Vercoia interrupta, Kim, 2004

Kim, Jung Nyun & Yoshihisa, Fujita, 2004, A new species of the genus Vercoia from Okinawa Island, Japan (Crustacea, Decapoda, Caridea, Crangonidae), with descriptions of its zoeal stages, Journal of Natural History 38 (16), pp. 2013-2031 : 2014-2021

publication ID	https://doi.org/ 10.1080/0022293032000140921
DOI	https://doi.org/10.5281/zenodo.4658463
persistent identifier	https://treatment.plazi.org/id/4C1D87E5-5347-FFF3-0DB5-FA61A22B44A5
treatment provided by	Carolina
scientific name	Vercoia interrupta
status	sp. nov.

Treatment

Vercoia interrupta View in CoL sp. nov.

( figures 1–7 View FIG View FIG View FIG View FIG View FIG View FIG View FIG )

Material examined

HOLOTYPE: spawning female (CL 4.0 mm), Cape Maeda , Okinawa Island, Ryukyu Islands, Japan, 8.5 m, coral rubble, 12 August 2000, scuba diving, coll. Y. Fujita, NFU 530-2-2500.

Adult morphology ( figures 1–3 View FIG View FIG View FIG )

Description. Body ( figure 1 View FIG ) small, robust; integument moderately hard, gibbous, sculptured with obtuse prominences, covered with short setae except for major carinae and tubercles; longitudinal carinae of both carapace and abdomen with flattened outer margin.

Rostrum ( figures 1 View FIG , 2A View FIG ) short and broad, 0.5 times as long as carapace, slightly over-reaching distal margin of antennular peduncle, depressed, slightly downward; posterior part widely flattened, moderately concave dorsally, weakly concave laterally; anterolateral lobes obliquely truncate, with concave distal margin; anterior part produced into narrow, elongate median process occupying distal 0.3 of rostral length, concave dorsally, with sharp ventral carina along entire rostral length, apex weakly pointed in dorsal view, slightly upturned in lateral view. Carapace ( figures 1 View FIG , 2A, B View FIG ) as long as deep, 0.7 times as long as wide, with broad smooth shield-like platform continued from rostrum in gastric region, bordered laterally by dorsolateral carinae; median carina on cardiac region subdivided into two subtriangular, anteriorly elevated carinae, anterior carina higher than posterior one, minute tubercle situated at front of anterior carina; dorsolateral carinae low, feebly irregularly sinuate, interrupted on posterior third by distinct notch; shieldlike platform limited posteriorly by two pairs of low oblique ridges broadly converging behind median carina near somewhat elevated posterior area of carapace; small submedian tubercles situated on sides of notch between anterior and posterior median carina. Orbits well developed (formed dorsally by proximal rostrum, posteriorly and ventrally by orbital margin of carapace, and anteriorly by stylocerite and antennular process), bearing inner row of setae on posterior and ventral orbital margins; antennal spine moderately strong; orbital cleft and longitudinal suture absent. Hepatic and branchial carinae long, anteriorly elevated, subdivided into two carinae, each posterior carina sinuous; hepatic carina anteriorly with bilobed process. Lateral area of anterior carapace with some short ridges or tubercles. Antennal region ( figure 2A View FIG ) with short, low, longitudinal carina just above branchiostegal lobe; anterior margin feebly convex. Anterolateral area of carapace ( figure 2A View FIG ) produced considerably in advance of antennal spine, slightly falling short of rostral apex, terminating in branchiostegal lobe supported by blunt, laterally expanded carina extending to level of mid-length of carapace. Anteroventral angle of carapace ( figure 2B View FIG ) with small pterygostomian spine, followed by swollen and setose part of incurved anteroventral margin of carapace. Ventrolateral area of carapace ( figure 2B View FIG ) anteriorly with shallow depression, posteriorly with some short ridges or tubercles. Ventral margin of carapace ( figure 2B View FIG ) irregularly sinuous with rounded setose lobes behind base of both third maxilliped and first pereopod; anterior lobe produced inferiorly into feebly hooked process with rounded tip.

Thoracic sternum deeply depressed, without any median structures, fused with precoxae of second pereopods, forming ventral plate with vertical anterior ridge terminating in strong, anteriorly directed tooth over-reaching articulation of first pereopods. Abdominal sternites broad, flat, anterior four sternites unarmed, fifth sternite with flattened posteromedian tooth; sixth sternite with smooth anterior sternal plate bearing submedian pair of teeth posteriorly.

Eye ( figure 2D View FIG ) with cornea well developed; eyestalk short, wider than cornea, swollen anterodorsally, with moderately large anteroventral tubercle, some fine spinules just anteriorly to anteroventral tubercle.

