Spongicoloides weijiaensis Xu, Zhou & Wang, 2017

Rengaiyan, Periasamy, Palayil, John Kurian & Ingole, Baban, 2022, A new report on the deep-sea sponge-associated Spongicoloides weijiaensis Xu Zhou & Wang, 2017 (Decapoda: Spongicolidae) from the Southwest Indian Ocean Ridge, Zootaxa 5195 (3), pp. 267-277 : 269-272

Spongicoloides weijiaensis Xu, Zhou & Wang, 2017

( Fig. 1–6 )

Spongicoloides weijiaensis — Xu, Zhou & Wang 2017: 11 , Figs. 2–5 .— Kou et al. 2018: 100.— Bochini et al. 2020: 712. — Schnabel et al. 2021: 32.

Spongicoloides novaezelandiae — Goy 2015: 310 , Figs. 9 –11 (in part).

Material examined: 1 female, 35.1 mm TL, NCPOR /HYD-IO/0018, Southwest Indian Ocean Ridge, Indian Ocean, R / V ‘MGS Sagar’ cruise MGS–26 (station: MGS 26C BD–15), 12 May 2019, 26° 28′ 10″ S, 67° 26′ 21″ E, 2358 m, benthic sledge, Coll. Baban Ingole, samples in 90% ethanol .

Measurements (mm): Female, PCL: 12.2, RCL: 15.4, TL: 35.1.

Description: Rostrum nearly horizontal, slightly overreaching basal article of antennular peduncle; rostral base triangular in dorsal view, armed with 9 dorsal, 2 ventral spines. Carapace with distinct cervical groove, anterolateral margin with scattered small spines; branchiostegal and pterygostomial regions smooth, and several spinules situated posterior to them, postorbital region armed with one short longitudinal row of spinules, groups of similar spinules also present on a posterior portion of cervical groove and rostrum. Antennal spine blunt. Eye s well developed, moderate in size; cornea globular, dark pigmented, broader than eyestalk, eyestalk armed with minute spines. Color in life: Body whitish, translucent; some intrathoracic organs visible.

Antennular peduncle reaches mid-length of antennal scale, the first article distinctly longer than both distal articles combined, with a blunt spine distolaterally, stylocerite small, subacutely pointed, second article longer than the distal article, bearing a single distal spinule on inner margin, distal article unarmed.

Antenna has stout basicerite, bearing four (right) or three (left) large spines at a distolateral angle, an additional four (right) or three (left) small spines on the ventrodistal margin, and two (right) or three (left) small spines on ventral surface proximally. Carpocerite overreaching first article of antennular peduncle. Antennal scale broad; twice as long as rostrum, 2.7 times as long as wide; lateral margin slightly concave, not setiferous, with ten (right) or twelve (left) spines; distolateral bifid spine slightly falling short of or just reaching rounded distal margin of lamella; inner margin convex; both inner and distal margins with long plumose setae; dorsal surface with single longitudinal carina. Basal article of antennal peduncle armed with three (right) or two (left) terminal spines laterally. Mandible strong, with well-developed 3-jointed palp; distal article densely setose on the margin, oval, subequal in length to intermediate article; molar and incisor processes separate. Molar surface smooth, tooth absent, incisor bearing with 2 strong stout distal teeth followed by 8 small sharp teeth on the mesial margin.

