Nematocarcinus evansi Burukovsky, 2000

Gan, Zhibin & Li, Xinzheng, 2022, First records of three Nematocarcinus species (Crustacea, Decapoda, Nematocarcinidae) in the deep-waters of the north-western Pacific, Biodiversity Data Journal 10, pp. 95101-95101 : 95101

Nematocarcinus evansi Burukovsky, 2000

Nematocarcinus evansi : Burukovsky (2000e), p. 1291, fig. 2; Burukovsky (2003), p. 85-87, fig. 23; Burukovsky (2012), p. 107-108, fig. 34.

Materials

Type status: Other material. Occurrence : individualCount: 1; sex: female; lifeStage: adult (CL 29.5 mm); reproductiveCondition: non-reproductive; establishmentMeans: wild; preparations: damaged animal (ETOH), DNA extract; disposition: in collection; associatedSequences: OP093562, OP093563 ; occurrenceID: C836B536-48AB-5983-9712-5D897E11FE32; Taxon : scientificNameID: urn:lsid:marinespecies.org:taxname:514308; scientificName: Nematocarcinus evansi Burukovsky , 2000; order: Decapoda ; family: Nematocarcinidae ; genus: Nematocarcinus ; specificEpithet: evansi; taxonRank: species; scientificNameAuthorship: Burukovsky , 2000; nomenclaturalCode: ICZN; taxonomicStatus: accepted; Location : higherGeography: northwestern Pacific ; waterBody: Pacific Ocean ; country: China; countryCode: China /CN; locality: the South China Sea ; verbatimDepth: 734-736 m; verbatimCoordinates: 15.72057°N, 110.77073°E; Identification: identifiedBy: Zhibin Gan; dateIdentified: 12/12/2021; identificationReferences: Burukovsky 2000e, 2003, 2012; identificationRemarks: another specimen (MBM189205, female, CL 17.5 mm), Nematocarcinus undulatipes Spence Bate, 1888, was collected at the same sampling station and compared with Nematocarcinus evansi Burukovsky, 2000; Event: samplingProtocol: Agassiz trawl; eventDate: 13/06/2020; fieldNumber: St. AT-S58; fieldNotes: Coll. Xu; Record Level: language: en; collectionID: MBM189203; institutionCode: Marine Biological Museum of the Chinese Academy of Sciences (MBM)

Description

Body robust, integument hard, surface smooth, shiny. Rostrum straight, slightly over-reaching distal end of antennular peduncle, reaching mid-length of scaphocerite; 0.34 times as long as carapace (Fig. 1 A and Fig. 2 A); dorsal margin armed with seven articulated teeth (an additional small tooth under proximal fifth tooth), including four on rostrum proper and three on carapace posterior to orbital margin; space between teeth increasing distally, distance from apex to distal tooth longest, about one-third of its length; ventral margin armed with one small subdistal tooth (Fig. 1 A). Antennal and pterygostomian teeth well developed.

Eyes normally developed; cornea wider than eye stalk.

Third maxilliped not reaching distal end of scaphocerite; ultimate segment 0.71 times as long as penultimate segment, not markedly broadened at middle, armed with four apical spinules; antepenultimate segment shorter than distal two segments combined, armed with 4-6 spines on lateral margin and two distal spines; exopod slightly shorter than antepenultimate segment.

First pereiopod slender, over-reaching the end of scaphocerite by distal half-length of carpus. Ischium of first pereiopod with four ventrolateral spines, merus unarmed; ischium of third pereiopod with one distolateral spine. Other pereiopods lost.

Posterodorsal margin of third pleomere rounded, continuation of its sides forming an angle of about 120° (Fig. 1 B). Pleura of fifth pleomere without bump on inner sides, terminating by a sharp tooth curved downwards in left side (Fig. 1 C), a small spine present under distal tooth on the right side (Fig. 1 D).

Ventral organ at sixth pleomere formed by two single rows of long plumose setae and two spots; setae rows cambered in front half and nearly parallel in distal half, extending to front of spots; spots 1.96-2.01 times as long as wide, distance between spots about 1.04 times spots width (Fig. 1 E).

Telson armed with nine pairs of dorsolateral spines, two pairs of distal spines and a pair of accessory spines in middle of telson (Fig. 1 F).

Colour, bright red (Fig. 2 A).

Distribution

Previously only known from the waters of south-western Australia (20°16'03''S, 113°13'05''E), the Indian Ocean, at depths from 913-916 m ( Burukovsky 2000e, Burukovsky 2012). Presently recorded from the South China Sea, the Pacific Ocean.

Remarks

The present material is consistent with the original description of N. evansi ( Burukovsky 2000e, Burukovsky 2012), especially the features of the rostrum and distoventral organ. Small differences were also observed: the South China Sea sample has a sub-spine under the proximal fifth tooth of the rostrum and distal tooth of the right pleura of the fifth pleomere. However, these should be considered individual variations. A slender specimen (MBM189205, female, CL 17.5 mm) was collected at the same sampling station, but its rostrum was broken (Fig. 1 G-H Fig. 2 B). It closely resembles N. evansi apart from its distoventral organ, which is most like that of N. undulatipes Spence Bate, 1888. According to Burukovsky (2012), the only difference between N. evansi and N. undulatipes is that the latter has the distance between spots of a half-spot width and the unparallel setae rows (distal part) of the distoventral organ in the sixth pleomere. The slender specimen was consistent with this and, thus, was identified as N. undulatipes , which was previously recorded in the South China Sea ( Liu 2008). Furthermore, the COI genetic distance between these two specimens is 13.6%, only slightly less than the average genetic divergence of genus Nematocarcinus (16.0%, n = 20). Partial sequences of the COI and 16S rRNA genes of these two samples were deposited in GenBank for future research (OP093562, OP093563, OP089179, OP089180).

Figures

Figure 1. Nematocarcinus evansi Burukovsky, 2000, MBM 189203, female (A-F) N. undulatipes Spence Bate, 1888, MBM 189205, female (G-H). A anterior part of carapace and cephalic appendages, lateral view; B pleomere 3 - 4, dorsal view; C left pleura of fifth pleomere, lateral view; D right pleura of fifth pleomere, lateral view; E sixth abdominal somite, ventral view; F telson, dorsal view; G rostrum, lateral view; H distoventral organ, ventral view. Scales: 1.0 mm.

Figure 2. Photographs: A Nematocarcinus evansi Burukovsky, 2000, MBM 189203, female; B Nematocarcinus undulatipes Spence Bate, 1888, MBM 189205, female; C Nematocarcinus exilis (Spence Bate, 1888), SRSIO 20080316, female; D Nematocarcinus exilis (Spence Bate, 1888), SRSIO 20080316, male.