Expanathura marcoi, Annisaqois & Wägele, 2021

Annisaqois, Manikmayang & Wägele, J. Wolfgang, 2021, Morphology and Taxonomy of Isopoda Anthuroidea (Crustacea) from Sulawesi with description of six new species, European Journal of Taxonomy 768, pp. 1-52 : 35-39

Expanathura marcoi sp. nov.

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Figs 24–26

Differential diagnosis

Expanathura with small eyes, remarkably large plumose setae on both antennae, subchelate pereopds 1–3; pereopod 1 propodus palm nearly straight, not crenulated and proximally without protrusion; pereopod 2 propodus palm proximally with 1 small protrusion, distal half of edge irregularly crenulated; merus and carpus posterior margin emarginated, pereopod 3 propodus palm proximally with 2 protrusions, exopod of uropod rounded, not lanceolate, margin distal half with concavity, with acute point in center before concave region.

Expanathura of the collaris group, differing from other species at first sight in the shape of the pereopod 1 propodus palm that has no proximal protrusion and crenulation. This is unique among this species group. Furthermore, the species has remarkably large plumose setae of the antennae. The protruding edge of peduncle article 2 of antenna 2 has been illustrated also for E. ardea , E. collaris sensu Müller (1993) and E. macronesia . Unfortunately, for several species of Expanathura the antenna has not been described with sufficient detail to allow a statement on the variation of this character.

Etymology

The species is dedicated to Marco Segre, owner of the Coral Eye Resort and promoter of coral reef biodiversity research, for enabling Indonesian students to work in his laboratory.

Material examined

Holotype INDONESIA • ♀ (3.1 mm); Bangka Island , off Coral Eye Resort; 1°44′20.22″ N, 125°8′46.07″ E; 1–2 m depth; in coral rubble; M. Annisaqois and J.W. Wägele leg.; Sep. 2019; MZB Iso 108.

Description of holotype

BODY. Shape as in previous species.

ANTENNAE. Antenna 1 first article of peduncle 1.4 times as long as wide, with three flagellum articles, on last article one aesthetasc. Antenna 2 peduncle second article distally with distinct protrusion; with 3 short flagellar articles. Remarkably large plumose setae on both antennae.

MANDIBLE PALP. With 3 articles, last article bearing 4 short setae. Mandibular endite without molar process, serrated lamina dentata, pars incisiva with two notches. Maxilla 1 distally with 1 big and 3 small spine-like teeth. Maxilliped with 5 articles, last article tiny, stout endite reaching half of palp article 3, distally two short setae; laterally on third palp article a thick, laterally finely serrated seta. Pereopods 1–3 subchelate.

PEREOPODS. Pereopod 1 propodus palm nearly straight, not crenulated and proximally without protrusion; pereopod 2 propodus palm proximally with 1 small protrusion, distal half of edge irregularly crenulated; merus and carpus posterior margin emarginated. Pereopod 3 propodus palm proximally with 2 protrusions on lower half, merus and carpus posterior margin emarginated. Pereopods 4–7 subsimilar, two sensory spines on propodus palm of P4–6, only 1 on P7.

PLEOPODS. Pleopod 1 exopod broad oval, with 17 feathered setae, endopod shorter and much narrower than exopod, distally as wide as proximally, with 5 feathered setae on distal margin. Exopod of uropod margin distal half with concavity, with acute point in center before concave region.

TELSON. Broad, tongue-shaped, with rounded apex, at broadest part with a pair of short lateral setae, 5 pairs of setae on distal margin.

Remarks

A remarkable detail of E. marcoi sp. nov. is the tooth-like protrusion on the second article of antenna 2. Such a protrusion has only been described before from E. collaris . The latter species has on the pereopod 1 propodus palm a large basal tooth and more distally another tooth and small crenulations, while in E. marcoi sp. nov. the propdus palm is straight, a unique feature in this genus.

Figures

Fig. 24. Expanathura marcoi sp. nov., holotype, ♀ (3.1 mm) (MZB Iso 108). Abbreviations: A1 = antenna 1; A2 = antenna 2; Md = mandible; Mx = maxilla; Mxp = maxilliped.

Fig. 25. Expanathura marcoi sp. nov., ♀, holotype (MZB Iso 108). Abbreviations: P1–P7 = pereopods 1–7.

Fig. 26. Expanathura marcoi sp. nov., ♀, holotype (MZB Iso 108). Abbreviations: Plp1–Plp4 = pleopods 1–4; UEx = exopod of uropod; UEn = endopod of uropod; Tel = telson.