Phoxokalliapseudes aculeatus, Wi, Jin Hee, Kang, Chang-Keun & Soh, Ho Young, 2017

Wi, Jin Hee, Kang, Chang-Keun & Soh, Ho Young, 2017, Two new species in the genus Phoxokalliapseudes Drumm & Heard, 2011 (Crustacea: Tanaidacea: Kalliapseudidae) from the southwestern and southern coasts of Korea, Zootaxa 4231 (3), pp. 341-363 : 342-351

Phoxokalliapseudes aculeatus n. sp.

( Figs 1–6 )

Materials examined. Holotype: (NIBRIV0000634754), female dissected and mounted on six slides; collected from the western coast of Korea (34˚19´27.76´´N; 126˚ 48´8.29´´E, at a depth of 1 m) in September 2015.

Allotype: (NIBRIV0000634916), male dissected and mounted on five slides; from the same locality as the holotype.

Paratypes: one female partly dissected on one slide (NIBRIV0000634755) and deposited in one vial (NIBRIV0000634915) from the same locality as the holotype. One male partly dissected on one microslide (NIBRIV0000634917) and deposited in one vial (NIBRIV0000634918) from the same locality as the holotype.

Diagnosis. Rostrum rounded. Pereonites 2–6 each with hyposphaenium. Pleonites 1–5 with ventral process. Pleotelson with two long plumose setae on indented tip. Antennule with six-articled accessory flagellum. Antenna first article with seven distal plumose setae on medial extension. Cheliped basis with two strong spiniform setae on ventral margin. Pereopod 6 dactylus with one simple seta on sub-proximal margin. Female pereopod 6 dactylus 2.6 times as long as propodus. Male pereopod 6 dactylus 4.4 times as long as propodus.

Etymology. The specific name is derived from the Latin adjective aculeatus , ‘prickly’ or ‘having spines’, referring to the two robust spines on the ventral margin of the cheliped basis of both sexes.

Description of female. Ovigerous. Body ( Fig. 1 A, B): dorsoventrally flattened, holotype 8.4 mm long, 5.4 times as long as wide. Cephalothorax as long as wide, rostrum rounded. Pereon ( Fig. 1 A, B): 51.3% of body length. Pereonites 2–6 each with hyposphaenium. Pereonite 1 not fused to cephalothorax, 0.4 times as long as cephalothorax, 0.4 times as long as wide, proximolateral margin wider than cephalothorax, with three slender setae. Pereonite 2 slightly longer than pereonite 1, lateral margin rounded, with setae. Pereonite 3 1.3 times as long as pereonite 2, 0.6 times as long as wide. Pereonite 4 1.2 times as long as pereonite 3, 0.7 times as long as wide.

Pereonite 5 slightly shorter than pereonite 4, 0.6 times as long as wide. Pereonite 6 0.7 times as long as pereonite 5, 0.3 times as long as wide. Pleonites 1–5 ( Fig. 1 A, B): 20 % of body length, rounded epimera with several plumose setae and fine setules along lateral margin. All pleonites with ventral process ( Fig. 1 B). Pleonite 5 with distolateral extension. Pleotelson ( Fig. 1 A, B): distally tapered, 13.5 % of body length, 0.7 times as long as pleon, slightly wider than long, with several simple setae along lateral to distal margin and two distal plumose setae.

Antennule ( Fig. 1 C): proximal peduncle article robust, half of total length, 2.3 times as long as maximum width, with two ventral spiniform setae (arrowed), several broom setae and simple setae along outer and inner margins. Second peduncle article 0.3 times as long as proximal article, 1.4 times as long as wide, with several simple setae. Article 3 half as long as article 2, with two simple setae distally. Article 4 0.7 times as long as article 3. Outer flagellum longer than proximal peduncle article 1, with eleven articles, one aesthetasc on articles 5 and 6. Inner flagellum with six articles, three simple setae and broom seta on terminal article.

Antenna ( Fig. 1 D): article 1 with long medial extension, with seven plumose setae on distal extremity and one plumose seta on outer subdistal corner. Article 2 ornamented with microtrichia and squama with four plumose setae. Article 3 with two distomedial plumose setae. Article 4 slightly shorter than articles 5–10 combined, with two rows of plumose setae along inner margin and plumose seta on outer margin. Articles 5–10 bearing several simple setae and broom setae.

