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Pseudeuphausia sinica Wang and Chen, 1963

Etymology: Pseudeuphausia - false Euphausia ; sinica - China

Eye: The eye is large in size (P. sinica eye & rostrum). The eye diameter : carapace length is about 0.20.

Peduncle of 1st Antenna: The 1st segment has a low, pectinate, anteriorly-directed fringe or lappet(P. sinica,). The 2nd segment has 7-10 distal setae which are directed anteriorly, adhering closely to the 3rd segment, with the tips converging mid-dorsally as a bundle. (See also the generic diagnosis in Higher Taxa.)

Mandible: A mandibular palp is lacking after the larval phases (P. latifrons vs. P. sinica).

1st Maxilla: A true larval exopod is present as well as the adult pseudexopod.

Rostrum: A rostrum is lacking but the frontal plate projects anteriorly, beyond the midpoint of the eye, as a rectangle (P. sinica eye & rostrum), the anterior margin of which appears somewhat concave in dorsal view and is medially depressed.

Carapace: Frontal plate as stated in generic diagnosis. There is no lateral carapace denticle.

Thoracic legs: Legs 1-5 are similar. The three distal segments of the 6th thoracic leg (endopod) of the male are, together, scarcely more than half as long as those segments of the 5th leg. In the female the 6th leg is only half as long as the 5th, but the 3rd and 4th joints form a semi-circle so as to support an ovisac, while the 3 terminal joints are extremely short.

Abdomen: The 6th segment of the abdomen has a short mid-dorsal posterior denticle.

Petasma: The distal end of the inner lobe is digitate (elongate) not triangular. The 3 to 4 curved spine-shaped processes on the inner lobe are variable in size. The median, auxiliary and setiferous lobes are as stated in generic diagnosis (P. sinica petasma).

Thelycum: Described by Guglielmo and Costanzo, 1983.

Length: Adults are 8-16 mm.

Comments: A key character used to separate the two species of this genus is the absence of a mandibular palp in adult P. sinica.

HORIZONTAL DISTRIBUTION
P. sinica has been mainly found in the coastal waters of the East China Sea and the southern part of the Yellow Sea. Casanova (1996) found 1 adult female at 23°39'S; 167°08'E near New Caledonia. Prior to 1963, presence/absence of a mandibular palp in Pseudeuphausia was rarely, if ever, noted. Hence, it is possible that occurrences of P. sinica have been confused with records of P. latifrons. Also, records of P. latifrons from the western Pacific based only on immature specimens may be questionable (P. sinica distribution).

VERTICAL DISTRIBUTION
P. sinica is a neritic species living in the shallow (<150 m) Yellow Sea and probably to similar depths in shelf and more offshore waters. Casanova (1996) found 1 adult female between 220-235 m.

LARVAE
See the development summary (P. sinica Table) for the stage descriptors and length in stage.

Metanauplius - (2 forms) (P. sinica A)

Carapace:
Shape - The carapace is very round and smooth.
Marginal spines - absent.

Calyptopis - (3 stages) (P. sinica B)

Carapace:
Shape - The carapace is smoothly rounded.
Marginal spines - absent
Postero-dorsal spine - absent
Lateral denticles - absent

Telson:
Postero-lateral spines - PL3 is longer than PL2.

Furcilia - (5 stages) (P. sinica C), (P. sinica D)

Eye: The eye is round.

Carapace:
Frontal plate / rostrum - The frontal plate is truncated with small acute antero-lateral angles. There is no conspicuous medial emargination.
Marginal spines - absent
Postero-dorsal spines - absent
Lateral denticles - A pair of denticles is present.
Mandible: The mandible is without an antero-lateral process, or palp, by F5. The absence of a mandibular palp characterizes the adult. (P. sinica E)

Thoracic legs: There is sequential development without elongate leg (s).

Abdomen:
Mid-dorsal spines - absent

Pleopods: There is a variety of forms in F2 and F3 with different levels of pleopod development. The common developmental pathways are 0 - 3' - 3"2' - 5" and 0 - 4' - 4"1' - 5".

Telson:
Postero-lateral spines - PL3 is longer than PL2.
Lateral spines - One pair of lateral spines is present.

Comments: In the furcilia stages, P. sinica appears to differ from the related species P. latifrons in the form of the frontal plate. In P. latifrons the anterior margin may be deeply and angularly emarginate with prominent antero-lateral projections. In P. sinica the anterior margin appears flat or only slightly concave.

Development
(P. sinica Table), development summary for the stage descriptors and length in stage.

Pictures
P. sinica, selected stages
P. sinica A [metanauplius]
P. sinica B [calyptopis 1-3]
P. sinica C [furcilia 1-2]
P. sinica D [furcilia 3-4]
P. sinica E [mandible]
key to larval illustrations

Pseudeuphausia sinica