Pseudione minimocrenulata Nierstrasz & Brender

Kazmi, Quiddusi B. & Boyko, Christopher B., 2005, A new locality and host for Pseudione minimocrenulata Nierstrasz & Brender à Brandis, 1931 (Crustacea: Isopoda: Bopyridae) in the Indian Ocean, with comments on the identity of the type specimens, Zootaxa 925, pp. 1-10 : 2-8

publication ID	https://doi.org/ 10.5281/zenodo.171098
DOI	https://doi.org/10.5281/zenodo.6265579
persistent identifier	https://treatment.plazi.org/id/2F148794-FF90-EA7D-C836-FA0CDF8E0AC9
treatment provided by	Plazi
scientific name	Pseudione minimocrenulata Nierstrasz & Brender
status

Treatment

Pseudione minimocrenulata Nierstrasz & Brender View in CoL à Brandis, 1931 ( Figures 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Pseudione minimo crenulata View in CoL Nierstrasz & Brender à Brandis, 1931: 160–163 (part: Kei Islands material only), figs. 22–28; Bourdon, 1968: 187, 188 (mention); Bourdon, 1972b: 825 (place in genus).

Pseudione minimocrenulata View in CoL .— Shiino, 1952: 41 (list); Bourdon, 1976: 366 –369, figs. 9, 10; Kensley, 2001: 226 (list).

“bopyrid species”.— Tirmizi & Javed, 1993: 115.

Not Pseudione minimo crenulata Nierstrasz & Brender à Brandis, 1931: 160–163 (St. Croix material only = P. confusa maxillipedis Bourdon, 1972 ).

Not Pseudione minimocrenulata View in CoL .— Markham, 1988: 56 (= P. confusa maxillipedis Bourdon, 1972 ).

Material Examined. 1 mature female (16.3 mm), 1 mature male (4.8 mm), from right branchial chamber of Agononida incerta (host lacking, its sex and CL unknown), coll. Danish Expedition to the Kei Islands, st. 51, 05°46'S, 132°51'E, 348 m, 7 Sept. 1922 ( ZMUC CRU 7270).— 1 mature female (12.0 mm), 1 mature male (4.0 mm), from left branchial cavity of male Munida andamanica (21.0 mm CL); 1 mature female (11.5 mm) and cryptoniscid larva, 1 mature male (3.5 mm) from right branchial cavity of male M. andamanica (27.0 mm CL); 1 mature female (8.0 mm), 1 mature male (3.5 mm), 1 mature female (9.5 mm), 1 mature male (4.0 m) from right and left, respectively, branchial cavities of male M. andamanica (13.0 mm CL exclusive of rostrum, broken after photography), all coll. International Indian Ocean Expedition ( IIOE), R.V. Anton Bruun, cruise 8, st. 397C, 26°07'S, 34°01'E, (off Mozambique), 600–665 m, 29 Sept. 1964.

Redescription (based primarily on dextral female and male from 27.0 mm CL host and sinistral female and male from 21.0 mm CL host).

Female ( Fig. 2 View FIGURE 2 A, B) body length 11.5 mm, maximum width 6.0 mm. Pereon with slight dextral curve ( Fig. 2 View FIGURE 2 A). All body regions and pereomeres distinctly separated.

Head broader than long, strongly produced with large anterior lamina equal to approximately onefifth length of head, margins of lamina crenulated ( Fig. 2 View FIGURE 2 A). Eyes absent. Barbula as two long lateral lobes, both crenulated at edges and scaled on surfaces, median lobe weakly produced ( Fig. 4 View FIGURE 4 B–D). Antennule of three articles, antennae of five articles, both distally setose ( Fig. 3 View FIGURE 3 A–D). Maxilliped ( Fig. 4 View FIGURE 4 B, C) with thin distally acute spur; palp short, distally tapering and rounded, nonarticulating (damaged, not shown). Pereon of seven pereomeres, broadest across pereomere III, gradually tapering anteriorly and posteriorly; pereomere I with slightly convex posterior margin, II with sinuous posterior margin, III–VII with strongly concave posterior margins; approximately threefourths of pereomere I medially obscured by head. First oostegite covered in minute scales, proximal lobe ovate (dorsal margin folded in specimen illustrated), distal lobe subtriangular, distally tapering and rounded, internal ridge with numerous short, digitate lobes along length ( Fig. 4 View FIGURE 4 A). Coxal plates as small irregular lobes on pereomeres I–IV, clearly separated from pereomeres, and with crenulate lateral margins. Dorsolateral bosses clearly demarcated on pereomeres I–IV with right side larger than left. Pereomeres II–IV with distinctly demarcated tergal area, not projecting. Oostegites entirely enclosing marsupium ( Fig. 2 View FIGURE 2 B). Pereopods approximately subequal but with slight increase in size posteriorly ( Fig. 3 View FIGURE 3 E, F). Dorsal margin of propodus and ventral margin of carpus and merus with thin band of scales; propodus stout, dactylus short and blunt. Bases of pereopods with scalecovered bosses on distodorsal margin. First pair of pereopods adjacent to but not surrounding head region; all pereopods evenly spaced.

Pleon with five distinct pleomeres plus pleotelson; posterior margins of all pleomeres strongly concave ( Fig. 2 View FIGURE 2 A). Pleomeres I–IV with biramous pleopods and uniramous lateral plates ( Fig. 2 View FIGURE 2 A, B). All pleopods with subequal lamellar exopodites and endopodites, broad proximally and distally tapering, pleopods slightly decreasing in size posteriorly, all having surfaces with scattered small papillae; lateral plates tuberculate, strongly produced and crenulate on lateral margins, those on longer side better developed and more crenulate than those on other side, all directed posterolaterally and with few papillae scattered on surface, margins crenulate but not as strongly as on pereomeres. Uropods uniramous, of nearly same shape and size as exopodite of pleopod V, surfaces with scattered papillae.