Labrum ( Fig. 2 A): distal margin rounded, with numerous setules. Clypeus with four hook-like cusps.

Mandibles ( Figs. 2 B–F). Left mandible ( Fig. 2 B, C): incisor distally with twelve small denticles. Lacinia mobilis smaller than incisor, with ten small denticles. Setiferous lobe with five serrated spiniform setae ( Fig. 2 C). Molar process with several pointed teeth along distal margin. Palp covered with rows of microtrichia, with about 30–32 long plumose setae on inner margin and a short terminal spiniform seta. Right mandible ( Fig. 2 D–F): incisor with two denticles of different size, of which inner one much bigger. Molar process with five folds of feather-like ornamentations, terminally setulate setae, and small spines along distal margin ( Fig. 2 F). Setiferous lobe and palp similar to that of left mandible.

Labium ( Fig. 2 G): palp sub-rectangular shape, 1.3 times as long as wide, with small spine on inner distal corner, covered with setules on entire surface.

Maxillule ( Fig. 2 H): inner endite with four setulose setae of different length on distal margin and microtrichia along inner and outer margins. Outer endite with ten setulose setae on distal margin, two setulose setae on subdistal margin, and rows of setules along outer margin; outer distal margin with sunken area (arrowed).

Maxilla ( Fig. 2 I): outer lobe of movable endite with five setulose setae; inner lobe of movable endite with patch of spinules and 17 distally blunt spiniform setae. Inner lobe of fixed endite with distal row of five serrate spiniform setae, proximal row of setulose setae, and subdistal five setulose setae. Outer lobe of fixed endite with four serrate spiniform setae, five setulose setae, and seven simple setae along distal margin. Outer margin with some spinous spines and microtrichia.

Maxilliped ( Fig. 3 A, B)): basis fringed with plumose setae along outer margin and several rows of setules along inner margin. Palp article 1 with four setae on inner margin and one short seta on outer subdistal margin. Palp article 2 with two rows of long plumose setae along inner margin and four setae on outer distal margin (arrowed). Palp articles 3 and 4 with two rows of plumose setae along inner margin. Endite ( Fig. 3 B) with six setulose setae on distal margin, eight setulose setae on inner fold, and two coupling hooks on inner margin. Epignath not examined.

Cheliped ( Fig. 3 C): basis 1.7 times as long as wide, with two strong spiniform setae (arrowed) and five simple setae on ventral margin. Merus 1.2 times as long as wide, with simple seta on ventromedial margin, two simple setae on ventrodistal margin, nine spinose spines on distal margin, dorsodistal corner protruded. Carpus about three times as long as wide, with two rows of setae along inner margin and four setae on distal and subdistal dorsal margin. Propodus robust, 1.6 times as long as wide, with row of setae on proximal margin, five setae near insertion of dactylus. Dactylus with one group of three long setae on mid region, seven simple setae along dorsal margin, and 14 teeth along cutting edge. Fixed finger with three simple setae along ventral margin, several simple setae, setules, and spinose spines along cutting edge, and ten simple setae on proximal margin. Exopodite with three articles and distal article bearing two long plumose setae.

Pereopod 1 ( Fig. 3 D): basis 1.9 times as long as wide, with two broom setae and one short simple seta on dorsal margin, five simple setae and one spiniform setae on ventral margin. Ischium with two simple setae of unequal length on ventral margin. Merus 0.8 times as long as basis, 1.6 times as long as wide, with ten simple setae and robust spiniform seta on ventral margin and spiniform seta and simple seta on dorsodistal margin. Carpus half as long as merus, slightly shorter than wide, with several simple setae and two robust spiniform setae on ventral margin, several scale-like processes on dorsodistal margin, three short spiniform setae on mid-region, and nine simple setae and spiniform seta on dorsal margin. Propodus shorter than carpus, ventral margin with several simple setae and seven spiniform setae, broom seta, simple seta at basis of dactylus, three simple setae on mid-region, and several small processes; dorsal margin with two spines of unequal length and four simple setae. Dactylus represented by sensory organ, shorter than propodus, with several long sensory setae and one simple seta. Exopodite with two distal setulose setae.

