Spitontocaris sica Rathbun, 1902

Ayón-Parente, Manuel, 2017, The genus Spirontocaris Spence Bate, 1888 (Caridea, Decapoda, Thoridae) in western Mexico, Zootaxa 4320 (2), pp. 305-320 : 312-317

publication ID	https://doi.org/ 10.11646/zootaxa.4320.2.6
publication LSID	lsid:zoobank.org:pub:39A76Add-9B5D-4Ba0-B499-B03Bfb1F1Af1
DOI	https://doi.org/10.5281/zenodo.6025403
persistent identifier	https://treatment.plazi.org/id/F93D87A4-FFC7-146A-EEF6-F95311B13128
treatment provided by	Plazi
scientific name	Spitontocaris sica Rathbun, 1902
status

Treatment

Figs. 4B, C View Figure 4 , 5C View Figure 5 , 6 View Figure 6 –9 View Figure 6 View Figure 7 View Figure 8 View Figure 9

Spitontocaris sica Rathbun, 1902: 894 ; 1904: 60 (key), 69, fig. 25. Schmitt, 1921: 55, fig. 32. Holthuis, 1947: 8 (list), 37 (key). Kozloff, 1974: 166. Word & Charwat, 1976: 155 (textfig.), 156. Hayashi, 1977: 158 (key). Butler, 1980: 19 (key), 167 (text fig.), pl. 7D. Wicksten, 1980: 363; 1987: 54; 1989: 313; 1990: 590 (key); 2012: 93, fig. 23 D. Hendrickx, 1993: 307 (list); 2012: 314 (table). Martin & Zimmerman, 1997: 80, fig. 2.11. Chace, 1997: 57. Stull et al. 1999: 195 (table).

Material examined. Off the west coast of Baja California, Mexico. TALUD XVI-B. St. 5 (28°48'06"N, 115°24'6"W) GoogleMaps , May 24, 2014, BS, 772–776 m, 1 M (CL 8.1 mm), 26 F (CL 7.6–10.6 mm), and 1 ovig. F (CL 9.2 mm) (ICML-EMU-10931); 3 F (CL 0.8–11.8 mm) (ICML-EMU-10936); 4 F (CL 9.4–11.0 mm) (ICML-EMU- 10949). St. 6 (29°08'9"N, 115°33'26"W) GoogleMaps , May 24, 2014, 12 F (CL 7.7–10.3 mm), BS, 1004–1102 m (ICML-EMU- 10932). St. 7 (29°21'12"N, 115°39'8"W) GoogleMaps , May 31, 2014, 2 M (CL 6.7–7.5 mm) and 28 F (CL 6.7–10.7 mm), BS, 710–750 m (ICML-EMU-10933). St. 17 (29°54'18"N, 116°01'30"W) GoogleMaps , May 29, 2014, BS, 734–774 m, 1 M (CL 7.1 mm), 10 F (CL 6.3–9.7 mm) (ICML-EMU-10934), and 3 damaged specimens (CL 7.9–8.5 mm) (ICML-EMU- 10937). St. 18 (30°39'16"N, 116°39'18"W) GoogleMaps , May 25, 2014, BS, 740–785 m, 2 M (CL 6.2–7.4 mm) and 35 F (CL 4.6–11.1 mm) (ICML-EMU-10935); 2 F (CL 9.6–9.7 mm) and 1 ovig. F (CL 9.7 mm) (ICML-EMU-10938); 1 M (CL 6.15 mm) and 7 F (CL 5.85–10.98 mm) (ICML-EMU-10947); 1 M (CL 8.2 mm) and 3 F (CL 8.9–11.4 mm) (ICML-EMU-10948).

Additional material examined. Type series. Santa Barbara Channel, California, 5 F (CL 9.5–12.6 mm), April 6, 1890, " Albatross " St. 3200, 265 fm (484 m) (USNM-25261).

Description ( Figures 4B, C View Figure 4 , 5C View Figure 5 , 6 View Figure 6 –9 View Figure 6 View Figure 7 View Figure 8 View Figure 9 ). Body slender, stout. Rostrum long and deep, about 0.8 to 1.2 carapace length, constricted at base, blade-like in middle section, midaxis of rostrum curved upwards, lower limb of blade broader than upper, distal portion styliform, slightly ascending; upper margin with 9–15 teeth, two beyond orbit, proximal rostral teeth of similar size, distal forming a cluster of 4–7 smaller, closely set teeth; lower margin with 3– 8 teeth. Carapace carinate along almost all dorsal margin; two supraorbital spines, upper stronger; suborbital angle obtuse, antennal spine sharp, pterygostomial spine wanting of weak.

Abdomen dorsally smooth; ventral margin of somite 2 broadly convex; third somite slightly produced posteriorly; fourth and fifth pleura deeply recessed at articular knob, fourth without and fifth with small posterolateral spine; sixth as long as telson, posteroventral spine weak. Telson long, slender, about 4 times as long as wide, 3–4 pairs of small dorsal spines; posterior margin pointed at middle, with three pairs of lateral spines, outer pair short, intermediate pair the longest, inner pair slightly shorter than intermediate pair.

Eye large, cornea well developed, as long as stalk. Antennular peduncle long, not reaching rostral apex, stylocerite short, third segment less than half length of second, second and third each with a distal marginal spine. Antennal scale about 3 times as long as broad, not reaching rostral apex, outer terminal spine stout, moderately long, tip not quite reaching distal margin of scale. Basicerite with one upper outer lobe and one lower outer spine; carpocerite reaching proximal half of scale.

Third maxilliped moderately long, reaching tip of antennal scale, epipod present.

