Nematocarcinus machaerophorus Burukovsky, 2003

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 machaerophorus Burukovsky, 2003

Nematocarcinus machaerophorus : Burukovsky (2003), p. 116-118, fig. 33; Burukovsky (2004), p. 1183-1184; Burukovsky (2006b), p. 1065, fig. 3a-d; Burukovsky (2012), p. 134-136, fig. 47.

Materials

Type status: Other material. Occurrence : individualCount: 1; sex: female; lifeStage: adult (CL 23. 5 mm); reproductiveCondition: ovigerous; establishmentMeans: wild; preparations: damaged animal (ETOH), DNA extract; disposition: in collection; associatedSequences: OP093564, OP089181 ; occurrenceID: 9466BC66-651D-5D94-B040-34418CAA2A52; Taxon : scientificNameID: urn:lsid:marinespecies.org:taxname:586809; scientificName: Nematocarcinus machaerophorus Burukovsky , 2003; order: Decapoda ; family: Nematocarcinidae ; genus: Nematocarcinus ; specificEpithet: machaerophorus; scientificNameAuthorship: Burukovsky , 2003; taxonomicStatus: accepted; Location : higherGeography: northwestern Pacific ; waterBody: Pacific Ocean ; country: China; countryCode: China /CN; locality: the South China Sea ; verbatimDepth: 811-849 m; verbatimCoordinates: 15.51795°N, 110.95654°E; Identification: identifiedBy: Zhibin Gan; dateIdentified: 06/01/2022; identificationReferences: Burukovsky, 2003, 2004, 2006b, 2012; Event: samplingProtocol: Agassiz trawl; eventDate: 14/06/2020; fieldNumber: St. AT-S59; fieldNotes: Coll. Xu; Record Level: language: en; collectionID: MBM189206; institutionCode: Marine Biological Museum ofthe Chinese Academy of Sciences (MBM)

Description

Body moderately slender, integument hard, surface smooth. Rostrum damaged, remaining part nearly horizontal, dorsal margin armed with nine articulated teeth, including four on rostrum proper and five on carapace posterior to orbital margin, space between teeth increasing distally; ventral margin unarmed at remaining part (Fig. 4 A). Antennal and pterygostomian teeth well developed (Fig. 4 A).

Eyes normally developed; cornea wider than eye stalk.

Third maxilliped not reaching distal end of scaphocerite; ultimate segment 0.75 times as long as penultimate segment, not markedly broadened at middle, without apical spinule; antepenultimate segment subequal in length to distal two segments combined, armed with six spines on lateral margin and two distal spines; exopod falling short of distal margin of antepenultimate segment.

All pereiopods lost.

Posterodorsal margin of third pleomere rounded, continuation of its sides forming an angle slightly larger than 120° (Fig. 4 B). Pleura of fifth pleomere without bump on inner sides, terminating by a sharp tooth (Fig. 4 C).

Ventral organ at sixth pleomere formed by two single rows of long plumose setae and two spots; setae rows cambered laterally, extending to front of spots (Fig. 4 D); spots located on a high tubercle-blister, about 1.98-2.01 times as long as wide, distance between spots slightly larger than a half of a spot width (Fig. 4 D).

Telson damaged.

Distribution

Previously only known from type locality, the Yeiao and Ua Pou Islands (Marquesas Islands Archipelago, central Pacific) at depths of 1000-1100 m ( Burukovsky 2003, Burukovsky 2004, Burukovsky 2006b, Burukovsky 2012). Presently recorded from the South China Sea, north-western Pacific.

Remarks

Species of Nematocarcinus are difficult to identify, not only because of their excessive morphological diversity, but also because of the fragility of the pereiopods and rostrum, which are usually damaged during collection. Burukovsky (2000f), Burukovsky (2000g) and Burukovsky (2012) proposed using the features of the tergum of the third pleomere, pleura of the fifth pleomere, distoventral organ of the sixth pleomere, the rostrum and the telson as key diagnostic characteristic markers. This greatly improved the taxonomy of Nematocarcinus . The present specimen had damaged rostrum and telson that could not be identified through morphology. Fortunately, DNA barcoding provides another efficient way to validate a species. BLAST results indicated a 98.57% match in the COI sequence between the present specimen (OP093564) and the holotype of N. machaerophorus Burukovsky, 2003 (KP759445, MNHN-IU-2011-5629), in which only seven nucleotide sites differed. The COI genetic distance between present specimen and the holotype of N. machaerophorus (KP759445, MNHN-IU-2011-5629) is 1.8%. The 16S rRNA sequence (OP089181) was identical to that of the holotype of N. machaerophorus (KP725571, MNHN-IU-2011-5629). Furthermore, the preserved characteristics of the present specimen, such as the tergum of the third pleomere, the pleura of the fifth pleomere and the distoventral organ, match those of N. machaerophorus , particularly the distoventral organ located on a high tubercle blister of the sixth pleomere. Its setae rows and spots exhibit a similar arrangement to that of the holotype ( Burukovsky 2004, Burukovsky 2006b, Burukovsky 2012).

Figures

Figure 4. Nematocarcinus machaerophorus Burukovsky, 2003, MBM 189206, female. A anterior part of carapace and cephalic appendages, lateral view; B pleomere 3 - 4, dorsal view; C right pleura of fifth pleomere, lateral view; D sixth abdominal somite, ventral view. Scales: 1.0 mm.