distal setae and one distal broom seta, article 5 with six distal setae and two distal broom setae.

Etymology. The name is derived from the name of location where most individuals of the present species are collected.

Type locality. Shitiping, eastern Taiwan.

Distribution. Shitiping, Shanyuan and Jihuei, eastern Taiwan.

......continued on the next page Remarks. Of thirty-one species of the genus, eight have similar left and right mandible lacinia mobilis morphology to that of the Zeuxo shitipingensis sp. nov. ( Table 3 ); all these species have a wide and superiorly crenulated left mandibular lacinia mobilis, and a narrow and elongated right mandibular lacinia mobilis. Zeuxo normani ( Richardson, 1905) is the most similar of these eight species also having three aesthetascs on the antennule terminal article, a prominent anterior process on pereopod 1 coxa, six distal leaf-like setae on the pereopod 6 propodus, and one seta on the pleopod basis inner margin. Nevertheless, the present species can be distinguished from Z. normani by having a triangular left mandible lacinia mobilis (which is morphologically similar to that of Zeuxo zorro Bamber & Bird, 1997 ), only one seta on the pleopod endopod inner margin, and up to six uropod endopod articles in adult specimens.

Zeuxo shitipingensis is occasionally found co-occurring with Z. zorro at Shitiping and Jihuei in eastern Taiwan. However, Zeuxo zorro can be distinguished from Z. shitipingensis by having a generally smaller body size (1.9 mm to 2.3 mm in the collected specimen), no seta on the pleopod basis inner margin, and the uropod endopod with only three articles.

The present species fits quite well with diagnosis of the subgenus Parazeuxo Sieg, 1980 (i.e., pereopod 4–6 merus having only one distodorsal seta, carpus having three outer spines and two inner spines, and pleopod endopod having one inner seta steadily) rather than that of the subgenus Zeuxo Sieg, 1980 . However, the two subgenera have been considered invalid recently by Larsen (2014) and Larsen et al. (2014) due to the frequent variations of pleopod and pereopod 4–6 merus setation of Zeuxo species.

Figures

FIGURE 6. Zeuxo shitipingensis sp. nov. Holotype (NMNS 7434 – 15) female: A body dorsal view; B right antennule; C right antenna; D labrum; E left mandible; F right mandible; G labium; H left maxillule. Scale: A, 1 mm; B – H, 0.1 mm.

FIGURE 7. Zeuxo shitipingensis sp. nov. Holotype (NMNS 7434 – 15) female: A right maxilliped; B right maxilliped endite; C right cheliped; D – F right pereopod 1 – 3, respectively. Scale: A – F, 0.1 mm.

FIGURE 8. Zeuxo shitipingensis sp. nov. Holotype (NMNS 7434 – 15) female: A left pereopod 4; B – C right pereopod 5 – 6, respectively; D right pleopod 1 (All setae are plumose. Only some of the setules are showed.); E right uropod. Scale: A – E, 0.1 mm.

FIGURE 9. Zeuxo shitipingensis sp. nov. Allotype (NMNS 7434 – 23) male: A body dorsal view; B right antennule; C left antenna; D left mandible; E left maxillule endite; F left maxillule palp; G left maxilliped. Scale: A – G, 0.1 mm.

FIGURE 10. Zeuxo shitipingensis sp. nov. Allotype (NMNS 7434 – 23) male: A right cheliped; B – F right pereopod 1 – 5, respectively. Scale: A – F, 0.1 mm.

FIGURE 11. Zeuxo shitipingensis sp. nov. Allotype (NMNS 7434 – 23) male: A right pereopod 6; B right pleopod 3 (All setae are plumose. Only some of the setules are showed.); F right uropod. Scale: A – C, 0.1 mm.

Tables

TABLE 3. Key morphological characters of female of all species described for Zeuxo. References: Bamber (1990), Bamber (2005), Bamber (2006), Bamber (2008), Bamber (2012), Bamber & Bird (1997), Bamber & Chatterjee (2010), Bird (2008), Edgar (2008), Kudinova-Pasternak (1989), Larsen (2014), Sieg (1980), Templeton (1840), Thomson (1879). NA = not available from original description.

	antennule terminal article aesthetascs	left mandible rightmandible lacinia lacinia mobilis mobilis	pereopod 6 propodus leaf-like setae	pleopod basis outer/ inner setae	pleopod endopod inner setae	uropod endopod articles
Z. shitipingensis sp. nov.	3	wide, narrow crenulated	6	3–8/1	1	5–6
Z. amiti	4	small, minute rounded	5	4/0	1	6
Z. andaminimus	2	narrow minute	7	3–5/1	1	4
Z. angua	1	wide, small crenulated	6	5/1	2	5
Z. belli	4	pointed not articulated	~9	6/1	1	5–6
Z. beringi	3	wide, narrow crenulated	NA	NA	NA	5
Z. cloacarattus	3	triangular scale-like	6	4/1	1	5
Z. coralensis	3	wide, narrow crenulated	11	6/1	1	3
Z. coturnix	2	small, not articulated triangular	10	4–6/1	1	4
Z. edgari	3–4	large, narrow crenulated	6	5–6/1	2–4	5–6
Z. exsargasso	3	one-denticled not articulated	10	5/1–2	1	4–5
Z. fresii	3	wide, narrow crenulated	4	3/1	2	3
Z. holdichi	3	rectangular narrow	6	5/1	2–3	4–5
Z. kirkmani	2–4	pointed not articulated	12	6/1	3	5
Z. koreaensis	3	wide, minute, crenulated bilobed	6	5/1	2	4–5
Z. kurilensis	1	wide, narrow crenulated	6	5/1	1	3–4
Z. marmoratus	1	NA NA	6	NA	NA	5–7
Z. mooneyi	3–4	wide, narrow, small crenulated	7	~9/1	1	3
Z. nannioggae	1	narrow, not articulated bilobed	6	3–4/0	1	4
Z. normani	3	wide, narrow crenulated	6	6/1	3	5
Z. novaezealandiae	3	linguiform minute, pointed	8–20	7–13/1–5	4–8	4–5
Z. odohertyae	3–4	pointed not articulated	10	~9/1	5–6	6
Z. phytalensis	4	wide, narrow crenulated	8	4/1	1	3
Z. russi	3–4	rounded not articulated	7	4–7/1	1	5–6
Z. seurati	2	linguiform not articulated	9	6/1	1	5