Spongiocaris neocaledonensis, Goy, Joseph W., 2015

Goy, Joseph W., 2015, Stenopodidean shrimps (Crustacea: Decapoda) from New Caledonian waters, Zootaxa 4044 (3), pp. 301-344 : 313-320

Spongiocaris neocaledonensis n. sp.

( Figs. 12–14 )

Non Spongiocaris yaldwyni .— Goy, 2010: 220, figs. 65.3A, B, 65.4E, 65.12J.

Type material. HOLOTYPE: New Caledonia, Norfolk Ridge. SMIB 4, stn DW58, 22°59.8’S, 167°24.2’E, 560 m, 9.III.1989, male, 1 female (MNHN-NA 12000). ALLOTYPE: New Caledonia, Norfolk Ridge. SMIB 4, stn DW58, 22°59.8’S, 167°24.2’E, 560 m, 9.III.1989, female (MNHN-NA 12000). PARATYPES: SMIB 4, stn DW61, 22°59.9’S, 167°22.8’E, 550 m, 10.III.1989, 3 females (1 ov.) (MNHN-NA 12001).— SMIB 4, stn DW63, 22°58.7’S, 167°21.1’E, 520 m, 10.III.1989, 1 female ov. (MNHN-NA 12004).— SMIB 4, stn DW64, 22°55.3’S, 167°16.4’E, 460 m, 10.III.1989, 1 male, (MNHN-NA 12005).— New Caledonia. BIOCAL, stn DW 46, 22°53’S, 167°17’E, 570–610 m, 30.VIII.1985, 1 male, (MNHN-NA 12007).—MUSORSTOM 4, stn CP215, 22°55.7’S, 167°17’E, 485–520 m, 28.IX.1985, 3 females (2 ov.) in Regardella okinseana, ( USNM 256952).—BIOGEOCAL, stn CP290, 20°36.91’S, 167°03.34’E, 970– 760 m, 27.IV.1987, 1 female, (MNHN-NA12002). — Loyalty Islands. W. Lifou, N. Baie du Santal, CALSUB, Dive 7, 22°48’S, 167°05’E, 966– 845 m, 25.II.1989, 1 male on gorgonian, (MNHN-NA 12003).

Diagnosis. Small commensal spongicolid shrimp associated with sponges or gorgonians, with slightly depressed body bearing few spines; carapace with distinct cervical groove with 4–10 small spines; small branchiostegal spine present; small supraorbital, antennal, and hepatic spines sometimes present; rostrum moderately long reaching to middle of last antennular peduncle segment with 4–6 dorsal, 0–1 ventral, 0–2 lateral spines; pigment of cornea restricted to submedial ring in starburst pattern; unarmed epistome; endopod of maxillule unarmed; setiferous organ of third maxilliped covering distal half of propodal ventral margin; first pereiopod with well developed setiferous organ; males with spines on meri, propodi of third pereiopods, single forward curving ventral medial spine on fifth abdominal pleomere; females with entire third pereiopods glabrous, lacking ventral medial spine on fifth abdominal somite; third pereiopod ventral propodal margin distally with dense fringe of setal brushes; fourth and fifth pereiopods with carpi distinctly 3-segmented; first to fifth pereiopods lack epipods but bear cicatrices; posterior margin of fifth abdominal pleomere ending in 4 or 5 spines, that of sixth pleomere in 3–9 spines; few dorsal spines on sixth abdominal pleomere; uropodal endopodite with 2 terminal dorsal hairs.

Description. (Holotype, male MNHN-Na-12000) Rostrum ( Figs. 12 A, B) broad at base, slightly compressed anteriorly; moderately long, reaching past middle of last antennular peduncle segment; dorsal margin with 5 spines followed by blunt tubercle; no ventral or lateral spines.

Carapace ( Figs.12 A, B) with distinct cervical groove bearing 10 small spines. Small spine at rostral base with 2 smaller spines behind located dorsomesially. Small antennal and branchiostegal spines, large spine at pterygosmial angle. Group of 3 small anterolateral spines present. Ventrolateral angle rounded, posterolateral angle of branchiostegite broadly rounded.

Abdominal pleomeres ( Fig. 12 A) generally glabrous, lacking carinae. First to fifth pleomeres with rounded pleural margins; sixth pleomere’s pleuron ending in acute point. Posterior margin of fifth pleomere ending in 4 spines, that of sixth in 3 spines. Dorsally, sixth pleomere bears row of 3 medial spines, 2 large submedial and 2 smaller lateral spines. Only fifth pleomere with strong median ventral spine, directed anteriorly.

Eyes ( Figs. 12 A, B) well developed, of moderate size; cornea globular with black pigment restricted to submedial ring arranged in starburst pattern. No spinules on ophthalmic peduncle.

