Research Article |
Corresponding author: Chunsheng Wang ( wangsio@sio.org.cn ) Academic editor: Ingo S. Wehrtmann
© 2017 Peng Xu, Yadong Zhou, Chunsheng Wang.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Xu P, Zhou Y, Wang C (2017) A new species of deep-sea sponge-associated shrimp from the North-West Pacific (Decapoda, Stenopodidea, Spongicolidae). ZooKeys 685: 1-14. https://doi.org/10.3897/zookeys.685.11341
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A new species of the deep-sea spongicolid genus Spongicoloides Hansen, 1908 is described and illustrated based on material from the northwestern Pacific. Spongicoloides weijiaensis sp. n. was found inside a hexactinellid sponge, Euplectella sp., sampled by the Chinese manned submersible “Jiaolong” at depths of 2279 m near the Weijia Guyot, in the Magellan Seamount Chain. The new species can be distinguished from all congeneric species by several morphological features, involving gill formula, spination of the carapace, antennal scale, third pereiopod, telson and uropod, posteroventral teeth of the pleura, and dactyli of the fourth and fifth pereiopods. An identification key to the Pacific species of Spongicoloides is provided.
Hexactinellida , Magellan Seamount Chain, Spongicoloides , Weijia Guyot
The stenopodidean shrimp family Spongicolidae is a relatively small group of marine decapod crustaceans. Based on its gill formula and external morphological features, the genus Spongicoloides Hansen, 1908 represents the most derived group among spongicolid genera (
In May of 2016, during Dive 106 of the Chinese manned submersible “Jiaolong”, one specimen of a hexactinellid sponge, Euplectella sp. (Fig.
The type specimens were preserved in 80% ethanol and deposited in the Sample Repository of Second Institute of Oceanography (SRSIO), State Oceanic Administration, Hangzhou, China.
Marginal spines of the telson are counted as: spines on the lateral margin; spine on the posterolateral angle, at the termination point of the dorsolateral carina; and spines on the posterior margin. Postorbital carapace length (in mm) is abbreviated as cl in the text. In the laboratory, photographs were taken using a dissecting microscope (Zeiss Discovery V20) equipped with a camera (AxioCam ICc5). Line drawings were made with the aid of a drawing tube mounted on a LEICA M205 C stereomicroscope. Setae have been omitted from illustrations for clarity.
Holotype: ovigerous female, cl 11.1 mm, 13°01.01'N, 156°56.71'E, near Weijia Guyot, Magellan Seamount Chain, North West Pacific, depth: 2279 m, associated with hexactinellid sponge, coll. team of “Jiaolong” submersible, 1 May 2016, sample 37I-JL106-1, SRSIO16050001.
Paratype: male, cl 9.3 mm, same collection data as for holotype, sample 37I-JL106-2, SRSIO16050002.
Rostrum nearly horizontal, reaching to distal margin of basal article of antennular peduncle; rostral base triangular in dorsal view, each ventrolateral ridge armed with a minute spine. Carapace with distinct cervical groove; anterolateral margin with branchiostegal and pterygostomial spines, and several spinules situated posterior to them; postorbital region armed with one short longitudinal row of spinules; groups of similar spinules also present on posterior portion of cervical groove and rostrum. Second to fourth pleura each with one articular knob; first to third pleura broadly rounded and fourth to sixth pleura each with several posteroventral teeth. Telson quadrangular, with two conspicuous dorsolateral carinae each bearing 7–10 posteriorly directed spines. Eye devoid of dark pigment; eyestalk armed with minute spines. Lateral margin of antennal scale slightly concave, armed with 10–12 spines. Fixed finger of third pereiopod without row of small teeth on distoventral margin; ischium of third pereiopod with one row of 2–4 small teeth on flexor margin. Dactyli of fourth and fifth pereiopods biunguiculate primarily, bearing several much smaller accessory teeth arising from bases of ventral and dorsal ungues.
Rostrum (Fig.
Carapace (Fig.
Sixth thoracic sternite (Fig.
