Joeropsis brevicornis Koehler, 1885 by original designation.

Body smooth, rarely with sculpture dorsally, laterally parallel. Pseudorostrum with overhanging apex. Eyes positioned dorsolaterally. Mandibles with evenly spaced cusps; spine row consisting of long setae. Maxilliped, endite reaching end of palp article 3; palp article 3 lacking medial lobe. Pereopod 1 with 2 claws and pereopods 2–7 with 2 or 3 claws. Pleopod 2 with a few short simple setae distally in females. Pleopod 3, exopod obliquely articulated between articles (Just 2001; Bruce 2015).

The genus Joeropsis can be differed from other joeropsidid genera by having a dorsally smooth or finely granular body (vs. coarsely granular and nodular in Rugojoeropsis Just, 2001) and parallel lateral body shape (vs. converging posteriorly in Scaphojoeropsis Just, 2001) (Bruce 2015). The colour pattern of a body can be distinguishable to easily separate members of the genus (Bruce 2015). Additionally, the morphology of the cephalon, pseudorostrum, antennae, maxilliped, pleotelson, and male pleopod 1 can be the most diagnostic characters for Joeropsis species (Kensley and Schotte 2002; Bruce 2009, 2015).

Holotype, designated here: South Korea • 1 ♂ (5.0 mm); Jeju-do, Jeju-si, Chuja-myeon, Chujado Island; 33°55'18"N, 126°19'27"E; 20 m; 17 Apr. 2019; Smith-McIntyre grab; NIBRIV0000862803.

Paratypes : 2 ♂♂ (4.2, 4.8 mm), 3 ♀♀ (3.6, 3.8, 3.8 mm); same data as for holotype; NIBRIV0000896084.

South Korea • 1 ♂; Jeju-do, Jeju-si, Udo-myeon, Udo Island; 33°31'38"N, 126°57'14"E; 17 Apr. 2019; 15 m; Smith-McIntyre grab • 5 ♂♂, 4 ♀♀; Jeju-do, Seoqwipo-si, Daejeong-eup; 33°11'24"N, 126°16'08"E; 31 Jan. 2018; 30 m; Smith-Mclntyre grab; NIBRIV0000862803 • 1 ♂; Jeollanam-do, Sinan-gun, Jangsan-myeon, Baegyado Island; 34°22'24"N, 126°00'15"E; 12 Apr. 2018; 10 m; SCUBA diving • 1 ♂; Jeollanam-do, Yeosu-si, Samsan-myeon, Sangbaeckdo Island; 34°03'15"N, 127°35'00"E; 15 m; 28 Jun. 2017; SCUBA diving.

The specific name, denticulatus, is derived from the Latin word denticulatus, meaning “with small teeth”. This name refers to pereopods possessing serrate cuticular scales.

Body (Figs 2A, 3A) almost 3.9 × longer than width; dorsal surface matte, smooth, without setae. Cephalon 0.7 × as long as wide; lateral margins narrowing anteriorly; eyes positioned sublaterally, globular, dark brown, dorsally bulging. Pseudorostrum (Fig. 3B) 0.7 × as long as proximal wide, narrowing anteriorly; apex rounded. Pereonites not compact; lateral margins smooth. Pleotelson ~ 1.0 × longer than greatest width, shield-shaped, tapering distally; caudomedial lobe subacute, tapering distally; lateral margins slightly convex, with 8 spines.

Figure 2. 

Photographs of two new species of Joeropsis: A J. denticulatus sp. nov., one of paratypes (NIBRIV0000896084), dorsal view B J. semicircularis sp. nov., one of paratypes (NIBRIV0000896085), dorsal view. Scale bars: 10 mm (A); 5 mm (B).

Figure 3. 

Joeropsis denticulatus sp. nov., holotype, male A habitus, dorsal view B pseudorostrum C antennula D antenna E detail of peduncular articles 5 to flagellar article 1 F left mandible G right mandible H maxillula I maxilla J maxilliped K detail of maxillipedal palp. Scale bars: 1 mm (A); 0.2 mm (C, D, F–J); 0.1 mm (E, K); 0.05 mm (B).

