Chorisquilla orientalis, Hwang & Ahyong & Kim, 2018

Hwang, Hee-Seung, Ahyong, Shane T. & Kim, Won, 2018, A new species of Chorisquilla Manning, 1969 (Stomatopoda: Protosquillidae) from Korea and Japan with redescription of C. mehtae Erdmann & Manning, 1998, Zootaxa 4483 (2), pp. 365-374 : 366-371

Chorisquilla orientalis n. sp.

( Figs. 1–3 )

Protosquilla brooksii .— Fukuda, 1910: 140, pl. IV, figs. 1, 1a.

Gonodactylus spinosissimus .— Komai, 1927: 342, 343, tab. 1.

Chorisquilla spinossisima .— Kim & Rho, 1972: 97.

Gonodactylus chiragra .— Cho et al., 2006: 78 [unnumbered fig.].

Chorisquilla sp.— Hamano, 2005: 32, fig. 2-7e. Ahyong, 2012b: 247.

Type material (all South Korea). HOLOTYPE: NIBRIV0000160376, male (TL 36 mm), Geoje Island, Geojemyeon, Geoje-si , Gyeongsangnam-do, 34°50'05.47''N, 128°42'35.32''E, 4 June 2009.

PARATYPES: Ulleung Island, Dodong-ri, Ulleung-eup , Ulleung-gun , Gyeongsangbuk-do, 37°31'27.69"N, 130°48'22.11"E: MADBK 600301 _020, 1 female (TL 36 mm), 19 October 2001 ; MADBK 600301_018, 1 male (TL 35 mm), 28 November 1991; MADBK 600301_035, 1 male (TL 43 mm), 16 October 2001, coll. S.H. Kim ; MADBK 600301 _010, 3 females (TL 30–38 mm), 2 males (TL 32–38 mm), 22 June 2006 .

Dokdo Island, Dokdo-ri, Ulleung-eup , Ulleung-gun , Gyeongsangbuk-do, 37°29'44.93"N, 130°55'51.38"E: MADBK 600301 _005, 3 females (TL 20–37 mm), 1 male (TL 32 mm), 29 October 2014 ; MADBK 600301_012, 1 male (TL 31 mm), 3 June 2015; MADBK 600301_013, 1 male (TL 32 mm), 1 female (TL 30 mm), 2 males (TL 31–47 mm), 19 October 2014; MADBK 600301_015, 1 male (TL 32 mm), 10 June 2016; MADBK 600301_019, 2 females (TL 35–38 mm), 21 October 2014; MADBK 600301_025, 1 male (TL 37 mm), 1 female (TL 38 mm), 28 October 2014; MADBK 600301_033, 2 females (TL 40–47 mm), 1 male (TL 47 mm), 21 September 2015; AM P 100683, 1 male (TL 32 mm), coll. H.S. Hwang, 29 October 2014; AM P 100685, 1 male (TL 32 mm), coll. H.S. Hwang, 10 June 2016.

Geomundo Island, Geomun-ri, Sasam-myeon , Yeosu-si , Jeollanam-do, 34°2'54.77"N, 127°19'6.01"E: MADBK 600301 _036, 1 female (TL 47 mm), 26 June 2006, Col. S.H Kim ; MADBK 600301_017, 2 females (TL 31–34 mm), 11 March 2010, Col. S.H Kim.

Hakdong-ri, Dongbu-myeon, Geoje-si , Gyeongsangnam-do, 34°49'17.81"N, 128°36'29.30"E: MADBK 600301 _002, 2 juvenile males (TL 12 mm), 9 October 2013.

Sangbaekdo Island, Geomun-ri, Sasam-myeon , Yeosu-si , Jeollanam-do, 34°1'37.57"N, 127°18'58.75"E: MADBK 600301 _032, 1 female (TL 39 mm), 26 June 2002, Col. S.H Kim.

Chujado Island, Chuja-myeon, Jeju-si , Jejudo, 33°56'49.25"N, 126°19'12.35"E: MADBK 600301 _006, 1 male (TL 20 mm), 1 female (TL 38 mm), 31 March 2009 ; NIBRIV0000044633, 1 female (TL 35 mm), 30 June 2004.

