Stenothoe ogumi, Alves & Neves & Johnsson, 2020

Alves, Jessika, Neves, Elizabeth & Johnsson, Rodrigo, 2020, Two new Amphilochida (Amphipoda: Amphilochidea) associated with the bioinvasive Tubastraea coccinea fromTodos-os-Santos Bay, Bahia State, Brazil, Zootaxa 4743 (1), pp. 21-34 : 27-32

Stenothoe ogumi sp. nov.

( Figs. 5-8 )

urn:lsid:zoobank.org:act:C21FE456-BC30-4787-A305-9996A3313F92

Examined material.

Holotype. Adult Male (dissected and drawn) 3.1 mm (UFBA 3567), Cavo Artemidi Shipwreck, TSB, Brazil (13°13’.31’’S, 38°31’.55’’W), associated with Tubastraea Tubastraea coccinea , 15m depth, 28 th November 2010, N. Menezes coll.

Paratypes. Adult male, 3.0 mm (UFBA 3568), Pecém Harbor, Ceará State, Brazil (39 o 50’00’’ W, 3 o 30’00’’ S), intertidal zone, 20 th May 2010 , Pachelle, PPG coll. Adult males, 2.0 – 3.0 mm (UFBA 3569), Salvador Harbor, TSB, Brazil (12°58’08.0”S 38°30’51.3”W), associated with Tubastraea and Tedania ignis , 10 m depth, 20 th September 2019 .

Etymology. The ship Cavo Artemidi shipwrecked in TSB, carrying more than 16,000 tons of crude iron. Cavo Artemidi stopped in Bahia to fuel. On the way out, the ship master did not accept the port service and was dragged by strong currents typical from the TSB.The species names refers to Ogum, a deity of iron, technology and war for some African religions common in Bahia State. By coincidence, the ship stranded in a locality called Santo Antônio bank. Considering the religious syncretism, Santo Antônio is a catholic saint, who corresponds to Ogum in Bahia state.

Diagnosis. Rounded big eyes. Maxilliped inner plate large and produced. Gnathopod 2 ischium subtriangular, propodus palm with rounded process near hinge of dactylus, proceeded by pronounced and acute process, dactylus robust, narrowing abruptly. Coxae 3 subrectangular with subparallel margins. Pereopod 6 and 7 with large merus. Telson with five lateral sample setae, the three anterior setae are longer than posterior ones.

Description. Head. Rostrum absent, ocular lobe triangular, eyes well developed and subovate ( Fig 5 ). Antenna 1 slightly longer than antenna 2, article 1 shorter than head, ventral margin with three small setae, article 2 about 0.3 times longer than article 1; flagellum with 14 articles ( Fig 5 ). Antenna 2 article 3 about 0.2 times longer than article 4, posterior margin beset with setae; flagellum with 11 articles ( Fig 5 ).

Mouthparts. Maxilliped outer plate rounded, short, about 0.3 the length of inner plate ( Fig. 6 ). Inner plate subrectangular, large, postero-lateral margin produced into an acute point, postero-facial margin with rounded process; articles 1 and 2 subquadrate and article 3 subrectangular; dactylus falcate beset with setae ( Fig. 6 ). Maxilla 1, palp article 1 subrectangular about twice longer than article 2 ( Fig. 6 ). Article 2 distally rounded with slender long setae; outer plate subrectangular with distal, stout setae; inner margin subrounded, with two apical small slender setae ( Fig. 6 ). Left mandibular palp absent; incisor with six robust teeth; accessory setae bifid ( Fig. 6 ).

Gnathopods. Gnathopod 1 and 2 dissimilar in size and shape. Gnathopod 1 subchelate, poorly developed ( Fig. 7 ). Coxa 1 subtriangular, anterior margin smooth and convex; basis subrectangular, posterior margin with three slender setae; merus, carpus and propodus reduced; merus distally setose, as long as ischium; carpus with distal projection. Propodus subrounded, palmar margin setose; dactylus as long as palm, without setae ( Fig. 7 ). Gnathopod 2, coxa 2 subrounded, anterior margin straight, posterior margin rounded, ventral margin beset with small setae. Basis slender subrectangular ( Fig. 7 ). Merus subquadrate, similar in length to ischium, posterior margin densely setose. Carpus as wide as propodus, posterior margin densely setose, anterodistal corner produced and acute ( Fig. 7 ). Propodus subovate, longer than the basis; palm densely setose, not defined, ornamented with a trapezoid process near hinge of dactylus and one hump between two excavations, palm continues serrated until it end ( Fig. 7 ).

Pereon. Pereopod 3, coxa 3 subrectangular, anterior and posterior margins subparallel; basis slender, posterior margin with few small setae.Isquium not larger than others segments. Merus as long as carpus, posterior margin with stout setae, posteroventral corner produced. Carpus subcilindrincal, posterior and anterior margin with small setae ( Fig. 7 ). Propodus 0.2 times longer than carpus, anterior margin setose; dactylus simple. Pereopod 4, coxa 4 subtriangular, well developed, about three times wider than coxa 3; basis strong and subcilindrical, as long as merus and carpus together ( Fig. 7 ). Merus posterodistal corner produced; carpus about 0.3 times longer than large, anterior margin setose ( Fig. 7 ). Propodus twice longer than carpus, posterior and anterior margin beset with small setae; dactylus simple ( Fig. 7 ).

