Species of Excorallana ( Isopoda , Corallanidae ) from northern and northeastern Brazil , with description of a new species , E xcorallana lemoscastroi sp . nov .

Several Brazilian specimens of the genus Excorallana Stebbing, 1904, were revised based on material deposited in the carcinological collection of the Museu de Oceanografia Prof. Petrônio Alves Coelho, Universidade Federal de Pernambuco, Recife, Brazil. The material examined was collected during oceanographic expeditions off northern and northeastern Brazil between 1965 and 2000. Seven species were identified: Excorallana bicornis Lemos de Castro & Lima, 1971; Excorallana costata Lemos de Castro, 1960; Excorallana oculata (Hansen, 1890); Excorallana richardsoni Lemos de Castro, 1960; Excorallana subtilis (Hansen, 1890); Excorallana warmingii (Hansen, 1890); and a putative new species, Excorallana lemoscastroi sp. nov. The new species was found in Paraíba and Pernambuco and shares characters with Excorallana antillensis (Hansen, 1890), in having the head and pereon unornamented; the pleon with tubercles; and the pleotelson triangular, with a lateral incision and with four tubercles on the anterior margin. However, the two species differ in the head size, length of the antenna, shape of the frontal lamina, and number and arrangement of tubercles on the pleon.

Identification and illustrations.The specimens were observed under a stereomicroscope fitted with a camera lucida, and the drawn specimens were stained with chlorazol black, dissected, and mounted in glyceringelatin slides.Digital illustrations were made according to Coleman (2003).The type material is deposited in the Crustacea collection of the Museu de Oceanografia Prof. Petrônio Alves Coelho da Universidade Federal de Pernambuco, Recife, Brazil (MOUFPE).
The terminology follows Delaney (1984) and Watling (1989).In "material examined", the term "sex undefined" is used when it was not possible to observe the male appendage on pleopod 2, due to poor preservation or because the individual was a manca.Diagnoses are given for previously described species.
In the geographic distribution, the new records are in bold.
Remarks.This species has marked sexual dimorphism.Important variations were found in the material examined.According to Lemos de Castro and Lima (1971), males have two tubercles on the head and two on the pereonite 1, while the female is devoid of tubercles.However, similarly to males, some females examined had two tubercles on the head and two on the pereonite 1, but less developed (females showing male characteristics: MOUFPE 876 -9 females, MOUFPE 871 -2 females, MOUFPE 976 -5 females).Furthermore, according to Lemos de Castro and Lima (1971), males have more tubercles on the pleon than the females, but the same female specimens cited above had tubercles, as in the males (Fig. 1).
Description (based on female, 22 mm, MOUFPE 870).Head 0.4x wider than long; small eyes.Antennular peduncle 3-articulated, article 1 not dilated; flagellum 10-articulated.Antenna reaching pereonite 4; peduncle 5-articulated; flagellum with 31 articles.Frontal lamina 1.6x longer than wide, narrower in the middle, apex rounded.Maxilla 1 forming large recurved spine; inner lobe simple, with slightly bulbous end.Maxilliped composed of seven articles, with third article of palp approximately 2.5x longer than wide.Mandible with elongated incisor process, slightly curved.Pereon dorsally smooth.Pereopod 1 with basis moderately inflated, 1.7x longer than wide; ischium smooth, approximately 2.2x longer than wide; merus almost as long as wide, posterodistal angle with one simple seta; carpus 2.6x wider than long, anterior margin with one small simple seta; propodus with anterior margin bearing two small simple setae, and one simple seta on anterodistal angle; dactylus robust, hook-shaped, about 2.5x longer than wide.Pereopod 2 with basis moderately inflated, 2.1x longer than wide; ischium 1.9x longer than wide, with one small, robust setae on anterodistal angle; merus 1.2x longer than wide, anterior margin with two groups of robust setae (2-2), posterodistal angle with two simple setae, anterodistal angle with one simple seta; carpus anterior margin with two small simple setae; propodus 2.1x longer than wide, anterior margin with one small simple seta, anterodistal angle with one simple seta; dactylus moderately curved, about 2.4x longer than wide.Pereopod 3 with basis smooth, 2.3x longer than wide; ischium smooth, about 2x longer than wide; merus 1.4x longer than wide, anterior