Pseudoapseudomorpha tagopilosus, Tzeng, You-Wei & Hsueh, Pan-Wen, 2014

Tzeng, You-Wei & Hsueh, Pan-Wen, 2014, New species and records of Apseudomorpha (Crustacea: Tanaidacea) from Taiwan, Zootaxa 3869 (3), pp. 313-337 : 321-327

Pseudoapseudomorpha tagopilosus sp. nov.

Figs 4–7

Material examined. Holotype: female ( NMNS 7340-1), 2.3 mm, Jihuei (23°06'54.9"N, 121°24'16.3"E), eastern Taiwan, intertidal, washing from red alga Jania sp., collected by You-Wei Tzeng, August 18, 2012.

Allotype: male ( NMNS 7340-2), 1.9 mm, same collection data as holotype.

Paratypes: one female ( NMNS 7340-3), 1.5 mm and three males ( NMNS 7340-5), Jialulan (22°48'10.2"N, 121°11'57.0"E), eastern Taiwan, intertidal, washing from red alga Mastophora sp., collected by You-Wei Tzeng, April 20, 2012; one post-ovigerous female and two males ( NMNS 7340-4), same collection data as holotype.

Diagnosis. Female: Pleonites 2, 3 and 4 with one long lateral plumose seta. Antennule with four-segmented outer flagellum and three-segmented inner flagellum. Antenna peduncle article 1 inner expansion ovate, denticulate; flagellum three-segmented. Maxillule palp article 2 with five setae. Cheliped exopod article 3 with six distal plumose setae. Pereopods 1–2 propodus with six ventral spines. Pereopod 4 carpus with ten ventral spines. Pleopod absent. Uropod with five-segmented exopod and eight-segmented endopod.

Description. Holotype: Habitus ( Fig. 4 A) body dorsoventrally flattened, about five times as long as wide. Cephalothorax about 0.25 times as long as body, with well-separated eye-lobes; rostrum ( Fig. 4 B) acute, covered by many tubercles; carapace dorsal surface with several grooves and paired lateral plumose setae. Pereon with all pereonites much shorter than broad; pereonites 1 and 2 shortest and widest, without lateral projections, with two dorsal plumose setae and two pairs of lateral plumose setae; pereonite 3 longer and narrower than pereonite 2, with two dorsal and two pairs of lateral plumose setae; pereonites 4–5 with one lateral blunt projection, two dorsal and three pairs of lateral plumose setae; pereonite 6 narrowest, with one lateral blunt projection, two dorsal and six paired lateral plumose setae. Pleon ( Fig. 4 C) short, about 0.15 times as long as body; pleonite 1 naked; pleonite 2 laterally pointed, with two dorsal and one paired lateral long plumose setae; pleonites 3–4 laterally pointed, with one paired lateral long plumose seta; pleonite 5 with one paired lateral short plumose setae. Pleotelson with four dorsal plumose setae, terminally pointed, with one apophysis ( Fig. 7 G).

Antennule ( Fig. 4 D) about 1.4 times as long as cephalothorax; peduncle article 1 almost 0.5 times as long as antennule, outer margin with one pointed apophysis, three plumose setae, and clusters of broom setae and setules, inner margin with five pointed apophyses and seven plumose setae, distal margin with inner and outer pointed apophyses; article 2 a quarter as long as first article, outer margin with cluster of broom setae and setules, inner margin with two plumose setae and one distal apophysis; article 3 as long as article 2, with one outer distal plumose seta and four inner plumose setae; article 4 with two inner plumose setae and one simple distal seta; outer flagellum four-segmented, segment 1 with one distal plumose and simple seta, segment 2 with one aesthetasc and three plumose and four simple distal setae, segment 3 with one aesthetasc and three distal setae, segment 4 with one aesthetasc and five distal setae; inner flagellum three-segmented, about 0.5 times as long as outer flagellum, segment 1 with two distal plumose setae, segment 2 with two distal plumose and one simple setae, segment 3 with five distal setae.

Antenna ( Fig. 4 E) over 0.5 times as long as antennule; peduncle five-articled, article 1 inner expansion large and ovate, with many small teeth on inner margin, article 2 longest, 2.5 times as long as wide, with four outer broom setae, two large and three small inner pointed apophyses, one large distal apophysis, and three inner plumose setae, several setules, squama present, with two distal plumose setae, article 3 short, with one large and one short inner distal plumose setae, article 4 about 0.5 times as long as article 2, with four plumose setae and many setules, article 5 as long as article 4, with one inner plumose setae, two strong distal plumose setae, five broom setae and several setules; flagellum three-segmented, segment 1 slightly longer than the peduncle article 3 but narrower than that, with one distal broom seta and five simple setae, segment 2 as long as preceding segment, with one distal broom seta and two simple setae, distal segment with six distal setae.