Antennule ( figure 2E View FIG ) broad, depressed, with peduncle falling slightly short of end of rostrum; proximal segment enlarged, as long as distal two segments combined, anterodorsal margin strongly elevated over articulation with second segment, bearing several setae, ventral surface without acute spine or longitudinal carina. Stylocerite enlarged, expanded anterolaterally, slightly falling short of distal margin of second segment; lateral margin angular, anterolateral margin slightly excavated, posterolateral margin setose; mesial margin convex; anterior margin rounded; ventral surface with transverse carina bearing rounded vertical lobe mesially. Second segment short, broad, bearing large setose lobe on mesial margin, anterolateral process blunt, falling short of end of distal segment. Distal segment with anterior margin somewhat produced forward. Upper flagellum stout, consisting of seven articles, distal five articles each with tuft of aesthetascs; lower flagellum slender, short, reaching distal margin of second article of upper flagellum, three-articulated.

Antenna ( figure 2F View FIG ) with basicerite stout, bearing elongate anterior process ascending over articulation with scaphocerite, anteroventral angle acute. Scaphocerite considerably stout, short, 0.4 times as long as carapace, exceeding end of upper antennular flagellum; blade broadly subtriangular with maximal width across proximal third, 0.7 times as wide as long; dorsal surface with longitudinal submedian ridge extending from basal articular knob with basicerite to level of distal third of scaphocerite length; lateral margin slightly convex, terminating distally in minute inconspicuous tooth. Carpocerite elongate, cylindrical, reaching mid-length of scaphocerite; flagellum slightly longer than two-thirds of carapace, consisting of about 17 articles.

Mandible ( figure 2G View FIG ) with molar process slender, armed with four teeth distally, terminal pair denticulate, subterminal pair much smaller than terminal one. Maxillule ( figure 2H View FIG ) with proximal endite ovate, with long marginal setae; distal endite with distal margin truncate, armed with five spines, anterior margin with row of long setae; palp slightly curved inward, bearing apical seta. Maxilla ( figure 2I View FIG ) with vestigial endites; endopod incurved, bearing some setae distolaterally; scaphognathite with anterior lobe wider than posterior one, posterior lobe with group of very long setae distally. First maxilliped ( figure 2J View FIG ) with endopod elongate, rounded distally, bearing marginal setae mesially; exopod longer than palp, caridean lobe curved ventrally with lateral margin setose, lash well developed; epipod large, feebly bilobed. Second maxilliped ( figure 2K View FIG ) pediform; propodus long, with long setae on mesial margin; dactylus short, subrectangular in shape, bearing patch of short setae on distal margin and four long spines proximally on mesial margin; exopod elongate, with well-developed lash; epipod well developed, curved outward. Third maxilliped ( figure 3A, B View FIG ) over-reaching distal margin of scaphocerite by ultimate segment, distal two segments depressed, broad, slightly concave on ventral surface; antepenultimate segment shorter than distal two segments combined, ventral margin bearing two deeply compressed lobes, distal lobe situated at distal quarter, hooked, produced anteriorly, proximal lobe ovate, deeper than distal lobe; penultimate segment as long as ultimate segments, 2.1 times as long as wide, lateral margin with row of setae and distolateral angle with two spines, mesial margin densely setose, bearing series of small spines; ultimate segment 2.4 times as long as wide, with minute apical spine slightly turned mesially, lateral margin convex bearing several tufts of spines distally and sparse setae proximally, mesial margin nearly straight, armed with many tufts of small spines along entire length; exopod reaching distal lobe of antepenultimate segment, lash well developed; well-developed arthrobranch present.

Abdomen ( figures 1 View FIG , 2C View FIG ) moderately sculptured, with irregular elevations and depressions; first somite without mid-dorsal carina; second to sixth somites each with broad mid-dorsal carina having rather deep groove on either side, that on second somite produced anteriorly as triangular process, that on third somite somewhat produced anterodorsally, that on fifth somite interrupted on mid-length by distinct notch, that on sixth somite produced posteriorly as blunt process; ventral margin of pleura of first, second and fifth somites rounded, that of third somite with blunt point, that of fourth somite weakly concave posteriorly; sixth somite broadened posteriorly, wider than long, slightly longer than deep, 0.5 times as long as carapace, posterolateral process not acute, posteroventral angle slightly produced posteriorly, but rounded.

