Trischizostoma richeri Lowry & Stoddart, 1994

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 : 10-12

Trischizostoma richeri Lowry & Stoddart, 1994 (Fig. 5)

Trischizostoma richeri Lowry & Stoddart, 1994: 205 , figs. 46–48.

Material examined. REVIZEE Program, N. O. Thalassa col., stn. E­0510, 15º 48.503' S, 038º 36.265' W to 15º 47.383' S, 038º 36.154' W, 599 m, 12/ 06/ 2000; 1 female with oostegites, 61 mm, MNRJ 15138.

Type locality. Southwest Pacific Ocean, Loyalty Islands Basin, 21º 12.05' S, 166º 59.85' E, 2190 to 2205 m.

Diagnosis. Eyes well developed. Maxilliped palp longer than outer plate. Gnathopod 1 propodus oval; palm with 19 short robust setae and 3 pairs of long robust setae distally. Coxa 2 with anterior margin rounded. Gnathopod 2 carpus longer than ischium. Pereopod 3 basis 3 X of propodus length. Telson entire, subacute.

Description. Female, 61 mm (Fig. 5A). Rostrum reaching end of article 1 of peduncle of antenna 1. Eyes well developed. Antenna 1, article 1 of peduncle slightly longer than articles 2–3; callynophore present. Antenna 2, article 4 of peduncle slightly shorter than article 5. Mandibles with distal incisors; palp 3­articulate with lateral setae. Maxilla 1, inner plate 1/3 length of outer plate; outer plate with 8 distal setae. Maxilla 2, inner and outer plates subequal in length; outer plate with 5 lateral setae. Maxilliped, inner plate shorter than outer plate; palp with 4 articles and longer than outer plate.

Trischizostoma richeri Lowry & Stoddart, 1994 , female, 61 mm, MNRJ 15138. A, habitus; B, gnathopod 1; C, gnathopod 2; D, pereopod 3; E, telson. Scales bars: A, 5 mm; B, 1 mm; C–D, 2 mm; E, 1 mm.

Gnathopod 1 (Fig. 5B) strongly subchelate; coxa reduced and partially covered by coxa 2; propodus inverted, robust, oval; palm with stout setae in its extension and 3 pairs of longer setae distally. Gnathopod 2 (Fig. 5C), coxa with anterior margin rounded; carpus slightly longer than ischium; merus shorter than ischium; propodus less than half of carpus; dactylus reduced. Pereopod 3 (Fig. 5D), coxa longer than broad; basis 3 X of propodus length; carpus slightly longer than merus and with 7 distal setae; propodus more than twice length of dactylus and with 4 setae on posterior margin. Pereopod 4, coxa posteriorly excavated; basis longer than 2 X length of merus; carpus as long as merus and longer than propodus; dactylus as long as 1/3 propodus length. Pereopod 5, coxa broader than long; basis with posterior lobe; carpus slightly shorter than merus and with six setae on anterior margin; propodus longer than 2 X dactylus length. Pereopods 6 and 7, coxae broader than long; basis with posterior lobe; merus as long as carpus and propodus; carpus and merus with setae on anterior margin; propodus 3 X longer than dactylus.

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, subacute ( Fig. 4 E).

Distribution. Southwest Pacific Ocean, Loyalty Islands Basin; Southwest Atlantic Ocean, off Brazilian coast (15º S).

Remarks. Trischizostoma richeri was recently described and compared with other species of the genus ( Lowry & Stoddart, 1994). The Brazilian sample agrees with the type material in the diagnostic characters such as carpus of gnathopod 2 longer than ischium, basis of pereopod 3 3 X the propodus length and telson entire, subacute.

Figures

FIGURE 4. Trischizostoma raschi Boeck, 1861, female, 39 mm, MNRJ 151439. A, habitus; B, gnathopod 1; C, gnathopod 2; D, pereopod 3; E, telson; F, gnathopod 1 of juvenile, 4 mm, MNRJ 15143. Scales bars: A, 5 mm; B – D, 1 mm; E – F, 0.5 mm.