Pereopod 2 ( Fig. 4 A): basis 2.4 times as long as wide, with two broom setae and five simple setae on ventral margin. Ischium with three simple setae on ventrodistal margin. Merus 0.4 times as long as basis, with spiniform seta and two simple setae on ventro-subdistal margin and two dorsodistal small simple setae. Carpus as long as merus, 1.7 times as long as wide, with three serrated spiniform setae and four simple setae on ventral margin, two spiniform setae on subdistal margin, and three simple setae on dorsodistal margin. Propodus 0.9 times as long as carpus, almost twice as long as wide, with five spiniform setae and five simple setae on ventral margin, five spiniform setae, one setulose seta, and two simple setae on distal margin, and three spiniform setae bearing two strong protrusions at both sides of base (arrowed) and broom seta on mid-dorsal margin. Dactylus and unguis combined 2.1 times as long as propodus. Dactylus lacking sensory lobe. Unguis 2.7 times as long as dactylus.

Pereopod 3 ( Fig. 4 B): basis 2.5 times as long as wide, with broom seta on dorsal margin and two simple setae on ventrodistal margin. Ischium and merus similar to those of pereopod 2. Carpus 0.8 times shorter than merus, with four spiniform setae and simple seta on dorsodistal and subdistal margins and three spiniform setae and simple seta on ventral margin. Propodus with five spiniform setae on subdistal margin, two short distal spiniform setae with basal protrusions on dorsodistal margin and broom seta on dorsomedial margin, and six spiniform setae and six simple setae on ventral margin. Dactylus and unguis combined similar to that of pereopod 2. Dactylus lacking sensory lobe. Unguis 2.9 times as long as dactylus.

Pereopod 4 ( Fig. 4 C): basis 2.2 times as long as wide, with three simple setae on dorsal margin. Ischium similar to that of pereopod 2. Merus with three simple setae and two spiniform setae on ventrodistal margin. Carpus about 1.3 times as long as merus, with two rows of six spiniform setae and simple setae along ventral margin. Propodus slightly shorter than carpus, dorsal margin with proximal broom seta and six distal spiniform setae bearing two basal processes on dorsal margin, two rows of spiniform setae from mid-ventral to distal margin and four simple setae on ventral margin. Dactylus about half as long as propodus, with nine distal simple setae.

Pereopod 5 ( Fig. 4 D, E): basis 2.4 times as long as wide, with two broom setae and two simple setae on dorsal margin. Merus with two spiniform setae and two simple setae on ventrodistal margin. Carpus with two rows of six spiniform setae and several simple setae on ventral margin. Propodus with two rows of nine spiniform setae and several simple setae and six short spiniform setae with basal processes (arrowed in Fig. 4 E) and broom setae on dorsal margin.

Pereopod 6 ( Fig. 4 F): basis with one dorsal broom seta and five long plumose setae along dorsal and ventral margins. Ischium with three ventral simple setae. Merus 1.4 times as long as ischium, with three simple setae on ventral margin and two plumose setae on dorsal margin. Carpus 3.1 times as long as merus, with six plumose setae on dorsal margin and five simple setae on ventral margin. Propodus 0.6 times as long as carpus, with five spiniform setae and row of 23 short setulose setae along ventral margin and one distal comb-like spine. Dactylus 2.6 times as long as propodus, naked.

Pleopod ( Fig. 3 E, F): basal article with three or four plumose setae on distal margin and setules along inner distal margin. Exopodite with 20 plumose setae each on outer and inner margin. Endopodite with 22 plumose setae and setules along inner margin; distal region of innermost seta with one wrinkled spiniform setae and three simple setae (arrowed in Fig. 3 F).

Uropod ( Figs. 1 A, 6G): basal article 2.7 times as long as wide, with three simple setae on distal and subdistal margin, not reached to distal margin of pleotelson ( Fig. 1 A). Exopodite with three articles. Article 1 with one distal seta. Article 2 2.9 times as long as article 1. Article 3 1.3 times as long as article 2, with five distal setae. Endopodite with 20 articles, with several setae and broom setae.