Maxillule has simple palp bearing a pair of terminal setae; distal endite broad, its mesial margin straight or truncates with simple setae and 10 stout spines; proximal endite suboval, narrowing or tapering distally. Maxilla has palp stout distally, tapering, bearing simple setae; distal and proximal endites bilobed; scaphognathite well developed with plumose setae. The branchial formula is summarized in Table 1 . First maxilliped has bi-jointed palp; distal article with one prominent spine; proximal article broad, 1.5 times of distal article in length; distal endite large, rounded anteriorly, proximal endite bilobed; exopod well developed; epipod large, subequally bilobed. Second maxilliped having endopod composed of seven articles; dactylus triangular, ~ 1.5 times as long as broad; propodus is subquadrate ~ 2 times of dactylus in length; carpus short, distally widening 0.5 times as long as propodus; long merus, 3 times as long as carpus; ischium not fused with basis with 0.2 times as long as merus; epipod oval, with rudimentary podobranch; exopod absent. Third maxilliped with 7-jointed endopod, slender, slightly overreaching mid-length of antennal scale in full extension; dactylus tapering distally; propodus 1.8 times as long as dactylus; carpus 1.1 times of propodal length; merus 1.7 times of carpal length; ischium subequal to merus; basis shortest, approximately 0.2 times length of ischium; coxa with tiny epipod; exopod absent.

First pereiopod is reaching distal margin of antennal scale; dactylus half as long as palm; subcylindrical palm, with some grooming setae; carpus longest, nearly 2.4 times as long as palm, distal part of flexor margin of carpus with a tuft of grooming setae, merus 0.7 times as long as carpus; ischium 0.5 times as long as merus; coxa and basis short, unarmed.

Second pereiopod is similar in shape to the first pereiopod, longer, overreaching distal margin of antennal scale by the length of chela; dactylus 0.4 times as long as palm; carpus 1.9 times as long as palm; merus 0.8 times as long as carpus; ischium 0.4 times as long as merus; coxa and basis short, unarmed.

Third pereiopod is the strongest and longest, overreaching distal margin of the antennal scale by the length of the chela; fingers terminating each in strongly curved, corneous claw, tips crossing, fixed finger with deep longitudinal concavity proximally, bearing single rounded tooth at nearly mid-length of cutting edge and with a short row of small teeth on the proximal cutting edge, distoventral margin without a row of teeth; dactylus 0.6 times of palm length, protruded at proximal 0.4 of length, with concavity on distal half portion; palm almost equal to merus in length, subcylindrical; propodus with some minute teeth present on distal half of flexor margin; carpus widening distally, nearly half as long as palm; merus of right third pereiopod unarmed, merus of left third pereiopod bearing minute tooth at approximately distal 0.2 of its length on flexor margin; ischium 0.9 times as long as carpus, flexor margin entirely smooth, distolateral margin also with similar teeth; basis and coxa short, unarmed.

Fourth pereiopod is overreaching distal margin of antennal scale by the length of dactylus and propodus, dactylus short, compressed laterally, biunguiculate, ventral unguis shorter than dorsal unguis, both demarcated, with some much smaller accessory teeth arising from bases of both ventral and dorsal ungues; propodus approximately 0.4 times length of carpus, armed with a single row of 11 or 12 movable spines on flexor margin; carpus longest; merus 0.8 times length of the carpus, ischium half-length of merus, unarmed; coxa and basis short and stout.

Fifth pereiopod is overreaching distal margin of antennal scale by dactylus and half-length of propodus.

Sixth thoracic sternite with paired triangular plates, the ventral surface curved in. Seventh and eighth sternites with bilobed prominences. Pleomeres glabrous. First somite short, uniramous, divided into two sections by distinct transverse carina, posterior section of pleuron rounded. Second to fourth pleura each bearing one articular knob; first to the third pleura broadly rounded ventrally, unarmed, and setose on ventral margin; fourth to sixth pleura each with several small posteroventral teeth.

First pleopod uniramous. Second to fifth pleopods biramous. Uropod with stout protopod, lateral margin terminating in two spines. Endopod and exopod each with a single weak dorsal carina. The lateral margin of the exopod is slightly convex with a row of 15 (left) or 16 (right) acute teeth, excluding a broad trilobed tooth on the distolateral angle. Endopod ovate, falling short of posterior margin of telson. Telson quadrangular, almost twice as long as broad, slightly constricted near the base, with two dorsolateral carinae prominent, lateral margin armed bearing 10 (right) or 12 (left) posteriorly directed spines; constricted part of each lateral margin with a single proximal submarginal spine, lateral marginal spines distinct. Setiferous posterior margin broadly rounded, with 13 spines.