First pereopod ( figure 3C, D View FIG ) considerably stout, subchelate, over-reaching distal margin of scaphocerite by half of palm; merus slightly excavated ventrally, with prominent proximal tubercle on ventral surface; carpus short, sculptured by two dorsal carinae and one mesial tubercle, with strong ventrolateral tooth; palm ( figure 3D View FIG ) 1.8 times as long as wide, cutting edge slightly oblique, lateral margin nearly straight, mesial margin sinuous, terminating distally in strong fixed finger. Second pereopod ( figure 3E, F View FIG ) stout, not chelate, reaching mid-length of chela of first pereopod; ischium strongly compressed laterally, broadened distally, ventral margin with row of long spines distally, distoventral angle terminating in acute tooth, dorsal margin with row of setae; merus compressed, broadened proximally, 2.2 times as long as wide, ventral margin with row of long spines, dorsal margin with row of setae; carpus broadened distally, 0.6 times as long as merus, ventral margin produced anteriorly in triangular lobe with several long and short setae; propodus ( figure 3F View FIG ) slightly compressed, 0.7 times as long as carpus, with strong spine at dorsodistal corner, dorsal surface with row of tufts of small spines; dactylus ( figure 3F View FIG ) stout, tapering distally to acute, distally curved unguis, with scattered small spines laterally. Third pereopod ( figure 3G View FIG ) very slender, over-reaching distal margin of scaphocerite by distal two segments; ischium long, dorsal margin with sparse short setae proximally; merus 0.6 times as long as ischium; carpus 1.7 times as long as merus, subdivided into two articles, basal article very short; propodus tapering distally, 0.5 times as long as carpus; dactylus styliform, 0.7 times as long as propodus, with patch of subterminal setae partly covered by thin lamellar hood. Fourth pereopod ( figure 3H, I View FIG ) stouter than third pereopod, nearly reaching distal margin of scaphocerite; ischium with sparse setae on dorsal margin; merus 1.3 times as long as ischium; carpus 0.5 times as long as merus; propodus 1.8 times as long as carpus, flexor margin with tuft of two spines distally and two small spines on distal half; dactylus ( figure 3I View FIG ) simple, compressed laterally, slightly curved, 0.4 times as long as propodus. Fifth pereopod ( figure 3J View FIG ) similar to fourth pereopod, reaching distal margin of basicerite of antenna; propodus with flexor margin bearing three small spines widely spaced and becoming long distally, mesial surface with two small spines distally.

Pleurobranchs of fourth to eighth thoracic somites inclined anteriorly.

Branchial formula as in table 1.

Pleopods with enlarged protopods facing outwards, with long marginal setae, appendices internae absent. First pleopod ( figure 3K View FIG ) with protopod relatively slender; endopod narrow, reaching level of half length of exopod; exopod broad. Second pleopod ( figure 3L View FIG ) with protopod strongly flattened, becoming narrow proximally; endopod somewhat curved outward, reaching slightly beyond distal margin of exopod; exopod very broad.

Telson ( figure 2C View FIG ) 1.4 times as long as sixth abdominal somite, 1.5 times as long as anterior width, 0.6 times as long as carapace, tapering to subtruncate tip bearing fine marginal setae and one pair of minute but acute posterolateral spines; dorsal surface with median groove bearing two pairs of small dorsal spines on pair of submedian carinae, each pair of spines situated at level of 0.4 and 0.7 of telson length, respectively.

Uropods ( figures 1 View FIG , 2C, L View FIG ) with rami broad, falling short of distal margin of telson. Endopod ( figures 1 View FIG , 2C View FIG ) with broad proximolateral lobe, forming marginal sinuation with concave medial part; dorsal surface with obscure median carina. Exopod ( figures 1 View FIG , 2L View FIG ) falling short of distal end of endopod, lateral margin feebly convex, bearing minute distolateral spine; mesial margin broadly rounded.

Colour in life. Body light brown in nature and dull white in laboratory; hepatic region of carapace with large crimson spot; abdomen with many light scarlet spots, especially pleura of second somite, and lateral surface of third somite with irregular moderately large spots; cornea greyish brown; antennular flagella dark brown; fourth and fifth pereopods orange, except for dactylus black, and proximal part of ischium and basis dark brown.

Habitat. The present specimen was collected on coral rubble by scuba diving at night. The shrimp apparently resembles a small piece of rubble, and its resemblance may make it cryptic on such a bottom.

Distribution. Cape Maeda, Okinawa Island, Japan, at depth of 8.5 m.

Etymology. The species name is derived from the Latin interruptus (~interrupted), referring to the characteristic interrupted mid-dorsal carina on the fifth abdominal somite.

Remarks. Vercoia interrupta sp. nov. has the following unique features readily distinguishing it from three congeners, V. gibbosa , V. socotrana and V. japonica : (1) the hepatic carina of the carapace is bilobed; (2) the mid-dorsal carina on the fifth abdominal somite is interrupted by a distinct notch; and (3) the ischium of the second pereopod bears a strong tooth at the distoventral corner. On the other hand, in the three congeners, the hepatic process is entire; the mid-dorsal carina on the fifth abdominal somite is entire; and the distoventral corner of the ischium of the second pereopod is unarmed.

The following key is useful only for mature females because no male specimen of any species has been taken.