Trischizostoma raschi Boeck, 1861

Freire, Pablo R. & Serejo, Cristiana S., 2004, The genus Trischizostoma (Crustacea: Amphipoda: Trischizostomidae) from the Southwest Atlantic, collected by the REVIZEE Program, Zootaxa 645, pp. 1-15 : 8-10

publication ID

https://doi.org/ 10.5281/zenodo.158742

publication LSID

lsid:zoobank.org:pub:90A43524-8A17-46D6-8F32-8B5EED96B83C

DOI

https://doi.org/10.5281/zenodo.6271766

persistent identifier

https://treatment.plazi.org/id/03A01220-6C02-807F-D033-FD9C9244FC4A

treatment provided by

Plazi

scientific name

Trischizostoma raschi Boeck, 1861
status

 

Trischizostoma raschi Boeck, 1861 ( Fig. 4 View FIGURE 4 )

Trischizostoma Raschii Boeck, 1861: 631 .

Trischizostoma Raschi — Sars, 1895: 31, pl. 120.

Trischizostoma nicaeense — Stebbing, 1906: 13 (partim); Barnard & Karaman, 1991: 536, figs. 87D, 89 O, 90B, 91H, 92H, 93C, 95U (not T. nicaeense (Costa, 1853)); Gurjanova, 1951: 156, fig. 31 (not T. nicaeense (Costa, 1853)).

Trischizostoma raschii — Sexton, 1908: 385, pl. 17, fig. 13; pl.18, 19, fig. 2–11; pl. 20; pl. 21, fig. 1–13, 15–18.

Trischizostoma raschi — Diviacco & Ruffo, 1989: 559, fig. 383.

Material examined. REVIZEE Program, R/V Thalassa col., stn. E­0507, 15º 08.595' S, 038º 40.638' W to 15º 07.158' S, 038º40.542' W, 1026 m, 1 ovigerous female, 39 mm, MNRJ 15139. Stn. E­0535, 19º 59.936' S, 039º 38.657'W to 19º 56.087'S, 039º 35.408 W, 1002 m, 1 ovigerous female, 29 mm, MNRJ 19251. Stn. E­0523, 19º 42.569'S, 038º 32.030' W to 19º 42.685'S, 038º 36.961' W, 922 m, 1 ovigerous female, 27 mm, MNRJ 15145.

Type locality. North Atlantic, off Norway coast.

Diagnosis. Eyes well developed. Maxilliped palp with 4 articles and longer than outer plate. Gnathopod 1 propodus of triangular. Coxa 2 with anterior margin acute. Coxa 4 posteriorly excavated, with postero­ventral lobe. Telson emarginate.

Description. Female, 29 mm ( Fig. 4 View FIGURE 4 A). Rostrum reaching halfway of first article of antenna 1 peduncle. Eyes well developed. Antenna 1, article 1 of peduncle more than twice length of articles 2–3 together; flagellum with 9 articles; callynophore present. Antenna 2, article 5 slightly longer than article 4. Mandibles with distal incisors; palp 3­ articulate with marginal setae. Maxilla 1, inner plate 1/3 of outer plate length; outer plate with 8 distal setae and palp attached medially. Maxilla 2, inner plate slightly shorter than outer plate; outer plate with 3 lateral setae. Maxilliped, inner plate shorter than outer plate; palp with 4 articles and longer than outer plate.

Gnathopod 1 strongly subchelate ( Fig. 4 View FIGURE 4 B); coxa reduced and partially covered by coxa 2; propodus inverted, robust, triangular; palm slightly convex with stout setae along all its extension and 3 pairs of longer setae distally. Gnathopod 2 ( Fig. 4 View FIGURE 4 C), coxa subtriangular, with acute anterior margin; basis 2 X length of ischium, which is longer than carpus; dactylus reduced. Pereopod 3 ( Fig. 4 View FIGURE 4 D), coxa longer than broad; basis longer than merus; carpus as long as propodus; propodus and dactylus with minute setae on posterior margin.

Pereopod 4, coxa posteriorly excavated, with postero­ventral lobe; basis as long as merus; carpus and propodus subequal in length. Pereopods 5–7, coxae broader than long; basis with posterior lobe; carpus and merus subequal in length; dactylus half length of propodus.

Uropods 1 and 2, peduncle subequal to outer ramus; inner ramus slightly longer than outer ramus. Uropod 3, peduncle slightly shorter than half of outer ramus; inner and outer rami subequal in length; outer ramus 2­articulate, with basal article 5 X length of distal article. Telson entire, emarginate ( Fig. 4 View FIGURE 4 E).

Distribution. North Atlantic, Mediterranean Sea and Southwest Atlantic, off Brazilian coast (15º to 19º S).

Remarks. Trischizostoma raschi is similar to T. denticulatum , T. circulare , T. longirostrum , T. richeri , T. nicaeense and T. crosnieri in having the maxilliped palp longer than the outer plate and the telson entire. It differs from T. nicaeense (see Sexton, 1908), T. circulare , T. longirostrum and T. richeri in the shape of the anterior margin of coxa 2, which is acute in T. raschi and rounded in other species. It also differs from T. denticulatum in the triangular propodus of gnathopod 1, which is subquadrate in the latter.

Seemingly, T. raschi is very close to T. crosnieri in the acute anterior margin of coxa 2 and the triangular propodus of gnathopod 1. Lowry & Stoddart (1993) indicated that the number of stout setae on the palm of the gnathopod 1, the posterior lobe of the basis of pereopod 6 and shape of the telson as diagnostic characters between these species. However, the conspicuous distinction is in the telson, which is entire in T. raschi and cleft in T. crosnieri.

Some characters may change according to the development of the individual. Juveniles of T. raschi , removed from a mature female, have the telson cleft, a relative longer propodus of gnathopod 1 and the palm without setae when compared with the adult forms ( Fig. 4 View FIGURE 4 F). Detailed examination in some juveniles (30 specimens) suggests that the setae on the palm of gnathopod 1 appeared at the same time and not by addition in each distinct molt.

MNRJ

Museu Nacional/Universidade Federal de Rio de Janeiro

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Amphipoda

Family

Lysianassidae

Genus

Trischizostoma

Loc

Trischizostoma raschi Boeck, 1861

Freire, Pablo R. & Serejo, Cristiana S. 2004
2004
Loc

Trischizostoma raschi

Diviacco 1989: 559
1989
Loc

Trischizostoma raschii

Sexton 1908: 385
1908
Loc

Trischizostoma nicaeense

Barnard 1991: 536
Gurjanova 1951: 156
Stebbing 1906: 13
1906
Loc

Trischizostoma

Sars 1895: 31
1895
Loc

Trischizostoma Raschii Boeck, 1861 : 631

Boeck 1861: 631
1861
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