Unionicola (Mutelicola) planicurvata, Gledhill & Vidrine, 2002

Gledhill, Terence & Vidrine, Malcolm F., 2002, Two new sympatric water-mites (Acari: Hydrachnidia: Unionicolidae) from the mutelid bivalve Aspatharia sinuata (von Martens) in Nigeria with some data on unionicoline-bivalve relationships, Journal of Natural History 36 (11), pp. 1351-1381 : 1361-1367

Unionicola (Mutelicola) planicurvata new species

(gures 6–10)

Description of male (gures 6a–k, 7a–h, 8a, b). With the characters of the genus and subgenus. Body elongate, tapering posteriorly, without a cauda; length excluding gnathosoma 780 (780–854, 817, n 52), width 440 (n 51). Dorsum (gure 6a) with a single dorsal shield, length 540 (540–588, 564, n 52), width 372 (n 51). Ventrally with epimera in four groups occupying slightly more than half ventral surface, ca the same size as dorsal shield. Anterior groups with prominent posterior apodemes extending beneath anterior margins of Ep.3 before becoming more laterally directed. Posterior groups with a well-de ned lateral cleft between Ep.3 and 4 and with wellrounded posterior margins to Ep.4; Ep.4 with pointed lateral extensions at point of IV-Leg insertions (gure 6b). Total epimeral length 488 (488–540, 514, n 52); median length Ep.31 4, 324 (n 51); median length Ep.4, 240 (n 51); epimeral width at Ep.3, 396 (n 51); epimeral width at Ep.4, 426 (n 51). Infracapitulum small, length 156 (144–156, 148, n 53); chelicerae short and stout, length, (162, n 51), cheliceral claw length (dorsal, i.e. short length), (42, n 51). Pedipalps as in gure 6d, e, h–k; P.II with a proximal spine-like seta on outer lateral face and a dorsodistal spine on inner lateral face; P.III with a long hair-like seta on outer lateral face and a shorter, stout seta distally on inner lateral face; P.IV with two to three short hair-like setae on outer lateral face and with a short ventrodistal projection bearing two ne setae; P.V ventrally strongly concave and distally multitoothed (gure 6h–k). Lengths of palp segments: P.I, 13 (12–15, 14, n 54); P.II, 95 (84–105, 95, n 55); P.III, 55 (51–63, 59, n 55); P.IV, 97 (96–105, 99, n 55); P.V, 66 (60–69, 64, n 55). Genital eld at posterior of body, terminal and extending on to dorsum (gure 6a, b); gure 6f shows genital eld of Prep. 1367 in posterior view. Genital eld (gure 6c, f) comprised of two pairs of genital plates; anterior plates each with three acetabula, setae-bearing portion of anterior genital plate may or may not be extended and bears two short, ne setae; posterior plates larger than anterior plates, each with four to ve acetabula and with posterior dorsally-directed setae-bearing extensions bearing three to four setae; gonopore slit-like and anked on either side by two well-separated long setae (gure 6f); genital eld length, (90, n 51), genital eld width, 135 (135–141, 138, n 52). Excretory pore slit-like and free in dorsal integument (gure 6a). Morphology and chaetotaxy of legs as illustrated in gures 7a–h, 8a, b. All legs, particularly III and IV-Legs, with numerous hair-like setae. IV-Leg.3–5 distally with stout curved setae (gure 7e–g). Claws of all legs with barely discernible terminal teeth. Lengths of leg segments: I-Leg.1–6:—(78, n 51), 84 (72–84, 81, n 54), 126 (120–126, 123, n 54), 162 (162–168, 163, n 54), 159 (156–162, 159, n 53), 96 (84–114, 99, n 54); II-Leg.1–6: 60 (n 51), 93 (90–102, 96, n 56), 150 (150, n 56), 192 (192–198, 194, n 56), 195 (192–210, 201, n 56), 129 (120–132, 123, n 56); III-Leg.1–6: 72 (72, n 53), 102 (102, n 56), 162 (156–168, 163, n 56), 197 (195–210, 200, n 55), 216 (216–240, 228, n 56), 156 (150–162, 156, n 55); IV-Leg.1–6:—(96–132, 120, n 53), 114 (114–126, 120, n 54), 180 (174–180, 178, n 54), 210 (210–216, 213, n 54), 258 (258–270, 265, n 54), 198 (198–216, 207, n 54).