Description of male. Very similar to female except for following differences: Body ( Fig. 5 A): 8.7 mm long, 5.1 times as long as wide. Cephalothorax 16 % of body length, slightly wider than long, with simple seta on each mid-lateral margin. Pereon: pereonite each with different shape, with ventral spine and spinule, 46 % of body length. Pereonite 1 0.3 times as long as wide, maximum width at proximal region, with three setae on proximolateral margin and two simple setae on distolateral margin. Pereonite 2 subequal length and width of pereonite 1, maximum width at mid-region, with four setae on proximolateral margin and two distolateral setae. Pereonites 1 and 2 0.8 times as long as cephalothorax. Pereonite 3 1.3 times as long as pereonite 2, half as long as wide, with three setae on proximolateral margin, and two distolateral setae. Pereonite 4 slightly longer than pereonite 3, 0.6 times as long as wide, maximum width at distolateral region, with two setae on proximolateral margin, two mid-lateral setae, and short distolateral seta. Pereonite 5 slightly shorter than pereonite 4, setal number and shape similar to pereonite 4. Pereonite 6 shortest, 0.3 times as long as wide, with proximolateral seta, four short setae on mid to distolateral margin, and maximum width at distolateral region. Pleon: 25% of body length, 1.3 times as long as wide. Pleotelson: half as long as pleon, 0.8 times as long as wide, narrowed from three fifth to distal margin, with seta on mid-lateral margin and two plumose setae distally.

Antennule ( Fig. 5 B, C): first peduncle article 2.4 times as long as wide, with several broom setae and simple setae along inner and outer margins. Second peduncle article 1.2 times as long as wide, with three broom setae on outer margin and three simple setae on inner margin. Article 3 0.8 times as long as wide, with outer seta and two inner setae. Outer flagellum 1.1 times as long as proximal peduncle article, with twelve articles, articles 1–6 with bundle of aesthetascs, decreasing in number, and two simple setae on distal margin. Article 7 with three aesthetascs and two simple setae on distal margin. Article 8 with one aesthetasc and two simple setae on distal margin. Article 9 with aesthetasc and three simple setae on distal margin. Article 10 naked. Article 11 with two distal simple setae. Article 12 1.6 times as long as article 11, with four simple setae and broom seta on distal margin. Inner flagellum with 5 articles. Articles 1–4 with simple seta on distal outer margin. Article 5 1.2 times as long as article 4, with four simple setae and broom seta terminally.

Left mandible ( Fig. 5 D): setiferous lobe with six serrated setae (arrowed)

Right mandible ( Fig. 5 E, F): inner denticle of incisor bifurcated distally (arrowed in Fig. 5 F), setiferous lobe with six serrated setae.

Maxilla ( Fig. 5 G): outer lobe of movable endite with three setulose setae (arrowed). Inner lobe of fixed finger with setulose seta and row of slender setae.

Cheliped ( Fig. 6 A–D): basis slightly wider than long, with two spiniform setae, smaller compared to that of female. Merus 0.6 times as long as basis, ventrodistal margin protruded upwardly, with three simple setae and row of small protrusions and short seta on mid-ventral region. Carpus 2.6 times as long as merus, 2.3 times as long as wide. Propodus 1.3 times as long as carpus, 1.3 times as long as wide. Cutting edge of fixed finger with two large denticles proximally and several setae between unguis and distal denticle. Dactylus longer than fixed finger, with several curved spiniform setae along cutting edge and several simple setae on outer surface.

Pereopod 6 ( Fig. 6 E): basis 3.6 times as long as wide, with six plumose setae along dorsal margin and six simple setae along ventral margin. Ischium with three ventral simple setae. Merus 1.5 times as long as wide, with two simple setae on ventral margin and three plumose setae along dorsal margin. Carpus 2.5 times as long as merus, 2.1 times as long as wide, with five simple setae along ventral margin and six plumose setae along dorsal margin. Propodus 0.7 times as long as carpus, with four spiniform setae, row of 26 short setulose setae, and one distal blunt spiniform seta on ventral margin. Dactylus distally tapered, 4.4 time as long as propodus.