Telson ( Fig. 12 C) long, broad subtriangular, with median groove flanked by 2 longitudinal carinae. Telsonal base with pairs of small outer and medial spines. Dorsal surface of carinae with left side bearing 5 spines, right bearing 4. Few setae within median groove and outside carinae. Lateral margins of telson with 7 left, 8 right acute teeth. Posterior margin rounded, setose with 10 small teeth.

Uropods ( Fig. 12 C) well developed, about as long as telson. Basal segment strong with 2 small teeth posterolaterally. Exopodite broader than ovate endopodite; outer margin of left exopodite with 10 teeth, that of right with 11 teeth; dorsal surface of exopodite with 2 strong ridges. Margins of endopodite unarmed, dorsally with 1 strong ridge, terminating in 2 curved dorsal hairs. Unarmed margins of exopoditess, endopodites with long plumose setae.

Epistome ( Fig. 12 E) unarmed, rounded anteriorly, with rounded lateral extensions. Labrum normally developed, posterior margin acutely rounded. Paragnath slightly bilobed. Thoracic sternites ( Fig. 12 D) narrow with 2 submedian spinules on segments 4, 6, 7, 8 and 1 submedian spinules on segment 5.

Antennular peduncle ( Fig. 12 B) moderately long, extending to middle of scaphocerite. Basal segment more than 2.0 times length of second segment, third same length as second. Outer margin with small rounded stylocerite, few setae; 2 small spines on distodorsal inner margin. Upper and lower flagella short, but well developed; upper flagellum unarmed, lower flagellum consisting of 22 segments with numerous aesthetascs along proximal to midlength.

Antenna ( Figs. 12 A, B) with stout basicerite with 2 strong distodorsal spines on outer margin, medial carina with rounded distal extremity, sharp hooked spine ventrolaterally. Carpocerite unarmed, short not exceeding first antennular peduncle segment. Antennal flagellum long, slender, unarmed, extending approximately to tip of telson. Scaphocerite broad, slightly quadrangular, dorsally bearing 2 strong longitudinal carinae; outer margin slightly concave bearing 3 small spines proximally, 5 small teeth distally, larger distal most tooth; inner margin convex, fringed with long plumose setae.

Mandible ( Figs. 12 F, G) robust, with short, fused molar and incisor processes. Molar surface with 3 small teeth; incisor bearing 2 stout teeth distally followed by 6 small teeth proximally. Palp well developed, 3-segmented. Proximal segment without setae; middle segment setose mesially, on distal outer margin; distal segment densely setose laterally and distally.

Maxillule ( Fig. 12 H) with slender, unarmed, undivided endopodite. Proximal endite broad, roundly truncated distally with numerous simple and compound spinose setae. Distal endite much narrower, rounded, with setae along its margins.

Maxilla ( Fig. 12 I) with numerous plumose setae on both lobes of coxal and basal endites, proximal coxal endite broadest. Endopodite long, but robust, not exceeding anterior margin of scaphgnathite, with 16 plumose setae along margins. Scaphognathite long, anterior portion broader than posterior portion, with numerous plumose setae along margin.

First maxilliped ( Fig. 14 A) with 2-segmented endopodite. Proximal segment 2.0 times longer than distal segment with 10 long plumose along outer margin, 3 simple setae on inner margin. Distal segment tapering with 10 long plumose setae on outer margin, stout terminal spine, long plumose seta on inner margin. Basipodite large, rounded anteriorly and posteriorly, slightly concave near middle, with outer margin bearing dense fringe of setae. Coxopodite bilobed with numerous seate. Exopodite well developed, flagellum arising from unsegmented peduncle with 5 proximal and 20 distodorsal long plumose setae. Moderately large epipod with slender proximal and distal lobes approximately equal in length, small arthrobranch also present.

Second maxilliped ( Fig. 14 B) with 5-segmented endopodite. Dactylus suboval, slightly longer than broad, with dense fringe of setae along distodorsal margin. Propodus equal to dactylar length, densely setose on dorsal margin, ventral margin unarmed, notched proximally, rounded distally. Carpus triangular, narrowed proximally, equal to propodal length, densely setose on outer margin. Merus long, slightly concave medially, about 4.0 times carpal length with fringe of short setae on inner margin, 4 setae on outer margin. Ischium and basis not fused, both with few setae. Coxa with small epipod, arthrobranch and lateral podobranch. Exopodite long, slender, undivided with 3 proximal and 20 distodorsal long plumose setae.

Third maxilliped ( Fig. 14 C) with well developed, 5-segmnted endopodite. Dactylus slender, tapering, 2.0 times longer than broad, dorsal margin with 3 simple setae, numerous long simple setae mesially and on inner margin. Propodus 2.0 times dactylar length, 4 outer setae, entire inner margin with dense fringe of setae on distal setiferous organ. Carpus about equal propodal length, merus 2.0 times carpal length, ischium equal meral length; all with few setae on outer margins, densely setose in double row on inner margins. Basis without exopodite, sparsely setose on inner margin. Coxa bearing small epipod, two small arthrobranchs.

