Sphaeroma Bosc, 1802

Khalaji-Pirbalouty, Valiallah & Wägele, Johann-Wolfgang, 2010, A new species and a new record of Sphaeroma Bosc, 1802 (Sphaeromatidae: Isopoda: Crustacea) from intertidal marine habitats of the Persian Gulf, Zootaxa 2631, pp. 1-18 : 2

Genus Sphaeroma Bosc, 1802

Diagnosis. Maxilliped robust, particularly the palp; internal border of endite with fringe of robust, circumplumose setae with swollen base; apical margin of endite with smooth setae and often some plumose seta set in amongst fine simple setae; palp articles 2–4 often lacking mesial lobes, inferior margins straight, bearing dense fringes of long, bare or finely plumose setae; palp article 5 longer than 4. Antennule peduncle article 3 elongate, slender and often more than 2 times as long as article 2. Pereopods 1–3 ischium and merus superior margins bearing dense fringes of long stiff finely plumose setae. Pereopods 4–5 are shorter than the other pereopods with the basis bearing inferiorly extended lobes; merus, carpus and propodus are short. Pereopods 6–7 basis, ischium, merus inferior and superior margins bearing dense fringes of long fine setae. Penes flat, separated, with folded margins, often covered with several small fine setae.

Remarks. The genus Sphaeroma is closely related to Lekanesphera Verhoeff, 1943. In addition to some characters mention by Jacobs (1987), Lekanesphera is distinct from Sphaeroma in having a maxilliped with palp article 5 sub-equal or shorter than palp article 4 (in Sphaeroma article 5 longer than article 4); antennule peduncle article 3 less than two time as long as article 2. Moreover, the setation on pereopods 1–3 and 6–7 of Lekanesphera is not as dense as in Sphaeroma .

The genus Sphaeroma Bosc, 1802 includes 41 species, which currently are considered as valid ( Appeltans et al. 2010). However, based on the published descriptions and drawings, some of them should be assign to other genera.

Sphaeroma intermedium Baker, 1926 was first described as Exosphaeroma intermedia Baker, 1926 and later transferred to Sphaeroma genus by Harrison & Holdich, 1984. Based on description and drawing of Baker, 1926 and also Harrison & Holdich, 1984, this species with having the following characters is transferred to Lekanesphera: Maxilliped palp articles with more or less pronounced lobes, endite semicircular distal margin bearing stout circumplumose setae, palp article 5 seb-equal to article 4; pereopods 4–5 not robust and without long setae on ischium and merus superior margins, merus and carpus not short; pereopods 6–7 basis, ischium, merus superior margins without dense fringes of long fine setae.

Sphaeroma dumerilii Leach, 1818 and Sphaeroma savignii H. Milne Edwards, 1840 , synonymised with Dynamenopsis dumerilii by Monod 1933 and then accepted as Dynamenella dumerilii .

Based on the pleotelson with subapical foramen and uropod without acute teeth, Sphaeroma globicauda Dana, 1853 would not appear to be a species of Sphaeroma (it is probably belongs to Dynamenella or Paradella ).

Sphaeroma granti Walker & Scott, 1903 with well extended pleotelson apex and lateral marked notch of pleotelson does not appear to belong in Sphaeroma .

Finally, based on the shape of the maxilliped with the lobate palp articles, a maxillule with four circumplumose robust setae on mesial lobe, pereopod 4 with a long carpus, pereopods 6 and 7 lacking dense, long marginal setae on the ischium, merus and carpus, Sphaeroma mukaii Nunomura, 2006 does not belong in Sphaeroma (but the correct generic placement is unknown).