Cha-gwido Island, Hangyeong-myeon, Jeju-si , Jejudo, 33°18'45.01"N, 126°8'55.06"E: MADBK 600301 _003, 1 female (TL 13 mm), 3 November 2000 . Marado Island, Daejeong-eup, Segwipo-si , Jejudo, 33°7'14.29"N, 126°16'1.63"E: MADBK 600301 _001, 1 female (TL 10 mm), 4 November 2000 . Hamo-ri, Daejeong-eup, Segwipo-si , Jejudo, 33°12'39.86"N, 126°15'38.23"E: MADBK 600301 _034, 1 male (TL 41 mm), 16 December 2013 .

Other material examined. Banda, Tateyama City, Chiba Prefecture, Japan, 35°36'18.21"N, 140°07'23.90"E: AM P 100676, 1 female (TL 49 mm), coll. C. Norman, on scuba, 29 Aug 1993 ; AM P 100677, 1 female (TL 37 mm), coll. C. Norman, on scuba, 21 Mar 1994; AM P 100678, 2 males (TL 20–39 mm), 1 female, (TL 39 mm), on scuba, coll. C. Norman, 6 Sep 1993.

Description. Eye ( Figs. 1A , 2A ) overreaching distal margin of antennular peduncle article 1, not reaching midlength of article 2. Cornea broadened, not bilobed, dorsoventrally flattened. Ocular scales separate, produced laterally, anterior margins approximately transverse; width together about three-fourths basal width of rostral plate.

Rostral plate ( Figs. 1A , 2A ) sharply trispinous; median spine not reaching to midlength of cornea.

Carapace ( Figs. 1A , 2A ) with anterior margin of lateral plates faintly concave, not extending laterally, anterolateral angle reaching to level of or slightly beyond level of base of rostral plate in specimens TL 32–40 mm or larger.

Antennular peduncle 0.50–0.74CL. Antennal protopod ( Figs. 1A , 2C ) mesial margin with blunt, fixed, anteriorly directed spine; short anteroventral spine below articulation with antennal scale. Antennal scale 0.32– 0.48CL.

Mandibular palp 2-segmented. Maxilliped 1–5 with epipod.

Raptorial claw ( Fig. 2B ) stout; propodus occlusal margin minutely pectinated, with proximal movable spine. Dactylus outer margin with shallow basal notch; outer proximal margin strongly inflated, inner distal margin finely serrated, unarmed.

Thoracic somites 6–8 ( Figs. 1A , 2D ) lateral margin rounded to subtruncate, with low submarginal ridge; somite 8 lateral margin narrowly rounded. Male pleopod 1 endopod ( Fig. 2E ) posterior endite with lateral lobe.

Abdominal somites 1–3 ( Figs. 1A , 2I ) smooth medially, with low marginal carina; posterolateral angle rounded. Abdominal somite 4 ( Figs. 1A , 2I ) smooth medially, with shallow lateral corrugation above low marginal carina; with or without posterolateral spine. Abdominal somite 5 ( Figs. 1A , 2G, I ) smooth on anterior dorsal half, with deep, irregular, elongated longitudinal pits and grooves on posterior half; posteromedian margin strongly concave; lateral surface corrugated, with 2 or 3 longitudinal ridges; posterolateral spine. Abdominal somite 6 ( Figs. 1A , 2G, I ) with paired submedian, intermediate, and lateral bosses, each covered with short spinules, lateral boss with posterior spine; anterior margin adjacent to arthrodial membrane and anterior sclerotized part of arthrodial membrane between somites 5 and 6 each bearing row of minute spinules.