Antennula (Fig. 3C), peduncular article 1 rectangular, 1.4 × longer than width, with serrate cuticular scales distally, 5 simple setae along with lateral margin, 1 penicillate seta distally, and 5 penicillate setae medially; article 2 oblong, 0.5 × as long as article 1, with 1 simple seta and 2 penicillate setae distally, and cuticular scales laterally; article 3 oblong, 0.6 × as long as article 2, with 2 simple setae laterally and 3 simple setae distally; flagellar article 1 almost 0.5 × as long as peduncular article 3, with 1 penicillate seta and 1 simple seta distally; article 2 ~ 2.0 × longer than flagellar article 1, with 2 simple setae and 2 aesthetascs distally, and 1 simple seta laterally; article 3 minute, with 4 simple setae, 1 penicillate seta, and 1 aesthetasc on distal end. Antenna (Fig. 3D, E) with 10 flagellar articles; peduncular article 3 with 1 process on medial margin; article 5 1.4 × longer than articles 1–4 combined, with serrate lateral cuticular scales and 1 medial process proximally; article 6 0.7 × as long as article 5, widening distally, with serrate cuticular scales, 3 penicillate setae, and several simple distal setae; flagellum with numerous simple setae; flagellar article 1 elongate ovoid, 1.8 × longer than remaining articles combined, 1.3 × longer than peduncular article 6, with cuticular scales laterally.

Mandibles (Fig. 3F, G), molar process distal half finely serrated; incisor with 5 cusps; palp article 2 with serrate setae distally; palp article 3 with serrate setae along with lateral margin. Left mandible (Fig. 3F) with a protrusion between incisor and molar process; spine row composed of 12 serrate setae. Right mandible (Fig. 3G), spine row consisting of 10 serrate setae. Maxillula (Fig. 3H), mesial lobe with 3 robust simple setae and several fine setae distally; lateral lobe with 12 strongly serrate robust setae and several fine setae on distal region. Maxilla (Fig. 3I), mesial lobe shorter than other lobes, with 4 simple setae distally and fine setae along with medial margin; mesial and outer lobes with 4 serrate setae distally. Maxilliped (Fig. 3J, K), endite expanding half of palp article 4, with several short simple setae on medial surface and 2 coupling hooks on medial distal end; distal region of endite rounded and serrated while concave medially, with 4 medial tubercular robust setae; palp article 1 with 2 simple setae distally, article 2 2.8 × longer than article 1, with distally bifid mesial lobe, article 3 square, 0.4 × as long as article 2, with several simple setae distally, article 4 3.0 × longer than article 3, with fine setae on medial margin and several setae laterally, article 5 0.2 × as long as article 4, with several simple setae on distal end; epipod 3.4 × longer than basal width, tapering distally.

Pereopods (Fig. 4A–G), basis and ischium with serrated cuticular scales superodistally; carpus with slightly serrated cuticular scales inferodistally; propodus with 2–4 robust setae inferiorly and numerous short simple setae along with inferior margin. Pereopod 1 (Fig. 4A), basis with 1 penicillate seta superiorly; ischium subequal to basis in length, narrowing proximally; merus 0.6 × as long as ischium; carpus 1.7 × longer than merus; propodus 0.9 × as long as carpus, with 1 penicillate seta on superior distal angle; dactylus 0.2 × as long as propodus, with 2 claws and 1 penicillate seta distally. Pereopods 2–7 (Fig. 4B–G) similar to each other; basis longer than ischium, with 0–2 penicillate setae on superior margin; ischium convex superomedially; carpus ~ 2.0 × longer than merus, with 1 penicillate seta superodistally; propodus similar to carpus in length, with 1 penicillate seta superodistally; dactylus ~ 0.2 × as long as propodus, with 3 claws distally.

Figure 4. 

Joeropsis denticulatus sp. nov., holotype, male A pereopod 1 B pereopod 2 C pereopod 3 D pereopod 4 E pereopod 5 F pereopod 6 G pereopod 7. Scale bar: 0.2 mm.

Pleopod 1 (Fig. 5A) 2.6 × longer than greatest width, slightly concave laterally, narrowing distally; distolateral lobe projected, extending distally; apical lobe rounded, with marginal simple setae distally. Pleopod 2 (Fig. 5B), protopod 2.7 × longer than mid-width, concave distolaterally bearing cuticular scale-setae, with subacute distal end; endopod positioned at 0.7 length of protopod from proximal region; exopod curved outwardly; appendix masculina reaching distal end of protopod, tapering distally. Pleopod 3 (Fig. 5C), endopod 2.1 × longer than width, with 3 plumose setae distally; exopod with cuticular scale-setae along with lateral margin, first article 3.8 × longer than width; second article 0.4 × longer first article. Pleopod 4 (Fig. 5D), endopod 2.2 × as long as wide, tapering distally; exopod vestigial. Pleopod 5 (Fig. 5E) without exopod; endopod 2.0 × as long as wide, tapering distally.