Pleomeres (Fig.
Telson (Fig.
Eyes (Fig.
Antennular peduncle (Fig.
Antenna with stout basicerite, bearing four (right) or three (left) large spines at distolateral angle, additional four (right) or three (left) small spines on ventrodistal margin, and two (right) or three (left) small spines on ventral surface proximally. Carpocerite overreaching first article of antennular peduncle. Antennal scale (Fig.
Mandible (Fig.
Maxillule (Fig.
Maxilla (Fig.
First maxilliped (Fig.
Second maxilliped (Fig.
Spongicoloides weijiaensis sp. n. Holotype female: A right eye, outer view B right antennule, dorsal view C right antennal scale, dorsal view D right mandible, inner view E right maxillule, outer view F right maxilla, outer view G left first maxilliped, outer view H left second maxilliped, inner view. Setae omitted. Scale bars 1 mm.
Third maxilliped (Fig.
First pereiopod (Fig.
Second pereiopod (Fig.
Third pereiopod (Fig.
Fourth and fifth pereiopods similar, moderately long and slender. Fourth pereiopod (Fig.
Fifth pereiopod (Fig.
Spongicoloides weijiaensis sp. n. Holotype female: A left third maxilliped, lateral view B left first pereiopod, lateral view C left second pereiopod, lateral view D left third pereiopod, lateral view E flexor margin of right third pereiopod chela, lateral view F left fourth pereiopod, lateral view G left fifth pereiopod, lateral view H dactylus of left fourth pereiopod, lateral view. Paratype male: I rostrum, lateral view J left third pereiopod, lateral view. Scale bars 1 mm.
All pereiopods with small and blunt protrusions on proximal parts of ischial flexor margins.
First pleopod (Fig.
Uropod (Fig.
Holotype female carrying thirteen eggs (Fig.
Spongicoloides weijiaensis sp. n. Holotype female: A thoracic sternites, ventral view C first pleopod, lateral view D second pleopod, lateral view E eggs, outer view. Paratype male: B thoracic sternites, ventral view F second to sixth pleonites, showing spine of fifth sternite, lateral view.
Rostrum (Fig.
The specific name, weijiaensis, refers to the type locality, the Weijia Guyot, part of the Magellan Seamount Chain in the northwestern Pacific.
Body whitish, translucent; corneas, some intrathoracic organs and eggs pale yellow.
One of the most important taxonomic features of species assigned to Spongicoloides is the branchial formula. Although some gills are rather fragile and easily detachable structures, and their development may be variable (rudimentary, simple or well-developed), the total number of gills is still one of the first and main characters to examine when one is dealing with Spongicoloides.
Spongicoloides weijiaensis sp. n. shares the presence of two arthrobranchs on the third maxilliped and first through fourth pereiopod with Spongicoloides novaezelandiae Baba, 1979 from Chatham Rise east of New Zealand, S. hawaiiensis Baba, 1983 from Hawaii, and S. iheyaensis Saito, Tsuchida & Yamamoto, 2006 from southern Japan (
The other five species of Spongicoloides can be distinguished in having substantial differences in the gill formulae, such as the third maxilliped bears a single arthrobranch in S. evolutus (Bouvier, 1905a) and the first through fourth pereiopod each bear a single arthrobranch in S. galapagensis Goy, 1980, S. inermis (Bouvier, 1905b), S. profundus Hansen, 1908 and S. tabachnicki Burukovsky, 2009.
The new species can be separated from S. novaezelandiae by the fourth pleuron bearing several minute teeth on the posteroventral margin (vs fourth pleuron broadly rounded in S. novaezelandiae); the flexor margin of the third pereiopod ischium armed with a row of 2-4 small teeth (vs unarmed in S. novaezelandiae); the second maxilliped with a single arthrobranch (vs with paired arthrobranchs in S. novaezelandiae); and the fourth and fifth pereiopod dactyli with accessory teeth at the bases of the ungues (vs absent or at most with small angle in S. novaezelandiae) (cf.