Telson ( Figs. 1A , 2G, I ) broader than long; submedian primary teeth spiniform, with curved, movable apices, articulating submarginally; 8–12 spiniform submedian denticles; 2 spiniform intermediate denticles; intermediate teeth triangular, apex blunt or with minute spinule; lateral teeth short, slender, directed posterolaterally, lateral denticle present or absent. Dorsal surface of bosses and marginal carina covered with minute spinules, those of marginal carina arranged in 2 or 3 uneven rows, with outermost spinules larger, inclined dorsolaterally, partially overhanging lateral margin. Median boss inverted triangular, not extending posteriorly to base of median fissure. Submedian bosses ovate to pyriform and longer than median boss, width distinctly greater than half their length, almost reaching posteriorly to base of intermediate denticles. Small round boss present anterior to each submedian boss. Lateral margin posterior one-third curved, unarmed; proximal two-thirds with 8–14 short spines in specimens>TL 20 mm, posteriormost spine set-off from preceding spines by short convex margin, corresponding to lateral primary tooth, sometimes with minute intermediate denticle at base. Ventral surface ( Fig. 2F ) smooth, without postanal carina.

Uropodal protopod ( Figs. 1A , 2H ) terminating in 2 flattened spines, outer longer; with small lobe between terminal spines; dorsal surface with spine above exopod articulation and a row of 1–3 (usually 2) slender spines proximally, adjacent to articulation with abdominal somite 6. Exopod proximal article with 6–12 (usually 10 or 11) movable spines and stout, fixed distal spine. Endopod slender, unarmed, with shallow median sulcus flanked laterally by low ridge; length 2.82–4.80 × width.

Coloration. Color-in-life mostly ivory to dark brown. Rostral plate, most of carapace, thoracic and abdominal somites, and telson largely brown. Antennular and antennal peduncle, ocular scale, antennal protopod, raptorial claw, pereopods, and uropod ivory. Distal article of antennular peduncle orange.

Measurements. Male (n = 20) TL 12–48 mm, female (n = 24) TL 10–49 mm. Other measurements of holotype: CL 7.43 mm, antennular peduncle length 5.00 mm, antennal scale length 3.40 mm. Komai (1927) recorded specimens to TL 59 mm (as Gonodactylus spinosissimus ).

Etymology. The specific name, orientalis , east, alludes to the East Asian occurrence of the new species.

Habitat. In Korea, from preformed cavities or holes drilled by mollusks in rock walls; depth 10– 25 m. Habitat in Japan not known.

Remarks. Of the known species of Chorisquilla , C. orientalis n. sp. appears to be closely related to the following five species sharing the spinose lateral and dorsal surfaces of the telson and one or more dorsal spines on the proximal surface of the uropodal protopod adjacent to the articulation with abdominal somite 6: C. brooksii (De Man, 1887) , C. mehtae Erdmann & Manning, 1998 , C. hystrix (Nobili, 1906) , C. kroppi Ahyong & Erdmann, 1998 , and C. spinosissima ( Pfeffer, 1888) . Of these C. orientalis n. sp. is most similar to C. mehtae , from Indonesia, sharing short lateral telson spines, numerous short, slender dorsal spinules that do not obscure the dorsal surface, and broad, pyriform submedian telson bosses. Chorisquilla orientalis n. sp., however, can be readily distinguished from C. mehtae by the features of abdominal somite 5, telson and ocular scales. In C. orientalis , the dorsal surface of abdominal somite 5 is ornamented with deep longitudinal grooves and irregular pits (versus largely smooth with few small, shallow pits in C. mehtae ). In C. orientalis , the anterior margin of abdominal somite 6 and the anterior sclerotized portion of the arthrodial membrane between somites 5 and 6 each bear a transverse row of spinules; both rows of spinules are absent in C. mehtae . The median boss on the telson is more triangular in C. orientalis , with the anterior margin more weakly rounded than in C. mehtae , and a rounded boss present anterior to each submedian boss in the new species (absent in C. mehtae ). The ocular scales are more transversely oriented and proportionally wider in C. orientalis than in C. mehtae . Conversely, in C. mehtae , the anterior margins of the ocular scales are distinctly oblique to the body axis, and together, are about half the basal width of the rostral plate (versus about three-fourths). Chorisquilla orientalis also reaches a considerably larger size than C. mehtae , to TL 59 mm versus TL 17 mm, and males are mature by at least TL 20 mm (compared to C. mehtae , which are mature by at least TL 11 mm); Chorisquilla orientalis is presently the largest known species of the genus.