Figure 5. 

Joeropsis denticulatus sp. nov., holotype, male A pleopod 1 B pleopod 2 C pleopod 3 D pleopod 4 E pleopod 5 G uropod. Paratype, female: F pleopod 2. Scale bars: 0.2 mm (A–E, G); 0.1 mm (F).

Uropods (Figs 3A, 5F), protopod extending beyond margin of pleotelson, with strongly produced distal end, serrated medial margin, and 5 simple setae on distal region; endopod with 2 penicillate setae and several simple setae distally; exopod smaller than endopod, with several simple setae distally.

Female similar to male. Pleopod 2 (Fig. 5G) 1.4 × longer than greatest width, tapering distally, with fine setae on distal region; apex subacute, with 2 simple setae.

Males 4.2–5.0 mm, mean 4.7 mm (n = 3); females 3.6–3.8 mm, mean 3.7 mm (n = 3); all from type series.

Whole body is covered with dark brown chromatophores (Figs 2A, 3A).

The colour pattern of the body varies between individuals, especially on pereonite 5. Dark brown chromatophores are occasionally faint or not observable on it.

South Korea (southern coast of the Korean Peninsula).

Joeropsis denticulatus sp. nov. can be identified by the following character states: (1) whole body has chromatophores dorsally; (2) lateral margins of the cephalon are smooth and narrowing anteriorly; and (3) basis of pereopods has serrated cuticular scales superiorly.

Among the total of 77 species, Joeropsis denticulatus sp. nov. is similar to five Joeropsis species in having the laterally smooth and narrowing cephalon, anteriorly rounded pseudorostrum, medially lobed maxillipedal palp article 2, laterally serrated pleotelson, and medially serrated uropods: J. adusta Bruce, 2015; J. affinis Kussakin, 1961; J. brevicornis Koehler, 1885; J. dubia Menzies, 1951; and J. salvati Müller, 1989. Among them, J. denticulatus sp. nov. most closely resembles J. dubia in terms of pereopods with serrated cuticular scales on ischium, but the former can be distinguished from the latter by having pereopod 1 bearing serrated cuticular scales on the basis (vs. lacking serrated cuticular scales in the latter) and distally rounded pleopod 1 in males (vs. distally triangular in the latter) (Menzies 1951; Kussakin 1999). The new species can be distinguished from the remaining four species in terms of maxillipedal palp article 2 (having distally bifid medial lobe vs. having not in the latter species) and pereopods (having serrated cuticular scales on the basis in the former vs. lacking in the latter species) (Koehler 1885; Bocquet and Lemercier 1958; Amar 1961; Kussakin 1961, 1999; Kensley 1975; Müller 1989; Bruce 2015). A detailed comparison of Joeropsis species mentioned above is provided in Table 2.

Holotype, designated here: South Korea • 1 ♂ (3.7 mm); Jeju-do, Jeju-si, Chuja-myeon, Chujado Island; 33°59'08"N, 126°19'08"E; 10 m; 06 Jul. 2019; SCUBA diving; NIBRIV0000862804.

Paratypes : 3 ♂♂ (3.7, 4.0, 4.0 mm), 6 ♀♀ (3.3, 3.4, 3.5, 3.5, 3.6, 3.7 mm), same data as holotype; NIBRIV0000896085.

South Korea • 1 ♂; Jeollanam-do, Sinan-gun, Heuksan-myeon, Hondo-ri, Hongdo Island; 34°40'09"N, 125°10'59"E; 10 m; 19 Jun. 2018; SCUBA diving • 1 ♂, 1 ♀; Jeollanam-do, Yeosu-si, Samsan-myeon, Sangbaeckdo Island; 34°03'15"N, 127°35'00"E; 15 m; 28 Jun. 2017; SCUBA diving • 1 ♂, 4 ♀♀; Gyeongsangbuk-do, Ulleung-gun, Buk-myeon, Cheonbu-ri, Gwaneumdo Islet off Ulleungdo Island; 37°32'43"N, 130°55'22"E; 20 m; 19 Jun. 2016; SCUBA diving.