First pereiopod ( Fig. 14 D) small, slender, when stretched reaching past scaphocerite, segments with few simple setae on margins. Dactylus less than 0.5 propodal length. Fingers slightly compressed, with hooked highly chitinized tips, overlapping when closed. Cutting edges rather indistinct with propodus and dactylus bearing chitinous ridge along inner margins. Fingers and distodorsal extremity of palm with small tufts of long setae arranged like brushes. Distoventral carpus and proximoventral propodus with setiferous organ. Carpus longest segment, over 2.0 times propodal length. Merus almost equal carpal length, ischium equal to propodal length. Basis and coxa short, unarmed, no epipod present.

Second pereiopod ( Fig. 14 E) similar to first, but longer, stronger, segments with few simple setae along margins. Fingers with hooked, heavily chintinized tips, overlapping when closed. Cutting edges entire, chitinized ridges along inner dactylar and prpodal margins. Fingers and distdorsal extremity of palm with small tuft of long setae. Carpus longest segment, about 1.5 times propodal length, merus 0.8 carpal length, ischium 0.3 meral length. Basis and coxa short, unarmed, no epipod present.

Third pereiopod ( Figs. 12 A) largest, strongest, almost as long as entire body length, with few simple setae along margins of segments. Fingers elongate with heavily chitinized hooked crossing tips, distally bearing small tufts of long setae. Dactylus with distal chitinous ridge along cutting edge, proximally with large sharp tooth, smaller rounded tooth. Propodal cutting edge with distal chitinous ridge, proximally fossa for receiving large dactylar tooth, crowned with large rounded tooth followed by serrate ridge. Propodus longest segment with outer margin distally bearing dense fringe of setal brushes. Carpus less than 0.3 propodal length, narrowing proximally. Merus about 0.8 propodal length with distomedial ridge, 5 blunt dorsal spines, 4 blunt ventral spines. Ischium 0.5 meral length, unarmed. Basis and coxa short, stout, unarmed, no epipod present.

Fourth, fifth pereiopods ( Figs. 14 I, J) long, slender, fifth slightly longer than fourth, with simple setae along margins. Dactyli triunguiculate, with smaller proximal tooth on accessory spine. Unguis short, curved, clearly separated from dactylar corpus. Propodi about 0.3 carpal lengths with 14 movable spines on ventral margins. Carpi longest segments, divided into 3 subsegments, last 2 terminating in movable spine at distodorsal margin. Meri about as long as carpi, ischia 0.3 times meral length. Bases and coxae short, stout, unarmed, without epipods.

First pleopod ( Fig. 12 A) uniramous, second to fifth biramous, all lacking appendices, bearing no spinules.

Maxillipeds Pereiopods

I II III I II III IV V Measurements (mm). Holotype: PCL: 8.3; RCL: 11.8; TL: 31.3; Allotype—PCL: 10.5; RCL: 12.6; TL: 34.0. Paratypes & additional material: PCL: 4.3–11.4; RCL: 6.0–13.4; TL: 14.4–38.2. Eggs in 4 ovigerous females were few in number (2–9) while the allotype bore 62 eggs. All of the eggs were in early stages of embryonic development averaging 2.04 × 1.70 mm in size.

Distribution. New Caledonia, Norfolk Ridge; Loyalty Islands in 460– 970 m.

Etymology. The name neocaledonensis refers to the species type locality, New Caledonian waters.

Coloration. Unknown.

Type locality. New Caledonia, Norfolk Ridge, 22°59.8’S, 167°24.2’E, 560 m

Allotype (female, MNHN-NA-12000) ( Figs.13 A–D). Sexual differences from the holotype include: inflated carapace; broader thoracic sternites with fourth, fifth bearing 2 rounded projections, others unarmed; no ventral median spine on fifth abdominal somite; abdominal pleura expanded, overlapping each other; posterior margin of fifth abdominal somite with 5 spines; sixth abdominal somite with row of 3 dorsal spines, 9 posterior margin spines; third pereiopod completely glabrous; pleopods much larger and more setose.

Five paratypes and 5 additional specimens agree well with the holotype and allotype and show the same sexual differences. The spination of the third pereiopods varies in the males ( Figs. 14 F–H) with larger males being less spinose and the meral distdorsal ridge ending in 1 or 2 spines. Spination of the carapace is variable with some specimens bearing hepatic, superior and inferior orbital spines and others lacking an antennal spine. Other variation in spination include: 4–6 dorsal, 0–1 ventral and 0–2 lateral spines on the rostrum; 4–10 cervical groove spines; 4– 6 outer margin spines on scaphocerite; 8–16 ventral movable spines on the propodi of the fourth and fifth pereiopods; 4–9 spines on the telson’s median carinae; 5–10 spines on telson’s lateral border; 6–12 posteror teeth on telson; and 8–14 teeth on outer margin of uropodal exopodite. This slight variation in body spination probably reflect allometric growth changes and normal variation in the species.