margin with two simple setae, posterior margin with two long simple setae; carpus 0.5x wider than long, anterodistal angle with two small simple setae; propodus 2.1x longer than wide, smooth; dactylus 2.8x longer than wide, Excorallana from N and NE Brazil with a new species Nauplius, 25: e2017026 smooth, moderately curved.Pereopod 4 with basis ovate, 1.7x longer than wide; ischium 1.3x longer than wide, anterior margin with two groups of simple setae (2-2), anterodistal angle with two simple setae and posterodistal angle with two simple (one short and other long) setae; merus almost as long as wide, anterior margin with two simple setae, anterodistal angle with two simple (one short and other long) setae, posterodistal angle with four simple setae; carpus 1.7x longer than wide, anterior and posterior margin with one small simple seta, anterodistal angle with three (one robust and two simple) setae, posterodistal angle with one simple seta; propodus 4.5x longer than wide, one seta close to anterodistal angle; dactylus moderately curved, approximately 2.4x longer than wide.Pereopod 5 with basis moderately ovate, 1.6x longer than wide, smooth; ischium approximately 2.6x longer than wide, anterior margin with two groups of simple setae (1-2), anterodistal angle with three simple setae, posterodistal angle with five (three short and two long) simple setae; carpus with anterior margin bearing two simple setae; propodus 3x longer than wide, anterior margin with one simple seta, anterodistal angle with four simple seta, one long and three short; dactylus moderately curved, about 3.3x longer than wide, narrower than ischium.Pereopod 6 with basis ovate, 2x longer than wide, smooth; ischium about 1.7x longer than wide, anterior margin with two simple setae, anterodistal angle with two simple setae and posterodistal angle with four (two long and two short) simple setae; merus 1.4x longer than wide, one anterior simple seta, anterodistal angle with four (one short and three long) setae, posterodistal angle with eight (two short robust and six simple) setae; carpus 2.1x longer than wide, anterodistal angle with three (two short and one long) setae, posterodistal angle with six long simple setae; propodus 4x longer than wide, anterior margin with two small simple setae, anterodistal angle with one simple seta; dactylus moderately curved, 2.4x longer than wide, narrower than propodus.Pereopod 7 with basis ovate, 2.5x longer than wide, smooth; ischium about 1.5x longer than wide, anterior margin with one simple seta, anterodistal angle with two small simple setae and posterodistal angle with four (three long and one short) simple setae; merus 2.2x longer than wide, three anterior simple setae, anterodistal angle with one seta, posterodistal angle with three (one robust and two simple) setae; carpus 1.4x longer than wide, anterior margin with one robust seta, anterodistal angle with two (one short and one long) setae, posterodistal angle with five long simple setae; propodus 3.3x longer than wide, anterior margin with three groups of simple setae (1)(2), antero and posterodistal angles with two simple setae; dactylus moderately curved about 3.3x longer than wide, less wide than propodus.
Pleonite 1 not visible.Pleonite 2 with tubercles on posterior region.Pleonite 3 with tubercles on posterior margin and one median tubercle.Pleonite 4 with three short carinae on anterior margin; lateral tubercles on posterior margin and two median tubercles.Pereonite 5 with four short carinae on anterior margin; posterior margin with three tubercles on each side of median line and one median tubercle.Pleotelson triangular with rounded apex and lateral incision, four tubercles on anterior margin of pleotelson divided into two groups .Uropods slightly surpassing apex of pleotelson, margins covered with plumose setae.
Remarks.This species shares some characters with Excorallana antillensis (Hansen, 1890) from the Caribbean Sea, but they differ regarding (characters of E. antillensis in brackets): (i) the head is 0.4x as wide as long (0.7x as wide as long); (ii) the antenna reaches the pereonite 4 (pereonite 3); (iii) the frontal lamina is 1.6x longer than wide, narrowing in the middle and with a rounded apex (triangular with rounded edges); (iv) pleonite 4 three small carinae (without carinae); (v) pereonite 5 with four short carinae on the anterior margin (without carinae); (vi) endopod and exopod of the uropods acute (rounded); and (vii) pleotelson and uropod margins covered with plumose setae (simple setae).