Like C. orientalis , C. brooksii also has short dorsal spines on the telson that do not obscure the surface, but can be separated by the much wider submedian telson bosses (length less than twice width versus less than twice width) and greater lateral marginal spination in adults (8–14 versus 4–6). The remaining species of the genus with a spinose telson, C. hystrix , C. kroppi , and C. spinosissima , all differ from C. orientalis in having long lateral and dorsal telson spines that obscure the surface and outline of the telson.

Chorisquilla orientalis n. sp. shows allometric changes in the shape of the ocular scales and anterior margin of lateral plates of carapace, and in the spination of the telson. The ocular scales become wider with increasing body size, with the combined width 60% of the basal rostral width in juveniles increasing to 75% in adults. As in postlarvae and juveniles of other protosquillids, the dorsal bosses of abdominal somite 6 in the smallest juveniles of C. orientalis are posteriorly armed and slenderer than in adults. The number of lateral spines of the telson also increases with body size. Four lateral marginal spines are present on the telson by TL 11 mm ( Figs. 1B , 3B ), 8–13 spines by TL 20–48 mm ( Figs. 1A , 2G ), and 14 spines by TL 49 mm. Also, the anterior margin of the lateral plate on carapace of C. orientalis n. sp. slopes more posteriorly in smaller specimens. In specimens to about TL 32 mm, the anterolateral angle of the lateral plates of the carapace does not reach anteriorly to the level of the base of the rostral plate. By TL 32–40 mm, the anterolateral angle of the lateral plates of the carapace reach to or slightly anterior to the level of the base of the rostral plate.

Previous records of C. brooksii from Japan ( Fukuda, 1910), reidentified as C. spinosissima by Komai (1927), are clearly referable to C. orientalis as shown by Fukuda (1910: pl. IV, fig. 1, 1a). Only one species of Chorisquilla , C. spinosissima , has been reported from Korea ( Kim & Rho, 1972). This single report of C. spinosissima is not accompanied by figures or descriptive remarks, and the specimen on which the record is based is no longer extant. Extensive surveys in Korean waters over the past three decades, however, have only ever revealed a single species of Chorisquilla , that named here as C. orientalis . Given the broad morphological similarities between C. orientalis n. sp. and C. spinosissima , especially in juveniles with lesser developed telson spination, and Komai’s (1927) misidentification of C. spinosissima from Japan, we regard the record of Kim & Rho (1972) to be almost certainly based on C. orientalis . Similarly, the recent record of Gonodactylus chiragra from Korea figured by Cho et al. (2006) is clearly based on C. orientalis . Two other gonodactyloids, Gonodactylaceus falcatus (Forskål, 1775) (Hwang et al. 2018) and Taku spinosocarinatus (Fukuda, 1911) ( Ahyong et al. 2018), have recently been reported from Korean waters, and are distinguished in the key below.

Distribution. Korea and central Japan (Tateyama, Chiba Prefecture, to Misaki, Osaka Prefecture).

Figures

FIGURE 1. Chorisquilla orientalis n. sp. A, male holotype, TL 36 mm, NIBRIV0000160376. B, female paratype, TL 13 mm, MADBK 600301_003. (Preserved coloration)

FIGURE 2. Chorisquilla orientalis n. sp., male holotype, TL 36 mm, South Korea, NIBRIV0000160376. A, anterior cephalothorax; B, raptorial claw; C, antennal protopod; D, thoracic somites 6–8, right lateral view; E, right male pleopod 1 endopod; F, telson, ventral view; G, abdominal somites 4–6, telson, and uropod; H, right uropod, ventral; I, abdominal somites 3–5 and telson, right lateral view. Scale bars: A–I = 1.0 mm.

FIGURE 3. Chorisquilla orientalis n. sp., juvenile male paratype, TL 12 mm, South Korea, MADBK 600301_002. A, anterior cephalothorax; B, telson. Scale bars = 1.0 mm.