Pereipod 1 shorther than third maxilliped, slightly stouter, epipod present, terminally hooked. Pereiopod 2 longer than pereiopod 1, carpus 7–segmented, third segment the longest, shorter than segments 4–7 combined, cheliped one half longer than carpus ultimate segment. Pereiopods 3–5 of about same length, merus of pereiopod 3 with 5–9 spines, that of pereiopod 4 with 6–8 spines, that of pereiopod 5 with 4–7 spines; dactyli smooth, ending in ungui, proportionally shorter than propodus from 3rd to 5th (0.4–0.3x).

Uropod shorter than telson; outer margin of exopod ending in two spines, inner spine movable.

Size. Maximum known size (CL): males, 8.0 mm; females, 13.3 mm; ovigerous females, 8.6–11.4 mm ( Butler 1980). Male, 8.2 mm (present study).

Colour. The colour illustration provided by Butler (1980) and the corresponding description shows a mostly yellowish specimen, with many red blotches on the carapace and abdominal somites, and darker reddish pereiopods ( Figure 5B View Figure 5 ). A photographed specimen captured during the TALUD cruises ( Figure 5C View Figure 5 ) presents a more orange background, with similar reddish spots on the carapace and abdominal somites; pleopods are also reddish vs. pale yellow in the figure provided by Butler (1980).

Geographic and depth distribution. Type locality: Santa Barbara Channel, California, USA. From Restauration Bay, British Columbia, Canada, to San Benito and Cedros Islands, Baja California, Mexico ( Wicksten 2012). From 88 to 849 m depth, most abundant in 90–183 m ( Butler 1980). In California, most specimens have been captured between 150 and 550 m ( Wicksten 2012). Material from this study was caught between 710 and 1102 m depth.

Distribution in Mexico. Wicksten (1987) was the first and the only one so far to have reported material of S. sica from western Mexico: 10 specimens, between San Benito and Cedros Islands (28°18'N, 115°23'W), at 247–265 m depth (SIO C2546). The material collected during present study (five samples between 28°48'N and 30°39'16"N) ( Figure 1 View Figure 1 ) significantly increases the number of known localities from off western Mexico (from one to six) and confirm the presence of a large population of S. sica along the northern part of the Baja California Peninsula.

Ecology. Environmental data recorded during this survey indicate that S. sica lives below the Oxygen Minimum Zone (OMZ) (710–1102 m) that occurs along the Baja California Peninsula ( Helly & Levin 2004, Papiol et al. 2016), in poorly oxygenated water (0.22 to 0.40 ml O2/l), in a temperature range of 4.38 to 5.81°C. No specimens of S. sica were found in samples obtained with the benthic sledge operating in the shallower (296–665 m) or deeper (1118–2136 m) depth ranges during the same cruise. Sediments associated with this species are dominated by silt (>72% in 4 out of 5 localities), with organic carbon content of 18 to 52 mg C org/g. In California, it forms part of the diet of the sandpaper skate, Bathyraja kincaidii (Garman, 1908) ( Rinewalt et al. 2007)

Remarks. Compared to S. holmesi , the antennal scale distal margin of S. sica is obliquely straight vs. rounded in the former species, and the lateral spine does not quite reach the anterior margin of the scale ( Figure 5C View Figure 5 ).

Spirontocaris sica (the "offshore blade shrimp") was originally described from the Santa Barbara Channel from material (20 specimens in the type series) collected by the "Albatross" at 265 fathoms (484 m) (St. 3200). It was collected additionally in 19 stations of the "Albatross", from Point Arena to San Diego, in a depth range of 211–464 fathoms ( Rathbun 1904).

Part of the material collected during this study (ICML-EMU-10931 and 10932) was compared to the type series used in the original description. Although the shape and length of the rostrum is quite variable in this species, the new material collected during the TALUD XVI-B cruise fit well with the specimens of this type series.

Spirontocaris sica is very similar to S. holmesi but can be differentiated from the former by several characters, including: the rostrum of S. holmesi is usually proportionally deeper when compared to carapace height and feature one small tooth on the ventral margin of the styliform section of the rostrum, vs. no such tooth in S. sica ; the pair of dorsal teeth on the carapace is placed at about mid-length of the carapace in S. holmesi , vs. in the proximal third in S. sica ; S. holmesi has an epipod on pereiopods 1 and 2, vs. only on pereiopod 1 in S. sica ; the ventral margin of the second pleura is almost straight in S. holmesi , vs. frankly convex in S. sica ; the tip of the antennal scale is rounded in S. holmesi vs. obliquely straight in S. sica .

Although S. sica has been collected in several localities off California and off Canada, illustrations available in literature are scarce. The original drawing by Rathbun (1904: lateral view of carapace) was later reproduced by Schmitt (1921). Butler (1980) provided the lateral and dorsal views of an entire specimen and a colour plate of another specimen. As in the case of S. holmesi, Martin & Zimmerman (1997) reproduced the figures provided by Word & Charwat (1976) and Butler (1980), and the description provided by Butler (1980). Wicksten (2012) provided a lateral view of the carapace of a specimen collected by the Velero IV off Dana Point (33°23.37'N, 117°41.54'W), California (LACM 1975-266) (M.K. Wicksten, pers. comm. April 2017). With the exception of Mary J. Rathbun's figure of the carapace, the illustrations provided herein are the first available based on the type material of S. sica . ( Figures 6 View Figure 6 , 7 View Figure 7 ). In addition, several specimens collected during this survey were also illustrated as useful comparative material ( Figures 8 View Figure 8 , 9 View Figure 9 ).