Female (gures 9a–e, 10a–g). Body larger and rounder than that of male; length, excluding gnathosoma 976 (830–976, 927, n 53), width 646 (622–646, 638, n 53). Dorsum (gure 9a) with a dorsal shield, length 396 (396–492, 456, n 53), width 264 (264–318, 298, n 53). Ventrally with epimera in four groups, similar to those of male but with posterior groups more separated (gure 9b); total epimeral length 462 (462–558, 500, n 53), median length Ep.31 4, 294 (294–318, 306, n 53), median length Ep.4, 210 (210–234, 220, n 53); epimeral width at Ep.3, 426 (426–486, 458, n 53), epimeral width at Ep.4, 528 (528–576, 556, n 53). Infracapitulum and chelicerae similar to those of male, infracapitulum length 147 (147–159, 154, n 53), chelicera length 144 (144–156, 150, n 52), cheliceral claw length (dorsal, i.e. short length) 36 (–, 36, n 52). Pedipalps (gures 9d, e, 10b –g) similar to those of male, lengths of pedipalp segments: P.I, 12 (12–15, 13, n 55); P.II, 98 (96–111, 105, n 5 6); P.III, 63 (57–69, 65, n 56); P.IV, 99 (99–108, 105, n 56); P.V, 60 (60–69, 66, n 56). Genital eld more-or-less terminal (allotype female, Prep. 1369, tilted to show genital eld as depicted in gure 9b, c); gure 10a illustrates genital eld in ventral aspect. Genital eld consisting of two pairs of somewhat triangular wing-like genital plates; anterior plates each with two to ve, generally three, lateral acetabula, two to four short, ne setae on inner margin and posteromedially with two long setae on a strongly sclerotized projection (gures 9c, 10a); posterior genital plates each with ve to eight lateral acetabula, sclerotized setae-bearing (two to four) posterior extensions long and narrow (gure 9c) and anteromedially with a single stout seta (gures 9c, 10a); gonopore slit-like; genital eld length 192 (150–192, 171, n 52), genital eld width 204 (204–240, 224, n 53). Excretory pore slit-like and free in integument. Morphology and chaetotaxy of legs similar to those of male; IV-Leg.3–5 also as male with distal stout curved setae. Lengths of leg segments: I-Leg.1–6: 60 (60–66, 63, n 52), 78 (78–84, 80, n 53), 120 (120–126, 122, n 53), 156 (156–174, 162, n 53), 144 (144–168, 152, n 53), 90 (90–102, 94, n 53; II-Leg.1–6: 60 (60–69, 65, n 53), 90 (90–102, 97, n 55), 144 (144–156, 151, n 56), 186 (186–198, 194, n 56), 192 (192–210, 202, n 56), 123 (120–138, 128, n 56); III-Leg.1–6: 72 (72–78, 73, n 55), 102 (102–108, 103, n 56), 153 (150–162, 159, n 56), 192 (192–204, 200, n 56), 216 (216–234, 228, n 56), 153 (144–156, 151, n 55); IV-Leg.1–6: 126 (108–126, 121, n 54), 114 (114–132, 124, n 56), 168 (168–186, 177, n 56), 210 (210–234, 223, n 56), 252 (252–282, 270, n 56), 198 (198–216, 205, n 56).

Material examined. Three males: holotype, Prep. 1366; paratypes, Preps 1365 and 1367; three females : allotype, Prep. 1369; paratypes Preps 1368 and 1370. Several unmounted specimens preserved in Koenike’s Fluid. All material collected by Prof. John Blay from Asa Reservoir, Ilorin, Nigeria .

Etymology. The speci c epithet is formed from the latin words plane meaning distinctly and curvatus meaning curved. The name alludes to the strongly curved pedipalp tarsus (P.V).

Deposition of material. The holotypes and allotypes of Unionicola blayi and Unionicola planicurvata will be deposited in The Natural History Museum, London. Paratypes and material preserved in Koenike’s will be retained in the collection held by T.G.

Separation of U. blayi and U. planicurvata . Whilst closely related, the two species are readily separated; the main characters are found in the shape of the posterior margins of Ep.I: straight in U. blayi and rounded in U. planicurvata ; the curvature of the pedipalp tarsus (P.V): strongly curved in U. planicurvata ; the form of the setae-bearing extensions to the posterior pair of genital plates: long and narrow in U. planicurvata and more-or-less absent or short in the female of U. blayi and the presence, in U. planicurvata , of the stout, curved, distal setae on the telofemur, genu and tibia of the fourth leg (IV-Leg.3–5) which are absent in U. blayi .