Pereopod 5, coxa 5 trapezoid with anteriorly inflated. Basis ovate, slender with 4 small setae in each margin, merus posteroventral corner produced, posterior margin with stout setae ( Fig 8 ). Carpus 0.2 times shorter than merus, anterior margin beset with four setae; propodus twice longer than carpus; dactylus simple. Pereopod 6, coxa 6 trapezoid, anteriorly inflated; basis ovate, slender, as long as merus, anterior margin beset with 4 setae ( Fig 8 ). Merus inflated, about 0.3 times wider than carpus, posteroventral corner produced, posterior margin beset with stout setae; carpus 0.2 times shorter than merus, subrectangular, anterior margin with two small setae ( Fig 8 ). Propodus well developed more than twice longer than carpus, anterior margin beset with small setae, posterior margin scarcely setose; dactylus simple ( Fig 8 ). Pereopod 7 longer than pereopod 6; coxa 7 trapezoid, anterior margin inflated and rounded, posterior margin subquadrate; basis slender, with small setae; merus inflated, about 0.4 times wider than carpus, posteroventral corner strongly produced, posterior margin beset with small setae; carpus subrectangular, anterior margin with 4 small setae; propodus twice longer than carpus, posterior margin with 5 setae, anterior margin with 4 setae; dactylus simple ( Fig 8 ).

Urossome. Uropod 1 peduncle 0.2 times longer than rami, distal margin with two stout setae, distal corner with two smaller stout setae; rami subequal in length, leaf shaped; outer ramus with four stout setae, inner ramus with two stout setae ( Fig 8 ). Uropod 2 peduncle 0.5 times longer than rami, facial margin with three stout setae; outer ramus about 0.2 times longer than inner, with four stout setae, two of them longer and the other two setae smaller. Inner ramus with three stout setae ( Fig 8 ). Uropod 3 peduncle smaller than ramus; outer ramus 2-articulated; article 1 subrectangular with one stout setae, article 2 subtriangular with three setae. Telson fleshy, entire, with four stout setae in each margin ( Fig 8 ).

Remarks. The new species is similar to the Stenothoe valida complex by showing: (1) Male gnathopod 2 propodus palm almost straight with two processes near hinge of dactylus; (2) P5-7 merus enlarged. But the new species differs from S. valida due to: (1) the pronounced and developed maxilliped inner plate; (2) the palm of the gnathopod 2 propodus; (3) the subparallel margins of coxa 3; (4) the pereopods 6 and 7 with enlarged isquium and (5) the marginal setae of telson (Krapp-Shickel 2015). Stenothoe ogumi sp. nov. is also closely related to S. gallensis by having: (1) antenna 1 article 1 longer than the head; (2) coxa 2 somewhat excavated in hiperadult males and (3) male gnathopod 2 palm straight with long setae. Nevertheless, the new species shows: (1) rounded eyes bigger; (2) male gnathopod 2 propodus palm with trapezoid process and hump near hinge of dactylus (while S. gallensis has two acute humps); (3) uropod 3 peduncle shorter than outer ramus (while in S. gallensis it is as long as outer ramus) (Krapp-Schickel 2015). The new species also differs from S. marina by the shape of the palm of gnathopod 2 propodus. The new species seems to be closely related to Stenothoe sp. from Rio de Janeiro, described by Serejo (1998a), but it is different by the gnathopod 2 propodus palm processes and the shape of pereopods 6 and 7.

In South America, the association between stenothoids and cnidarians was recorded from the Chilean Patagonia, with the species S. bodoceropsis Krapp-Schickel, Haussermann & Vader 2015 living on the sea anemone Bodoceropsis platei Mc Murrich 1904 ( Krapp-Schickel et al. 2015). The present study reveals the first record of association between Stenothoe genus and the bioinvasive Tubastraea coccinea . Due the collect method, in which coral colonies are involved with plastic bags, removed with all contents and fixed in laboratory, was not possible to understand how this association occurs. Nevertheless, with the monitoring of this bioinvasive coral, it will be possible to understand how this species are related with the associated amphipods.

Figures

FIGURE 5. Stenothoe ogumi sp. nov. holotype (UFBA 3567) 3.1mm, Cavo Artemidi Shipwreck,15 m depth, Todos os Santos Bay, Brazil (13°13’31’’S, 38°31’55’’W). Scale bar: 1.0 mm.

FIGURE 6. Stenothoe ogumi sp. nov. holotype (UFBA 3567) 3.1mm, Cavo Artemidi Shipwreck, 15 m depth, Todos os Santos Bay, Brazil (13°13’.31’’S, 38°31’.55’’W). Scale bars: 0.1 mm

FIGURE 7. Stenothoe ogumi sp. nov. holotype (UFBA 3567) 3.1mm, Cavo Artemidi Shipwreck,15 m depth, Todos os Santos Bay, Brazil (13°13’31’’S, 38°31’55’’W). Scale bars: 0.5 mm (Gn1, Gn2, P3, P4); 0.3mm (palm).

FIGURE 8. Stenothoe ogumi sp. nov. holotype (UFBA 3567), 3.1mm, Cavo Artemidi Shipwreck, 15 m depth, Todos os Santos Bay, Brazil (13°13’31’’S, 38°31’55’’W). Scale bars: 0.5 mm.