Triconia elongata Böttger-Schnack, 1999
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publication ID |
https://doi.org/ 10.1080/00222933.2013.771757 |
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persistent identifier |
https://treatment.plazi.org/id/551B87A1-B86B-3158-B82E-FDFD3CB5FED2 |
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treatment provided by |
Carolina |
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scientific name |
Triconia elongata Böttger-Schnack, 1999 |
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Triconia elongata Böttger-Schnack, 1999 Pacific form
( Figures 6–8 View Figure 6 View Figure 7 View Figure 8 )
Sampling locality
Northeast equatorial Pacific (10 ◦ 30 ′ N, 131 ◦ 20 ′ W, sampling depth 0–100 m).
Material examined
One female ( NIBRIV 0000245006) dissected and mounted on 10 slides.
Three females ( NIBRIV0000245007–9 ) dissected and mounted on 7 (one female) or 10 (two females) slides, respectively. All from Sampling locality collected on 21 August 2009 by D.J. Ham .
Other material examined
Two females ( NIBRIV0000245020 , -23) dissected and mounted on seven and nine slides, respectively. All from the Korea Strait (33 ◦ 44 ′ 50.50 ′′ N, 128 ◦ 15 ′ 39.02 ′′ E, sampling depth 0–110 m), collected on 7 October 2008 by K.H. Cho .
Description of female
Body length: 544 µm [traditional method: 504 µm] [traditional method, range: 476–504 µm, n = 5 individuals, based on specimens from the type locality; specimens from Korean waters fall into this size range].
Exoskeleton moderately chitinized, surface covered with numerous small pits (not figured), similar to T. pacifica . Prosome 1.6 times length of urosome, excluding caudal rami, about 1.5 times urosome length including caudal rami. P2-bearing somite without dorsoposterior projection in lateral aspect ( Figure 6B View Figure 6 ). Integumental pores on prosome as indicated in Figure 6A, B View Figure 6 . Pleural areas of P4-bearing somite with small pointed posterolateral corners. Integumental pores on urosomites ( Figure 6D View Figure 6 ) similar to T. pacifica .
Genital double-somite about twice as long as maximum width and 1.6 times as long as postgenital somites combined, with elongate flask-like form; largest width measured at anterior third, lateral margins slightly rounded, posterior two-thirds tapering gradually. Dorsal surface paired genital apertures located at about two-fifths of distance from anterior margin of genital double-somite and paired secretory pores posterior to genital apertures ( Figure 6C View Figure 6 ).
Anal somite slightly longer than wide; 1.5 times longer than caudal rami ( Figure 6C, D View Figure 6 ).
Caudal ramus ( Figure 6C View Figure 6 ) about 1.5 times as long as wide; length data of setae II– VII of holotype and two paratype females as shown in Table 1; range of variation of setal lengths relative to longest seta V as follows: II: 10–13%, III: 15–17%, IV: 47–52%, VI: 18–19%, VII: 35–42%, similar to T. pacifica , except for proportional length of seta IV smaller than in T. pacifica .
Antennule six-segmented ( Figure 7A View Figure 7 ). Armature formula as for T. pacifica .
Antenna three-segmented ( Figure 7B View Figure 7 ), relative lengths (%) of segments 40: 34: 26, similar to T. pacifica . Proximal endopodal segment ornamented with two or three rows of denticles along posterior inner margin. Distal endopodal segment with curved setae A–D similar in length, slender seta G about two-thirds as long as seta F, both setae shorter than seta D.
Labrum ( Figure 7G, H View Figure 7 ) with five to six large dentiform processes medially along distal margin of each lobe, processes differing in size and shape. Anterior surface ( Figure 7G View Figure 7 ) with spinular patch on either side of median swelling, lacking integumental pockets. Posterior surface ( Figure 7H View Figure 7 ) with group of three secretory pores on proximal part of each lobe and additional pair on midregion.
Mandible ( Figure 7C View Figure 7 ) similar to that of T. pacifica , except for dorsal blade (C) with large dentiform processes along half dorsal and entire distal margins.
Maxillule ( Figure 7D View Figure 7 ) similar to T. pacifica , even with respect to minor ornamentation details, such as spinulose ornamentation of element next to outermost one on outer lobe (arrowed in Figure 7D View Figure 7 ).
Maxilla ( Figure 7E View Figure 7 ) similar to that of T. pacifica .
Maxilliped ( Figure 7F View Figure 7 ) similar to T. pacifica , except for spiniform element on maxillipedal basis stout and stronger than in T. pacifica .