Right mandible ( Fig. 4 F) incisor without serrations, setal row with one bifurcate seta and three trifurcate setae; palp three-articled, article 1 shortest, with one plumose seta, article 2 about 2.5 times as long as first article, with ten simple setae and seven pinnate setae, article 3 slightly shorter than the preceding article, with one row of six pinnate setae on inner margin, and one plumose and four simple distal setae. Left mandible with strong lacinia mobilis ( Fig. 4 G), setal row with three multifurcate setae; palp similar to right mandible. Labium ( Fig. 4 H) palp covered by setules, with two distal spines; lobe with setules on inner margin. Maxillule ( Fig. 4 I) palp two-articled, with five setae; outer endite with eleven distal spines and with setules on outer margin; inner endite with four distal plumose setae. Maxilla ( Fig. 5 A) outer margin covered by setules; movable endite outer margin with one fine denticle and several setules; movable endite outer lobe with four distal and two subdistal setae, inner lobe with eight distal setae; fixed endite outer lobe with five trifurcate spiniform setae, four pinnate setae and one simple seta, and four fine denticles, inner lobe with one row of 25 setae and four distal pinnate setae. Maxilliped basis ( Fig. 5 B) inner margin with one plumose setae; endite ( Fig. 5 C) outer margin with setules, inner margin with 18 setae, distal margin with three bifurcate spiniform setae, two long plumose setae, and three simple setae; palp ( Fig. 5 B) article 1 inner margin with two simple setae; article 2 inner margin with six simple setae and one plumose seta, outer distal corner with one strong spine; article 3 with eight inner setae; article 4 with nine distal setae. Epignath ( Fig. 5 D) cup-shaped, covered by setules, and with one long distal setulate seta.

Cheliped ( Fig. 5 E–F) exopod three-articled, article 1 small and naked; article 2 dorsal margin with three teeth, article 3 with six distal plumose setae, dorsal margin with five teeth; basis short, about 1.3 times as long as wide, ventral margin with one median spine and four distal plumose setae; merus ventral margin with one apophysis and four plumose setae; carpus 1.8 times as long as wide, with two distodorsal and two distoventral plumose setae; propodus (including fixed finger) 1.3 times as long as carpus, about twice as long as wide, fixed finger outer margin with six setae, incisive margin with five setae; dactylus about 0.5 times as long as propodus.

Pereopods 1–4 with oostegite. Pereopod 1 ( Fig. 6 C) coxa with blunt apophysis and three plumose setae; basis with two broom, three plumose dorsal setae, and one distoventral plumose seta; ischium with one distoventral plumose seta; merus with cluster of three dorsal plumose setae and one distodorsal spine, ventral margin with two plumose setae and two distal spines; carpus with three dorsal plumose setae, one ventral plumose seta and two rows of ventral spines (lateral row with five spines and marginal row with four spines); propodus ( Fig. 6 D) with one dorsal broom seta, one long distodorsal simple seta, one distoventral simple seta, six medial pinnate setae, and two rows of spines (dorsal row with three spines and one large serrated spine, ventral row with six spines); dactylus with two dorsal setae, one ventral seta and denticle. Pereopod 2 ( Fig. 6 E) similar to pereopod 1 but coxa with one plumose seta, basis with three ventral plumose setae, merus dorsal margin with one plumose seta and setules, carpus with five dorsal plumose setae, and propodus ( Fig. 6 F) with three medial pinnate setae. Pereopod 3 ( Fig. 6 G) similar to pereopod 1 but coxa with one plumose seta, merus with one dorsal plumose seta, three ventral spines and four ventral plumose setae and without distodorsal spines, carpus marginal row with three spines, propodus with one medial pinnate seta, ventral margin with five spines.

