Rhopalione uromyzon Pérez, 1920

Boyko, Christopher B. & Williams, Jason D., 2024, New records of bopyrid parasites (Crustacea, Isopoda, Epicaridea) of pea crabs (Crustacea, Decapoda, Pinnotheridae) with descriptions of two new species of Rhopalione Pérez, 1921 and a review of the genus, Zoosystema 46 (7), pp. 149-175 : 159-162

Rhopalione uromyzon Pérez, 1920

( Figs 4 ; 5 )

Rhopalione uromyzon Pérez, 1920a: 1615-1617 , figs 1-3 [ ex Ostracoteres spondyli Nobili, 1905 (now Discorsotheres spondyli (Nobili, 1905)) , Persian Gulf]. — Pérez 1920b: 102-103, fig. 45 [information from Pérez 1920a]. — Nierstrasz & Brender à Brandis 1923: 69 [mention]. — Shiino 1952: 34 [mention]. — Bourdon et al. 1981: 500-501 [mention]. — Page 1985: 199-201 [mention]. — Markham 1990: 562 [mention]. — Kensley 2001: 226 [list]. — An et al. 2014: 1, 2, table 1 [mention; list], 4 [key to species]. — Ahyong 2018: 561 [mention]. — Ahyong & Boyko 2019: 283-284, 286 [mention], 287 [key to species]. — Williams et al. 2023: 533 [list].

not Rhopalione uromyzon – Nierstrasz & Brender à Brandis 1931: 175-176 [host unknown, Zamboanga, Philippines; specimen examined herein] (identified as Rhopalione sinensis Markham, 1990 ).

TYPE MATERIAL EXAMINED. — United Arab Emirates • 1 syntype ♀ (8.1 mm TL), ex female Discorsotheres spondyli Nobili, 1905 (6.8 mm CW), St. LIII, “banc au N.E. de l’île Arzana et pêche côtière dans les polypiers” [Îsle Arzana or Arzanah Island , 24°48’N, 52°34’E]; 1901; Mission Bonnier-Pérez Côtes d’Arabie leg.; MNHN-IU-2024-3187 (= Ep 910) • 1 syntype ♀ (6.30 mm TL), 1 syntype ♂ (3.00 mm TL), ex female D. spondyli (damaged, unmeasurable), St. LIII, “banc au N.E. de l’île Arzana et pêche côtière dans les polypiers”; 1901; Mission Bonnier-Pérez Côtes d’Arabie leg.; MNHN-IU-2024-3188 (= Ep 911) • 2 syntype ♀ (4.35, 5.55 mm TL), 2 syntype ♂ (3.45, 3.68 mm TL), ex ♀ D. spondyli (5.6 mm CW), St. LIV, “dragages à 5 brasses, 8 milles au N. N. O. d’Arzana”; 1901; Mission Bonnier-Pérez Côtes d’Arabie leg.; MNHN-IU-2024-3189 (= Ep912) • 1 syntype ♀ (3.15 mm TL), 1 syntype ♂ (1.50 mm TL), ex female D. spondyli (4.5 mm CW), St. LIV, “dragages à 5 brasses, 8 milles au N. N. O. d’Arzana ”; 1901; Mission Bonnier-Pérez Côtes d’Arabie leg.; MNHN-IU-2024-3190 (= Ep913). No data [ United Arab Emirates] • 1 syntype ♀ (3.15 mm TL), 1 syntype ♂ (3.08 mm TL), host not present; MNHN-IU-2024-3191 (= Ep914) • 1 syntype ♀ (6.15 mm TL), 2 syntypes ♂ (2.1, 4.8 mm TL), host not present; MNHN-IU-2024-3192 (= Ep915)• 1 syntype ♀ (4.35 mm TL), ex female D. spondyli (damaged, unmeasurable); MNHN-IU-2024-3195 (= Ep919) • 1 syntype ♀ (3.90 mm TL), 1 syntype ♂ (2.85 mm TL), host not present; MNHN-IU-2024-3193 (= Ep917) • 1 syntype ♀ (4.65 mm TL), 2 syntypes ♂ (1.01, 3.08 mm TL), ex 1 of 2 females D. spondyli (damaged, unmeasurable); MNHN-IU-2024-3194 (= Ep918) • 1 syntype ♂ (3.41 mm TL), ex 1 of 2 females D. spondyli (damaged, unmeasurable); MNHNIU- 2024-3199 (= Ep 916) • 1 syntype ♀ (3.90 mm TL), ex female D. spondyli (damaged, unmeasurable); MNHN-IU-2024-3196 (= Ep920) • 1 syntype ♀ (3.08 mm TL), ex female D. spondyli (5.20 mm); MNHN-IU-2024-3197 (= Ep921).