Geographic distribution.Brazil: Paraíba and Pernambuco (Fig. 8).Diagnosis [modified from Hansen (1890)].Head without tubercles, with very large and continuous eyes, except for small anterior area.Frontal lamina approximately 3x longer than wide, narrower in the middle, apex rounded (Fig. 17).Antennular peduncle with article 1 not dilated.Antenna reaching pereonite 3. Pereonites 1-4 dorsally smooth, 5-7 with one line of tubercles on posterior margin.Pleon with longitudinal groove bearing tubercles.Pleonite 1 dorsally smooth.Pleonite 2 with transversal tubercles on posterior margin.Pleonites 3, 4 with double line of small tubercles.Pleotelson triangular, with lateral incision, anterior margin with six tubercles arranged in two groups  separated by one groove; lateral margins heavily coated with long setae, apex slightly rounded.Uropods margins heavily coated with setae, reaching apex of pleotelson.
Diagnosis [modified from Lemos de Castro (1960)].Head without tubercles, with medium sized eyes, not reaching anterior margin of head.Antennular peduncle with article 1 very dilated.Antenna reaching pereonite 2. Frontal lamina trapezoidal (Fig. 17).Pereonites 1-5 smooth dorsally, 6 and 7 with small tubercles (nearly imperceptible) laterally on posterior margin.Pleonite 1 dorsally smooth.Pleonite 2 with small tubercles on posterior margin.Pleon with longitudinal groove in the middle, extending from pleonites 3-5, with longitudinal line of tubercles.Pleonites 3-5 with double transversal line of tubercles.Pleotelson triangular, acute apex, with lateral incision on each side; anterior margin with four tubercles, arranged in two groups ; lateral margins heavily coated with setae; midline with soft groove; two small tubercles prior to lateral incisions.Uropods slightly surpassing tip of pleotelson, margins heavily coated with long setae.
Remarks.According to Lemos de Castro (1960), the uropods have the same length as the pleotelson, while in our material, they exceed the pleotelson.Also, the two rows of posterior tubercles on pereonites 6 and 7 found in E. richardsoni were not found, but instead one row of very small tubercles, and the median area was smooth dorsally.Lemos de Castro (1960) also noted that E. richardsoni has two rows of tubercles on pleonites 2-5, while the specimens examined herein have only two rows of tubercles on the posterior margin of the segment.Finally, Lemos de Castro (1960) reported that the males identified as Corallana acuticauda Miers, 1881 (now assigned to genus Excorallana) from Alagoas, Brazil, by Richardson (1900) was actually a misidentification, and the specimens belong to E. richardsoni.Pires-Vanin (1998) agreed with Lemos de Castro's observation, and therefore the geographical distribution of E. acuticauda should be restricted to the type locality (Hotspur Bank off southern Bahia, Brazil).
Remarks.The two specimens examined in this study showed some differences from the original description of Hansen (1890) and that by Lemos de Castro and Lima (1971) concerning the number of tubercles on pleonite 5 and on the anterior margin of the pleotelson.Hansen (1890) described this species as having the pleon smooth and only two tubercles on the anterior margin of the pleotelson.According to Richardson (1905), Hansen's material was a juvenile specimen, probably a female in the process of ecdysis (Kensley and Schotte, 1989).Lemos de Castro and Lima (1971) illustrated tubercles only on pleonite 5 and two tubercles on the anterior margin of the pleotelson.However, in the material examined, adult females measuring 5 mm and 6 mm, have tubercles on pleonites 1-5, very short tubercles on pleonites 1-4, and four tubercles on the anterior margin of the pleotelson.We consider these differences to be morphological variations between age and localities, so they do not differ sufficiently to warrant the establishment of a new species.Additional specimens from the vicinity of the type locality are needed for a species redescription.
Depth range.Unknown.
Remarks.Lemos de Castro and Lima (1971) redescribed this species based on material collected in Amapá (02°57'N 49°04'W).In this description, they stated that the pleotelson has a lateral incision; however in their figures 35 and 36 the lack of any incision mentioned in their description is clear (p.153).Additionally, the lateral incision is absent in the original description of Hansen (1890), as well as in the material studied herein.

Figure 2 .
Figure 2. Distribution of Excorallana bicornis Lemos de Castro and Lima, 1971 for Brazilian waters.