The specific name, semicircularis is derived from the combination of Latin words semis, meaning “a half”, and circularis, meaning “round”. This name refers to the first flagellar article of the antenna that is semi-circular in shape.

Body (Figs 2B, 6A) almost 4.4 × longer than width; dorsal surface matt and smooth, without setae. Cephalon 0.8 × as long as wide; lateral margins parallel. Pseudorostrum (Fig. 6B) 0.7 × as long as proximal wide, narrowing anteriorly; apex rounded and rough. Eyes positioned sublaterally, bulging. Pereonites not compact, widely spaced, with smooth lateral margins. Pleotelson (Fig. 6C) 1.1 × longer than width, almost globular, tapering on posterior region; lateral margin serrated, with simple setae; caudomedial lobe rounded distally.

Figure 6. 

Joeropsis semicircularis sp. nov., holotype, male A habitus, dorsal view B pseudorostrum C lateral margin of pleotelson D antennula E antenna F flagellar articles of antenna except for setation G left mandible H right mandible I maxillula J maxilla K maxilliped L detail of maxillipedal palp. Scale bars: 0.5 mm (A); 0.2 mm (C–K); 0.1 mm (L); 0.05 mm (B).

Antennula (Fig. 6D), peduncular article 1 square to globular, with cuticular scales along with outer margin; article 2 subsquare, 0.3 × as long as peduncular article 1, with 3 penicillate setae, 2 simple setae, and serrated cuticular scales distally; article 3 0.8 × as long as article 2; flagellar article 1 0.6 × as long as peduncular article 3, with 1 penicillate seta distally; article 2 1.8 × longer than flagellar article 1, with simple setae distally; article 3 minute, with 2 aesthetascs and simple setae on distal end. Antenna (Fig. 6E, F) composed of 6 peduncular articles and 5 flagellar articles; peduncular article 3 with 1 process on medial margin, article 5 about 1.7 × longer than articles 1–4 combined, with cuticular scales laterally, and 2 simple setae and 2 penicillate setae distally; article 6 0.7 × as long as article 5, with cuticular scales along with distolateral margin; flagellum with numerous simple setae; flagellar article 1 semi-circular, 3.8 × longer than flagellar articles 2–5 combined, 1.3 × longer than peduncular article 6, with cuticular scales on convex margin.

Mandibles (Fig. 6G, H), molar process finely serrate in distal half; spine row with 11 serrate setae in left mandible but 10 in right mandible, and incisor with 5 cusps; palp article 2 with 6 serrate setae distally, article 3 with 10 serrate setae along with lateral margin. Maxillula (Fig. 6I) inner lobe with 3 robust simple setae and several fine setae distally; outer lobe with 12 strongly serrate robust setae and 2 simple setae distally. Maxilla (Fig. 6J), inner lobe shorter than 2 outer lobes, with 4 simple setae distally and several fine setae laterally; mesial and outer lobes with 4 serrate setae on distal end, respectively. Maxilliped (Fig. 6K, L), endite almost 1.1 × longer than greatest width, reaching proximal third of palp article 4, truncated distally; distal margin with 4 tubercular robust and 2 short simple setae medially; medial margin with 3 coupling hooks distally; palp article 2 2.4 × longer than article 1, distomedial margin produced, with 3 simple setae distally; article 3 almost 0.5 × as long as article 2, with 3 setae distally; article 4 1.4 × longer than article 3, 2.8 × as long as wide, tapering distally, with 4 simple setae distally and 1 simple seta laterally; article 5 minute, with 6 simple setae distally; epipod ~ 4.3 × longer than basal width; tapering distally; apex subacute.

Pereopods (Fig. 7A–G), basis and ischium with cuticular scales on superodistal end; carpus with cuticular scales inferodistally and numerous short simple setae on inferodistal end; propodus with 2–4 robust setae and numerous short simple setae along with inferior margin. Pereopod 1 (Fig. 7A), basis 2.7 × longer than width, with 1 simple seta on inferior margin; ischium 0.8 × as long as basis; merus 0.6 × as long as ischium, narrowing proximally; carpus 1.6 × longer than merus; propodus 1.2 × longer than carpus, with 1 penicillate seta superiorly; dactylus 0.3 × as long as propodus, with 2 claws on distal end. Pereopods 2–7 (Fig. 7B–G) similar to each other; basis with penicillate setae and simple setae on both lateral margins; ischium ~ 0.8 × as long as basis, convex on superior margin; merus 0.6 × as long as ischium, tapering proximally; carpus subequal to propodus in length, with penicillate setae superodistally; propodus with 1 penicillate seta on superior margin; dactylus with 3 claws and few simple setae distally.