NON-TYPE MATERIAL EXAMINED. — No data [ United Arab Emirates] • 1 cryptoniscid larva (0.45 mm TL), host not present; MNHNIU- 2024-3198 (= Ep922).

REDESCRIPTION

Female ( Fig. 4 ), based on MNHN-IU-2024-3187

Body length 8.10 mm, maximal width 6.74 mm, head length 1.60 mm, head width 1.98 mm. Pereon essentially straight, left and right side subequal ( Fig. 4A, B ). All body regions and pereomeres distinctly segmented. Head broader than long, strongly produced with frontal lamina equal to approximately one-fifth length of head ( Fig. 4A ), small portion of pereomere 1 median obscured by cephalon; barbula ( Fig. 4D ) with two thin, distally tapering projections, entirely covered in minute papillae. Eyes absent. Antennule ( Fig. 4C ) of three articles, antenna ( Fig.4C ) of four articles. Maxilliped ( Fig. 4G ) with thin distally acute spur; palp absent, distolateral margin subquadrate, produced and with short setae on edge. First oostegite proximal lobe ovate, distal lobe subtriangular with median acute projection ( Fig. 4E, F ), internal ridge with several thin, distally rounded projections ( Fig. 4E ). Pereon composed of seven pereomeres, broadest across pereomere 5, gradually tapering anteriorly and posteriorly; pereomeres 1 and 2 with convex posterior margins, 4 nearly straight, 5-7 with concave posterior margins ( Fig. 4A ). Coxal plates as large, irregular lobes on pereomeres 1-5, clearly separated from pereomeres. Dorsolateral bosses on pereopods 1-6 large, oblong, and clearly demarcated with left and right sides subequal. Pereomeres 1-6 with clearly demarcated elongate median region having raised and rounded aspect; no tergal projections. Oostegites enclosing marsupium ( Fig. 4B ). Pereopods all subequal ( Fig. 4 H-J) with indistinct separation of propodus, carpus and merus in anterior pairs; edge of propodus meeting tip of dactylus with area of low serrate scales, and distally acute, proximally subquadrate teeth ( Fig. 4J ); distoventral tip of carpus with tuft of thick setae; ventral margin of carpus and distal portion of merus with thin, short setae. First pair of pereopods surrounding head region, others evenly spaced. Pleon with five distinct pleomeres plus pleotelson; posterior margins of pleomeres 1 and 2 sinuous, those of 3-5 becoming progressively concave ( Fig. 4A ). Pleomeres 1-5 with biramous pleopods and uniramous lateral plates ( Fig. 4B ); endopodites and exopodites of all pleopods rounded and subequal in size; lateral plates strongly produced and distally rounded; edges and surfaces of all lateral plates smooth; uropods typically uniramous (see under Variation below), subequal in shape and size to pleopods and lateral plates.

Male ( Fig. 5 A-G), based on MNHN-IU-2024-3189 Length 3.45 mm, maximal width 1.56 mm, head length 0.28 mm, head width 1.04 mm, pleon length 0.72 mm. Head subovate, widest posteriorly, distinct from first segment of pereon ( Fig. 5A, D ). Eyes usually present, small ( Fig. 5A ). Antennule ( Fig. 5E ) of three articles, distally setose, antenna ( Fig. 5E ) of four articles, distally setose, not extending beyond margin of cephalon. Pereomere 3 broadest, others tapering anteriorly and posteriorly. All pereomeres directed laterally, distolateral margins of rounded, dorsal margin produced into a gently rounded arch ( Fig. 5B ). No detectable pigmentation. Pereopods ( Fig. 5F, G ) subequal, all articles distinctly separated, palm of propodus with row of low blunt teeth, distoventral tip of carpus with distal tuft of setae. Pleon with five segments plus pleotelson. Pleomere 1 directed laterally, 2-5 directed progressively posterolaterally, distolateral margins of all pleomeres rounded; pleomeres 1 and 2 strongly produced medially into rounded arch as for pereomeres, 3-5 dorsoventrally flattened; pleotelson subtriangular with short posterolateral lobes separated by shallow medial indentation; anal cone not observed, distal tips of posterolateral lobes without setae; midventral tubercles absent; pleopods present as very low rounded swellings; uropods absent.