Swimming legs 1–4 ( Figure 8 View Figure 8 A–D) with armature as in T. pacifica . Intercoxal sclerites well developed (P1–P3) or narrow (P4), unornamented. Surface ornamentation on coxae and bases of P1–P4 as shown in Figure 8 View Figure 8 A–D. Coxa of P4 without tuft of setules on posterior surface. Bases with short (P1–P3) or long (P4) outer seta. Respective length differences between exopods and endopods similar to T. pacifica . Surface of exopodal and endopodal segments sparsely ornamented with secretory pores on posterior surface.
Exopods. Similar to T. pacifica , except for distal spine about equal in length to (P1, P2) or longer than (P3, P4) distal exopodal segment. Outer spine on P2 exp-2 shorter than in T. pacifica , not reaching beyond insertion of proximalmost spine on distal segment.
Endopods. Similar to T. pacifica , except for differences in length ratios of spines; length data of spines of holotype and two paratype females as shown in Table 1; length ranges of outer subdistal spine (OSDS) and outer distal spine (ODS) relative to distal spine are as follows: P2 enp-3, OSDS: 63–97%, ODS: 50–64%; P3 enp-3, OSDS: 41–63%, ODS: 33–41%, P4 enp-3, OSDS: 42–50%, ODS: 30–36%; outer distal spines relatively shorter than in T. pacifica , not reaching as far as tip of conical process in P2–P4, and outer subdistal spines not reaching as far as insertion point of outer distal spine in P2–P4.
P5 ( Figure 6C, D View Figure 6 ) with outer basal seta slightly shorter than in T. pacifica , reaching as far as genital apertures, about half the length of genital double-somite ( Figure 6D View Figure 6 ). Small free exopodal segment about as long as wide, outer exopodal seta about twice the length of inner one.
P6 ( Figure 6C View Figure 6 ) armed with one long spine and a minute spinule, which is discernible under the light microscope.
Male. Not found.
Remarks
The form variant from the Pacific strongly resembles the typical form of T. elongata Böttger-Schnack, 1999 from the Red Sea most morphometric characters, notably the elongate flask-like form of the female genital double-somite, and the length of the outer basal seta on P5, which is reaching as far as the genital apertures. Also, no significant morphometric differences between the two forms in the proportional spine lengths on the endopods of P2–P4 could be figured out, because the (single) values reported for the typical Red Sea T. elongata by Böttger-Schnack (1999) fell into the range of values observed for the three specimens of new form variant from the Pacific (cf. Table 1) and the range of variation of the typical form is not known so far. It may be noted, however, that some slight morphometric differences between the two forms were apparent, such as (1) the relative length of the outer distal spine on P4 enp-3, which does not reach as far as the tip of the conical process in the Pacific form, whereas this spine reaches as far as the tip of the cone in Red Sea T. elongata (cf. Böttger-Schnack 1999, fig. 29D), (2) the relative length of the outer spine on P2 exp-2 being relatively short in the Pacific form variant and not reaching beyond the insertion of the proximalmost spine on P2 exp-3, whereas this is the case in the typical form of T. elongata (Böttger- Schnack 1999, fig. 29B), and (3) the length ratio of antennary setae F and G, with seta G being about four-fifths the length of seta F in the Pacific T. elongata , whereas this seta is only three-fifths the length of seta F in T. elongata from the Red Sea.
The two form variants were furthermore separated by very few micro-structures, including (1) the spinular row either side of the median swelling on the anterior surface of the labrum being present in the Pacific form variant, but not in the typical form, and (2) the spinulose ornamentation of the seta on the outer allobasal margin of the maxilla, which is naked in the typical form. All other micro-characters, including those on the antennary coxobasis, the elements on the maxillule, and the outer basal seta on P5, were similar in both forms.
Triconia elongata is distributed in the entire Red Sea, including its northernmost extension, the Gulf of Aqaba ( Böttger-Schnack 1999; Böttger-Schnack et al. 2008). It has also been reported from the Mediterranean ( Böttger-Schnack and Schnack 2009) and in ecological studies from the north-east Indian Ocean ( McKinnon et al. 2008, 2013) and from Tosa Bay, southern Japan ( Nishibe et al. 2009). It remains to be determined, however, which of the two form variants were found in these areas, as the minor morphological differences separating the two forms had not been examined and / or might not have been detected in these studies, which did not provide detailed taxonomic information. Itoh (1997) described T. dentipes from the adjacent waters of Japan, however, the female genital double-somite of his specimen was figured as being quite elongate ( Itoh 1997, fig. 363, p. 987), which is more similar to T. elongata . Also, additional unpublished data (figures) of the swimming legs of T. dentipes sensu H. Itoh , kindly made available by H. Itoh to RBS, clearly show that the proportional endopodal spine lengths on P2–P4 are more similar to T. elongata than to T. dentipes , in particular with regard to the outer distal spine on P4 enp-3, which does not reach beyond the distal conical process in his specimens.
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