Figure 7. 

Joeropsis semicircularis sp. nov., holotype, male A pereopod 1 B pereopod 2 C pereopod 3 D pereopod 4 E pereopod 5 F pereopod 6 G pereopod 7. Scale bar: 0.2 mm.

Pleopod 1 (Fig. 8A) 2.3 × longer than greatest width; lateral margins concave; distolateral lobe pointed, not extending distally; apical lobe rounded, with several simple setae. Pleopod 2 (Fig. 8B), protopod 2.3 × longer than greatest width, concave on subapical region, acute distally, with several fine setae on subapical region; endopod positioned at 0.6 length of protopod from proximal region; exopod curved outwardly; appendix masculina acute, extending to apex of protopod. Pleopod 3 (Fig. 8C), endopod 2.1 × longer than half-width, with 3 plumose setae distally; exopod composed of 2 articles, with cuticular scale-setae along with lateral margin, subacute distally. Pleopod 4 (Fig. 8D), endopod 1.5 × longer than greatest width, truncated distally; exopod vestigial. Pleopod 5 (Fig. 8E) without exopod; endopod 1.9 × longer than basal width, truncated distally.

Figure 8. 

Joeropsis semicircularis sp. nov., holotype, male A pleopod 1 B pleopod 2 C pleopod 3 D pleopod 4 E pleopod 5 F uropod. Paratype, female G pleopod 2. Scale bars: 0.1 mm.

Uropods (Figs 6A, 8F), protopod extending to distal end of pleotelson, medial margin slightly serrated; distomedial end strongly produced and acute, with 3 simple dorsal setae; endopod with 1 penicillate seta and several simple setae distally; exopod smaller than endopod, with several long simple setae distally.

Female similar to male. Pleopod 2 (Fig. 8G) 1.2 × longer than greatest width, globular, narrowing proximally, tapering distally; apex broadly rounded, with 4 simple setae apically.

Males 3.7–4.0 mm, mean 3.9 mm (n = 4); females 3.3–3.7 mm, mean 3.5 mm (n = 6); all from type series.

The cephalon has a transverse dark brown band of chromatophores across the middle of the cephalon. Pereonite 4 and pleotelson are also covered with chromatophores, but indistinct (Figs 2B, 6A).

The colour pattern of chromatophores varies according to individual. On the cephalon, a transverse dark brown band is always distinct and regular, while on pereonite 4 or pleotelson, the chromatophores are occasionally varied according to the individuals.

South Korea (southern coast of the Korean Peninsula and East Sea).

Joeropsis semicircularis sp. nov. can be identified by the following features: (1) the body has dark brown chromatophores on the cephalon, pereonite 4, and pleotelson; (2) lateral margins of the cephalon are smooth and parallel; and (3) the first flagellar article of the antenna is swollen and semi-circular in shape.

Joeropsis semicircularis sp. nov. resembles four known species by having the cephalon laterally smooth and parallel, the pseudorostrum not concave or pointed distally, maxillipedal palp article 2 lacking medial lobe, and the pleotelson and uropods both laterally serrated: J. dollfusi Norman, 1899; J. latiantennata Nunomura, 1999; J. stebbingi Kensley, 1975; and J. wolffi Müller, 1991 (Koehler 1885; Norman 1899; Amar 1961; Kensley 1975; Müller 1991; Nunomura 1999). Among these species, J. semicircularis sp. nov. is most similar to J. latiantennata by having swollen and semicircular-shaped first flagellar article of the antenna (Nunomura 1999). However, the former differs from the latter by the following characteristic features: (1) the dactylus of pereopods 2–7 has three claws (vs. two claws in the latter); (2) the second peduncular article of the antenna has a process on medial margin (vs. has not in the latter); and (3) the fourth peduncular article of the antenna is not serrated (vs. serrated in the latter) (Nunomura 1999). The new species can be easily distinguishable from the remaining three species by having swollen and semi-circular-shaped first antennal flagellar article (Koehler 1885; Norman 1899; Amar 1961; Kensley 1975; Müller 1991). A detailed comparison of Joeropsis species mentioned above is provided in Table 2.