Variation

Head shape of female is variable from nearly rounded ( Fig.5H ) to oblong ( Fig. 5I, J ), but always broader than long; occasionally the barbula has a reduced medial projection. The antenna usually has four but may have five articles, the distalmost article very small and slender. The anteroposterior compression of the pereomeres is variable, with pereomeres broadly separated in some specimens while in others they have thin median portions. The pleomeres are occasionally indistinctly separated. Lateral plate development ranges from oblong to distinctly elongate. Uropods are uniramous or biramous, but always resemble the pleopods. One specimen lacks both pleomere 5 and the uropods, and one has a lateral plate of pleomere 6 and biramous uropods only on the left side, but this is a developmental defect. Eyes of males can be present ( Fig. 5A ) or absent ( Fig. 5D ). The pleotelson of the male may lack the median indentation.

REMARKS

Pérez (1920a) gave only “du golfe Persique” as the locality data for R. uromyzon , but several lots contain original data labels, and complete station data for the Mission Bonnier-Pérez was listed by Nobili (1906). Pérez (1920a) listed “plus de 130 exemplaires” of the host Ostracotheres spondyli [now Discorsotheres spondyli (Nobili, 1905) ] that were collected by Mission Bonnier-Pérez, but Nobili (1906) only cited 124 specimens from stations LIII and LIV. This suggests that the parasitized crabs (at least 14 specimens based on the material examined) were not given to Nobili for study, and therefore should not be included in the type series of O. spondyli . Most of the jars of R. uromyzon contain a small handwritten label “vient de chez Mr. Le Prof. Pérez Novembre 1945,” suggesting that all were in the possession of Pérez when he died. Many of the vials now lack original data labels but are clearly part of the type series. All the hosts are female, as were apparently all the pinnotherid hosts collected by the Mission Bonnier-Pérez ( Pérez 1920a). One lot (MNHN-IU-2024-3194) contains the name “ Hypurione ” handwritten on a small label; this is evidently a manuscript name for the genus Pérez eventually named Rhopalione . The cryptoniscid larva (MNHN-IU-2024-3198) is only questionably referred to this species as the details of its collection are unknown and Pérez himself questioned its identity on the specimen label; it is not considered part of the type series. An additional female D. spondyli (7.30 mm) was found in the same jar with the type vials of R. uromyzon , but given that it was ovigerous, it probably never possessed any parasites and may have been used as comparative material.

Figures

FIG. 4. — Rhopalione uromyzon Pérez, 1920, syntype female (MNHN-IU-2024-3187) (8.1 mm): A, dorsal view; B, ventral view; C, right antennule and antenna; D, barbula; E, left oostegite 1, inner view; F, left oostegite 1, outer view; G, left maxilliped, outer view; H, left pereopod 1; I, left pereopod 7; J, close-up view of dactylus, propodus and carpus ending of pereopod 7. Scale bars: A, B, 1 mm; C, G, I, 100 µm; D, 200 µm; E, F, 500 µm; H, 250 µm; J, 50 µm.

FIG. 5. — Rhopalione uromyzon Pérez,1920:two syntype males (MNHN-IU-2024-3189)(A-C, E-G: 3.45 mm,D:3.68 mm),one syntype female (MNHN-IU-2024-3196) (H, 3.90 mm), 2 syntype females (I, 4.35 mm, J, 5.55 mm): A, dorsal view; B, lateral view; C, ventral view; D, dorsal view, E, left antennule and antenna; F, left pereopod 1; G, left pereopod 7; H-J, dorsal views. Scale bars: A-D, H, 500 µm; E-G, 100 µm; I, J, 1 mm.