Uropod ( Fig. 6 F): longer than that of female. Basal article 2.3 times as long as wide, with two simple setae on distal margin, extending over distal margin of pleotelson. Endopodite with 23 articles.

Remarks. Phoxokalliapseudes aculeatus n. sp. shows morphological features typical of the genus Phoxokalliapseudes , which is characterized by a labrum with cusps in both sexes, the male’s cheliped with a robust denticle on the inner surface of the propodus near the insertion of the dactylus ( Fig. 6 A), and the pereopod 6 dactylus in males is substantially longer than the propodus (over four times as long). Phoxokalliapseudes aculeatus is closely related to P. tomiokaensis ( Shiino, 1966) but distinguished by the absence of a sensory proximal lobe on the dactylus of pereopods 2 and 3 (which only exist in P. multiarticulus and P. singaporensis within the genus), and the length-to-width ratio of the pleotelson of both sexes. However, P. aculeatus can be discriminated from P. tomiokaensis using the following morphological characteristics: in both sexes, 1) article 5 of the antenna is shorter than the second article, which is longer in P. tomiokaensis ; 2) the length-to-width ratio of the cheliped propodus is smaller (see Table 1). In the female, 3) pereonites 2–6 each have a hyposphaenium and a small spinule; 4) the cheliped basis has two curved spines on the ventral margin, but no spines in P. tomiokaensis . In the male, 5) the ratio of the lengths of the dactylus to the propodus of pereopod 6 is substantially larger (4.4: 1) than that of P. tomiokaensis (2.7: 1).

To date, sexual dimorphism has been examined for the cheliped and antenna, but in this study, sexual dimorphism was examined for morphological characteristics such as the mouthparts, and it presents in the shape of the inner denticles of the incisor of the right mandible (distally pointed in the female and distally bifurcate in the male). A morphological combination of the long dactylus of pereopod 6 and pereopods 2 and 3 without a sensory lobe on the dactylus corresponds to the P. gobinae male. However, the square-like denticle on the cutting edge of the fixed finger and the number of ventral spines of the basis (zero in the female and one in the male) in the cheliped differed from P. aculeatus .

Figures

FIGURE 1. Phoxokalliapseudes aculeatus n. sp. female holotype. A, habitus, dorsal view; B, habitus, lateral view; C, antennule; D, antenna. Scale bars are given in mm.

FIGURE 2. Phoxokalliapseudes aculeatus n. sp. female holotype. A, labrum; B, left mandible; C, incisor, lacinia mobilis, and setiferous lobe of left mandible; D, right mandible; E, incisor of right mandible; F, molar process of right mandible; G, labium, palp; H, maxillule; I, maxilla. Scale bars are given in mm.

FIGURE 3. Phoxokalliapseudes aculeatus n. sp. female holotype. A, maxilliped; B, endite of maxilliped; C, cheliped; D, pereopod 1; E, pleopod; F, detailed view of proximal pleopod endopod seta. Scale bars are given in mm.

FIGURE 4. Phoxokalliapseudes aculeatus n. sp. female holotype. A, pereopod 2; B, pereopod 3; C, pereopod 4; D, pereopod 5; E, distal part of pereopod 5 propodus; F, pereopod 6. Scale bars are given in mm.

FIGURE 5. Phoxokalliapseudes aculeatus n. sp. male allotype. A, habitus, dorsal view; B, antennule, C, distal part of antennule (black circle indicates 6 th article of outer flagellum); D, incisor, lacinia mobilis, and setiferous lobe of left mandible; E, right mandible, F, incisor, and setiferous lobe of right mandible; G, maxilla. Scale bars are given in mm.

FIGURE 6. Phoxokalliapseudes aculeatus n. sp. male allotype. A, cheliped; B, fixed finger of cheliped; C, ventrodistal part of cheliped merus; D, male paratype, cheliped chela; E, male allotype, pereopod 6; F, uropod; G, female holotype, uropod. Scale bars are given in mm.