Pereopod 4 ( Fig. 7 A) coxa with one plumose seta, without apophyses; basis dorsal margin with three broom setae, one plumose setae, and with one distoventral plumose seta; ischium with one distoventral plumose seta; merus with one dorsal plumose seta, two ventral plumose setae and two ventral spines; carpus ( Fig. 7 B) with five distal plumose setae and two rows of ventral spines (marginal row with six spines, medial row with four spines); propodus with one dorsal broom seta, eight distal pinnate setae, and four ventral spines; dactylus with one dorsal seta, one ventral seta and one denticle. Pereopod 5 ( Fig. 7 C) coxa with one plumose seta; basis with dorsal cluster of four broom setae, one dorsal plumose seta, and four ventral plumose setae; ischium with one distoventral plumose seta; merus with one dorsal and two ventral plumose setae; carpus slightly longer than carpus of pereopods 1–4, with one distodorsal and one distoventral plumose setae; propodus remarkably longer than propodus of pereopods 3–4, with two distal plumose setae, two distal pinnate setae and four ventral spines; dactylus more straight comparing to dactylus of pereopods 1–4, with two dorsal setae, one ventral seta and one denticle. Pereopod 6 ( Fig. 7 D) relatively similar to pereopod 5 but basis with three broom setae, two plumose dorsal setae, and six ventral plumose setae; merus with two distoventral setae, carpus slightly longer than carpus of pereopod 5, propodus with one dorsal broom seta, one long simple seta, six distal pinnate setae, and three ventral spines.

Pleopods absent.

Uropod ( Fig. 7 G) about 1.5 times as long as pleon; basal article with two lateral and two distal plumose setae; exopod with five segments, each segment with one to three distal plumose setae; endopod eight-segmented, segments 1–7 with one to three distal plumose setae, distal segment with five plumose and two broom distal setae.

Male allotype: Similar to female but with unequal chelipeds. Left cheliped ( Fig. 6 A) more robust than female cheliped, with basis as long as wide, carpus 1.5 times as long as wide, and palm 1.4 times as long as wide. Right cheliped ( Fig. 6 B) smaller and thinner than female cheliped, with carpus 2.5 times as long as wide, and palm 1.2 times as long as wide. Pleopods uniramous, present only on last three pleonites; first pair ( Fig. 7 E) very short, twoarticled; last two pairs ( Fig. 7 F) long and slender, two-articled, with one distal plumose seta.

Etymology. The name is derived from the Latin “ tago ” (palp) and “ pilosus ” (hairy), referring to the palp of the mandible covered by many setae.

Type locality. Jihuei, eastern Taiwan.

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

Remarks. According to the key given by Guţu (2009), the Pseudoapseudomorpha tagopilosus sp. nov. is most similar to Pseudoapseudomorpha ornata , which is also the geographically nearest species (recorded from Malaysia). Both species share: 1) presence of one long lateral seta on pleonites 2–3, 2) pleopods only on pleonites 3–5 in the male but absent in the female, and 3) presence of teeth on the dorsal margin of the cheliped exopod ( Guţu 2006: Figs 354–376; present study: Figs 4–7 , Table 2). However, the new species can be distinguished from P. ornata by having one long lateral seta on pleonite 4, a four-segmented antennule outer flagellum, five setae on the maxillule palp article 2, six distal plumose setae on the cheliped exopod, six ventral spines on the propodus of pereopod 1, six marginal and four medial spines on the ventral margin of pereopod 4 carpus, and the male with a vestigial pleopod (only on pleonite 3). Moreover, the small cheliped of the male of P. tagopilosus is smaller and thinner than the female’s cheliped, compared to the similar size of the same cheliped forms in P. ornata ( Guţu 2006: Figs 354–376; present study: Figs 4–7 , Table 2).

Figures

FIGURE 4. Pseudoapseudomorpha tagopilosus sp. nov. Holotype (NMNS 7340 - 1) female: A body dorsal view; B rostrum; C pleon; D right antennule; E right antenna; F right mandible; G left mandible lacinia mobilis and setal row; H labium; I left maxillule. Scale: A, 1 mm; B – F, H – I, 0.1 mm; G, 0.5 mm.

FIGURE 5. Pseudoapseudomorpha tagopilosus sp. nov. Holotype (NMNS 7340 - 1) female: A maxilla; B left maxilliped; C left maxilliped endite; D epignath; E right cheliped; F left cheliped exopod. Scale: A – F, 0.1 mm.

FIGURE 6. Pseudoapseudomorpha tagopilosus sp. nov. Allotype (NMNS 7340 - 2) male: A left cheliped; B right cheliped. Holotype (NMNS 7340 - 1) female: C right pereopod 1; D right pereopod 1 propodus and dactylus medial view; E right pereopod 2; F right pereopod 2 propodus and dactylus medial view; G right pereopod 3. Scale: A – G, 0.1 mm.

FIGURE 7. Pseudoapseudomorpha tagopilosus sp. nov. Holotype (NMNS 7340 - 1): A right pereopod 4; B right pereopod 4 carpus medial view; C right pereopod 5; D right pereopod 6; E left pleopod 3; F left pleopod 5; G right uropod. Scale: A – G, 0.1 mm.