The new species can be also distinguished from S. hawaiiensis, e.g. by the carapace bearing groups of spinules posterior to the rostrum, orbits, cervical groove and pterygostomian angle (vs almost spineless in S. hawaiiensis); the more numerous spines on the lateral and posterior margins of the telson and the lateral margin of the antennal scale; the flexor margin of the third pereiopod ischium armed with some small teeth (vs unarmed in S. hawaiiensis); and the dorsal surface of the antennal scale and uropodal exopod each with a single mesial or submesial longitudinal carina (vs with two longitudinal carinae in S. hawaiiensis) (cf.
Spongicoloides weijiaensis sp. n. differs from S. iheyaensis by the sixth pleonite unarmed dorsally (vs armed with one spine or a longitudinal row of small spines on dorsal midline in S. iheyaensis); the fixed finger of the third pereiopod unarmed on distoventral margin (vs bearing a short row of small teeth on the distoventral margin in S. iheyaensis); the third pereiopod ischium armed with a row of 2-4 small teeth on flexor margin (vs unarmed in S. iheyaensis); the dorsal surface of the antennal scale and uropodal exopod with one mesial or submesial longitudinal carina (vs with two longitudinal carinae in S. iheyaensis); and the ovigerous female with much smaller number of eggs (13 eggs in holotype female of S. weijiaensis sp. n. vs 229 eggs in holotype female of S. iheyaensis) (cf.
1 | Third maxilliped and first through fourth pereiopod each with single arthrobranch; propodus and ischium of third maxilliped armed with spines on mesial margins; dorsal median carina of uropodal endopod with a single spine | S. galapagensis Goy, 1980 |
– | Third maxilliped and first through fourth pereiopod each with two arthrobranchs; propodus and ischium of third maxilliped unarmed on mesial margins; dorsal median carina of uropodal endopod unarmed | 2 |
2 | Sixth pleonite armed with one spine or longitudinal row of small spines on midline; fixed finger of third pereiopod armed with several (3-9) teeth on distoventral margin | S. iheyaensis Saito, Tsuchida & Yamamoto, 2006 |
– | Sixth pleonite unarmed on midline; fixed finger of third pereiopod unarmed on distoventral margin | 3 |
3 | Carapace with spinules on postrostral and postorbital regions; third pereiopod ischium with row of 2-4 small teeth on flexor margin | S. weijiaensis sp. n. |
– | Carapace without spinules on postrostral and postorbital regions; flexor margin of third pereiopod ischium unarmed | 4 |
4 | Carapace with scattered spinules on anterolateral region; third pereiopod ischium with prominent process on distoventral margin; posterior margin of telson with eight spines | S. novaezelandiae Baba, 1979 |
– | Carapace without scattered spinules on anterolateral region, third pereiopod ischium without distoventral process; posterior margin of telson with three spines | S. hawaiiensis Baba, 1983 |
We are very grateful to all the scientists and crew of the R/V “Xiangyanghong 9” and the team of the submersible “Jiaolong” for their help in the collection of interesting deep-sea material. We sincerely thank Dr Joseph W. Goy (Department of Biology, Harding University, USA), who helped us to check morphological characters of the new species and provided valuable guidance in the taxonomy of stenopodidean shrimps. We express our appreciation to Dr Tomoyuki Komai (Natural History Museum and Institute, Chiba, Japan), Dr Mary K. Wicksten (Department of Biology, Texas A&M University, USA) and the anonymous reviewer for commenting upon and improving the manuscript patiently and meticulously. We specially acknowledge Dr Dongsheng Zhang (SIOSOA) for helping sequence the 16S rRNA and COI barcoding gene segments of the new species. This study was supported by the National Basic Research Program of China (No. 2015CB755901), foundation of China Ocean Mineral Resources R & D Association (No. DY125-13-E-01), Scientific Research Fund of the Second Institute of Oceanography, SOA (No. JG1613), and the National Natural Science Foundation of China (NSFC) (No. 41606155).