Male ( Fig. 2 View FIGURE 2 C, D) length 4.0 mm, maximal width 2.5 mm.

Head oblong, distinct from first pereomere ( Fig. 2 View FIGURE 2 A). Eyes absent. Antennule of three articles, distally setose; antenna of five articles, distally setose, extending beyond margin of head ( Fig. 5 View FIGURE 5 A–D).

Pereomere IV broadest, body tapering anteriorly and posteriorly. Pereomeres directed laterally, distolateral margins of all pereomeres tapering into rounded tips, midventral tubercles present on all segments. No detectable pigmentation. Pereopods ( Fig. 5 View FIGURE 5 E, F) all subequal, carpus and merus fused, all other articles separated, dactylus long and acute, palm of propodus with row of low blunt stout setae and surrounding region of granular scales, distoventral margin of carpus with granular scales and few distal setae.

Pleon of six separate pleomeres. Pleomeres all directed laterally, distolateral margins of all pleomeres tapering and rounded. Pleomere VI (pleotelson) subtriangular with rounded posterolateral lobes ( Fig. 2 View FIGURE 2 C, D). Pleopods as low, elongate, rounded lobes on pleomeres I–V ( Fig. 2 View FIGURE 2 D). No midventral tubercles or uropods.

Comparison with Previously Reported Specimens. The IIOE material is essentially identical with the specimens reported by Nierstrasz & Brender à Brandis (1931) from the Kei Islands and Bourdon (1976) from Madagascar. The males are slightly more similar to the Indonesian specimens but appear to fall well within the range of bopyrid intraspecific variability.

Discussion. The type material of Pseudione minimocrenulata consists of two pairs of specimens, one pair collected in the Kei Islands and one pair from St. Croix: a dextral mature female (8.3 mm) and mature male (2.6 mm) from the right branchial chamber of a female Munida stimpsoni A. MilneEdwards, 1880 (19.1 mm CL; identified by M. de Saint Laurent, Frederikssted, St. Croix, U.S. Virgin Islands, 7, Feb. 1906, coll. Dr. T. H. Mortensen; ZMUC CRU4856). However, the description and illustrations of Nierstrasz & Brender à Brandis (1931) are almost exclusively of the Kei Islands specimens with the St. Croix pair being only mentioned in passing. Bourdon (1976), in the only substantive treatment of this species since the original description, examined and discussed only the Kei Islands specimens. It is clear from an examination of the two syntypic pairs that these represent two separate Pseudione taxa with the St. Croix specimens belonging to the subspecies currently known as P. confusa maxillipedis Bourdon, 1972 b, which was originally described from Cuban material. In both the St. Croix female and the female syntypes of P. confusa maxillipedis the maxilliped has a large, unarticulated palp with long distal setae (the palp being short and tipped with short setae in P. minimocrenulata ) and the host is the same species for both the Cuban and St. Croix specimens. In order to fix the identity of P. minimocrenulata and to continue accepted usage of its name, we select the female specimen from the Kei Islands as the lectotype. The Kei Islands male and both of the St. Croix specimens therefore become paralectotypes of P. minimocrenulata , while the two St. Croix specimens are also synonymous with P. confusa maxillipedis .

The genus Pseudione has been regarded as the most primitive of the Bopyridae ( Shiino 1965) , although this statement cannot apply to all currently included species as the genus is likely paraphyletic ( Adkison 1988; Boyko 2004a). The association of bopyrids and galatheids is very old, with evidence of host branchial chamber swellings found as far back as the Jurassic ( Markham 1986) and galatheids may have been the original hosts for bopyrids among the Decapoda . It is worth noting that swellings on decapod carapaces can result from influences other than bopyrids (Boyko, personal observation), so it is unclear whether all fossilized swellings are caused by bopyrids because no actual fossilized bopyrids have been found, and the generic identities of fossil bopyrids remain unknown.

The IIOE material contained eleven species of Munida , but only three of these were found bearing bopyrids: M. andamanica , M. arabica Tirmizi & Javed, 1992 , and M. heteracantha Ortmann, 1892 . Munida andamanica is also infested by Aporobopyrina javaensis Bourdon, 1972 a, from Java, Pseudione andamanicae Bourdon, 1976 , from Madagascar, and Aporobopyrus retrorsa ( Richardson, 1910) from the Philippines ( Boyko, 2004b). Interestingly, the other eight species of Munida collected by IIOE have almost the same longitudinal range as the three infested species ( Tirmizi & Javed 1993) but were not found to harbour any bopyrid parasites, although A. incerta is known to be parasitized by P. minimocrenulata in Madagascar ( Bourdon 1976). Whether this represents a degree of host specificity by the bopyrids is unknown because data are still very limited. The ranges of the two known hosts for Pseudione minimocrenulata greatly overlap as both Munida andamanica and A. incerta are found from the east coast of Africa into the Arabian Sea and across to the Maldives, Java Sea, Moluccas, Philippines and Japan ( Tirmizi & Javed 1993). The apparently restricted distributions of bopyrid parasites relative to those of their hosts reflect the principle of Pielou (1974) that parasites do not range as far as their hosts, but it would be presumptive to make any conclusions based on the limited data available for galatheidinfesting bopyrids.