Excorallana subtilis ( Hansen, 1890 )

Souza-Filho, Elinai dos Santos Silva Jesser F., 2017, Species of Excorallana (Isopoda, Corallanidae) from northern and northeastern Brazil, with description of a new species, Excorallana lemoscastroi sp. nov., Nauplius (e 2017026) 25, pp. 1-21 : 15-17

Excorallana subtilis ( Hansen, 1890)

( Figs. 13 , 14)

Corallana subtilis Hansen, 1890: 382 , figs. 3–30. Richardson, 1901: 519.

Excorallana subtilis . – Richardson, 1905: 146, fig. 130. – Carvacho and Yañez, 1971: 130. – Delaney, 1984: 6. – Kensley and Schotte, 1989: 160. – Delaney, 1989: 3,5. – Pires-Vanin, 1998: 612. – Barriga and Briones, 1992: 370.

Excorallana sublitilis . – Lemos de Castro and Lima, 1971: 138, figs. 15–25 (misspelling).

Material examined. 2 adult females (1 drawn) ( MOUFPE 13.012 ), NE IV III 4 ªp. REVIZEE BENTOS, Amapá, 01º37’59”S 38º09’12”W .

Diagnosis [modified from Hansen (1890)]. Head without tubercles, with medium sized eyes. Frontal lamina wider than long, sub-trapezoidal ( Fig. 17 ). Antennular peduncle with article 1 very dilated. Antenna reaching pereonite 3. Pereon smooth dorsally. Pleon with pleonite 1 not visible. Pleonites 2–5 with tubercles on posterior margin, but pereonite 3 smooth in the middle and pereonite 4 with only one median small tubercle. Pleonite 5 with one short median tubercle and three lateral tubercles. Pleotelson triangular, anterior margin with two tubercles, acute apex and lateral incision. Uropods slightly surpassing apex of pleotelson, margins coated with setae.

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 pleonite5 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.

Geographic distribution. USA: Florida; Caribbean Sea: Saint Thomas; Brazil: Amapá, Rio de Janeiro ( Lemos de Castro, 1971; Kensley and Schotte, 1989; Pires-Vanin, 1998; this study) ( Fig. 14).

Figures

Figure 13. Excorallana subtilis (Hansen, 1890), female, 6 mm.(MOUFPE 13.012), habitus. Detail showing smooth area, without tubercles, prior to lateral incision. Scale= 1 mm.

Figure 17. Morphological variation of the frontal lamina among the Brazilian species of the genus Excorallana.