Host. Three females were taken from the hexactinellid sponge Regardella okinoseana Ijima, 1901 at MUSORSTOM 4 station 215 and another female from the same sponge species at BIOCAL station 46. The second largest male (MNHN-NA 12003) was collected on a gorgonian octocoral by the CALSUB expedition.

Systematic position. Spongiocaris neocaledonensis closely follows the definition of the genus Spongiocaris given by Bruce & Baba (1973). The genus Spongiocaris needs to be revised ( Saito & Komai 2008; Goy 2010) since some members assigned to other spongicolid genera actually need to be transferred to Spongiocaris . These species include Spongicola japonica Kubo, 1942 , Spongicola cubanica Ortiz, Gómez & Lalana, 1994 , and Spongicoloides koehleri ( Caullery, 1896) . A revision of the genera Spongiocaris Bruce & Baba, 1973 and Spongicolides Hansen, 1908 is in progress to affect these transfers. That said, Spongiocaris neocaledonensis is most similar to Spongicola japonica in rostral, carapacial and telsonal spination, while the new species’ eye pigmentation, morphology of the third pereiopods approaches the conditions seen in Spongicoloides koehleri . In overall appearance S. neocaledonensis resembles S. yaldwyni ( Goy, 2010) and its branchial formula is the same as S. yaldwyni , except for the presence of an epipod on the third maxillipeds. The new species can be easily distinguished from the other seven species in the genus by the segmentation of the carpus of the last two pairs of pereiopods, the presence of the third maxilliped’s setiferous organ, and the dense fringe of setal brushes on the third pereiopod propodus.

Remarks. Spongiocaris neocaledonensis is the only member of the genus with well developed setiferous organs on the third maxillipeds and first pereiopods; approaching the condition of many members of the family Stenopodidae . All other members of the genus Spongiocaris lack these structures, except Spongicoloides koehleri and Spongicola japonica which bear rudimentary setiferous organs on the first pereiopods. The main function of these setiferous organs in shallow water stenopodideans is for self-grooming (Bauer 1981, 1989). The function of these structures in a deep water hexactinellid sponge commensal is hard to explain. Perhaps in combination with the dense setal brushes on the third pereiopods, these setiferous organs are used to sweep silty deposits off the shrimp’s body as well as the internal sponge chamber in which the shrimp occupies.

The bathymetric range of the new species is from 460 to 966 m, which is similar to that of Spongicola japonica at 300– 807 m. Collection of deep water hexactinellid sponges and careful examination of their internal chambers can yield commensals, as evidenced by the capture of four specimens of Spongiocaris neocaledonensis from two specimens of the hexactinellid sponge Regardella okinoseana. The unique holotype of S. yaldwyni was taken from Regardella okiniseana like the new species. Use of deepsea submersibles can uncover new commensal relationships that are normally lost to trawling or dredging sampling methods. The capture of a male S. neocaledonensis on a gorgorian octocoral was accomplished by the use of the deepsea submersible “Cyana” during the CALSUB expedition. This represents the first record of a stenopodidean shrimp in a commensal relationship with an alcyonarian. Continued future use of deepsea submersibles for invertebrate collections may reveal other new and interesting symbiotic associations such as this one.

Figures

FIGURE 12. Spongiocaris neocaledonensis sp. nov. Male holotype, MNHN Na- 12000. A, lateral view; B, carapace, dorsal view; C, fifth to sixth pleomeres, telson and uropods, dorsal view; D, thoracic sternites; E, epistome and labrum; F, right mandible, dorsal view; G, right mandible, ventral view; H, maxillae; I, maxilla. Scale bars = 1.0 mm.

FIGURE 13. Spongiocaris neocaledonensis sp. nov. Female allotype, MNHN Na- 12000. A, carapace and abdomen, lateral view; B, carapace, dorsal view; C, fifth, sixth pleomeres, telson and uropods; D, thoracic sternites; E, egg; F; dactylus, propodus and carpus third pereiopod. Scale bars = 1.0 mm.

FIGURE 14. Spongiocaris neocaledonensis sp. nov. A – E, I, J, male holotype, MNHN Na- 12000; F, male paratype, NMNH Na- 12003; G, male paratype, MNHN Na- 12005; H, male paratype, MNHN Na- 12006. A, first maxilliped; B, second maxilliped; C, third maxilliped; D, first pereiopod; E, second pereiopod; F – H, third pereiopod; I; fourth pereiopod; J, fifth pereiopod. Scale bars = 1.0 mm.