Molecular data: A COI gene sequence of S. weijiaensis from the SWIOR has been deposited in Genbank (NCBI accession number MT806161 ). The pairwise genetic distances within species of Spongicoloides weijiaensis ranged from 0.02 to 0.03.

Distribution: The distribution of S. weijiaensis now extends from the North West Pacific, Madagascar, Indian Ocean (off Northern Australia), New Zealand, New Caledonia, Fiji, Tasmania (349–2380 m) to the seamount in the Mid Ocean Ridge sector of the Southwest Indian Ocean (2358 m).

Remarks: Throughout the species’ range, S. weijiensis has been found at depths of 349 to 2380 m; with 2380 m being the deepest record for any stenopodidean. Specimens from New Caledonia and Madagascar were identified as S. novaezelandiae but were shown to belong to S. weijiaensis ( Schnabel et al. 2021) . The Spongicoloides weijiaensis of Southwest Indian Ocean Ridge is morphologically similar to S. weijiaensis Xu, Zhou & Wang, 2017 and S. corbitellus Kou, Li & Gong, 2018 . Both specimens match the type description in nearly all aspects. Slight variation in the pigmented eyes, distal and proximal endites both bilobed compared to the original description is an additional large postorbital carapace spine, the first pleonite being more distinctly ridged ( Figure 4A ). A recent paper on New Zealand stenopodideans covers the differences between S. novaezelandiae and other species of Spongicoloides ( Schnabel et al. 2021) . Both our SWIR specimen and S. weijiaensis were found in the Euplectella sponge, S. corbitellus was collected from another euplectellid sponge of the genus Corbitellus ( Kou et al. 2018). Even though our specimen of Spongicoloides weijiaensis from SWIR is similar to S. iheyaensis Saito, Tsuchida & Yamamoto, 2006 , S. corbitellus , S. zhoui Zhao, Xu, Yang & Qiu, 2021 all from the Western Pacific Ocean, is distinguished by the differences in spination of carapace, sixth pleonal somite, and third pereiopod ( Figures 2 & 4 ).

Figures

FIGURE 1. Spongicoloides weijiaensis Xu, Zhou & Wang, 2017. Female (NCPOR/HYD-IO/0018) whole specimen, 35.1 mm., the Southwest Indian Ridge.

FIGURE 2. Spongicoloides weijiaensis Xu, Zhou & Wang, 2017. Female (NCPOR/HYD-IO/0018): A, carapace, lateral view, B, details of first to the sixth pleonal, C, telson and uropods, dorsal view D, fifth and sixth pleonal somite, telson, and uropods, dorsal view E, thoracic sternites, ventral view F, fifth and sixth pleonal somites, right lateral view.

FIGURE 3. Spongicoloides weijiaensis Xu, Zhou & Wang, 2017. Female (NCPOR/HYD-IO/0018):A & B, mandible dorsal & ventral view C, maxillule D, maxilla E, first maxillipeds F, second maxillipeds G, antenna H, antennules.

FIGURE 4. Spongicoloides weijiaensis Xu, Zhou & Wang, 2017. Female (NCPOR/HYD-IO/0018): A, third maxilliped B, first pereiopod C, second pereiopod D, third pereiopod E, fourth pereiopod F, dactylus and propodus of fifth pereiopod G, first pleopod H, second pleopod, left, mesial view H, second pleopod, right, mesial view.

FIGURE 5. The map shows the type locality of all known species of Spongicoloides spp. The red colour star indicates the new location of S. weijiaensis from the SWIOR

FIGURE 6. Phylogenetic trees of spongicolids based on the ML topology inferred from the gene fragments of mitochondrial COI. Bootstrap values of the ML analyses were placed at nodes, with dashes (–) indicating values below 50. Scale bars represent the number of substitutions per site.