Arrenurus (Arrenurus) munovus Cook 1980
Creators: name: Ramírez-SánchezK, Marcia M.
name: GoldschmidtK, Tom
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Trombidiformes
Arrenuridae
Arrenurus
Arrenurus munovus

description: Additional description of Arrenurus (Arrenurus) munovus Cook 1980
Diagnosis
Yellow with bluish pattern (Figs 2A, 3 and 7); males with relatively short pygal lobes (not projecting beyond the base of the petiole), petiole relatively long and slender (Figs 2A, 4A,
5A and 5B), male acetabular fields medially broader than the genital opening, stretching out nearly perpendicular, continuously tapering towards lateral idiosoma margin (Fig. 5B); females with acetabular fields oval-drop shaped, from anterior half of genital field stretching to postero-lateral (Fig. 10B); palps with very subtle or none sexual dimorphism– P-4 rather compact, bearing two medio-dorsal setae, antagonistic setae ventro-distally at medial side of
P-4 strong, 1.5 fold longer than P-5, additional small bristle at ventro-distal tip of P-4; however P-2 medially with three setae in the illustrated male from Belize (four in the male illustrated in the species description from Mexico), but five in the illustrated female from Belize (Figs 5C, 5D, 10E and 10F).
Male (n = 2 (1 partly dissected))
Idiosoma yellow, posterior bluish; legs and palps bluish. Frontal margin straight; dorsal furrow complete (Figs 2A and 3). Idiosoma dorsal L 893 (929); W 653 (696); dorsal shield L 513 (686), W 409 (442). Distance between the anterior idiosoma margin and the anterior dorsal shield outline (maximum curvature) 210 (240); distance between the lateral dorsal shield outline (shortest distance) and the lateral depression anterior to the postero-lateral protrusion 104 (120); distance between the lateral dorsal shield outline (shortest distance) and the postero-lateral protrusion 125 (135). Non-caudal portion of dorsal shield L 395 (403); cauda L 286 (288), proximal W 269 (269), maximum W (between outer margins of pygal lobes) 311 (318); caudal margin between pygal lobes concave, with small protrusions at the base of pygal lobes, median projection distally pointed, with hyaline tip, basally constricted (Fig. 4B); petiole elongated, basally relatively straight, distally diverging towards two fin-like elevated projections (Figs 3 and 4A); petiole proximal W 69 (67), maximum W 90 (106), L 165. Distances between glands and setae of dorsal glandularia (between the glands/setae of both sides, respectively two different glandularia of one idiosoma side): A1, glands 226 (235); A1, setae 249 (259); A2, glands 193 (192); A2, setae 172 (183); R1 190 (197); R2 127 (154); Dgl-1, glands 492 (542); Dgl-1, setae 488 (528); Dgl-2, glands 320 (336); Dgl-2, setae 288 (302); Dgl-3, glands 122 (134); Dgl-3, setae 82 (91); Dgl-4, glands 87 (96); Dgl-4, setae 33 (43); Lgl-1, glands 441 (470); Lgl-1, setae 406 (442); Lgl-2, glands 571 (590); Lgl-2, setae 566 (586); Lgl-3, glands 611 (653); Lgl-3, setae 625 (662); Lgl-4, glands 260 (269); Lgl-4, setae 273 (284). R2—Dgl-2 (seta) 113 (120); Dgl-2—Dgl-3 (glands) 156 (154); Dgl-2—Dgl-3 (glands) 156 (154); Dgl-2—Dgl-3 (setae) 125 (118); Dgl-3—Dgl-4 (glands) 155 (149); Dgl-3—Dgl-4 (setae) 173 (177).
Ventral shield L 904 (951), W 650 (680); distance between Cx-I tips 187 (191); coxal field L 523 (548), W 642 (685) (measured between Cx-IV tips) (Figs 2B, 5A). Acetabular plate region W 373 (406); gonopore inner L 40 (44), outer L 46 (48); inner W 17 (14), outer W 35 (38) (Fig. 5B). Distances between glands and setae of ventral glandularia: Cxgl-1, glands 321 (327); Cxgl-1, setae 304 (318); Cxgl, -2 glands 161 (169); Cxgl-2, setae 144 (147). V1 (setae) 149 (151); V2, glands 111 (107); V2, setae 147 (148); V3 (setae) 201 (232); V4, glands 401 (427); V4, setae 342 (374). Barely two rows of body pores between the anterior and posterior coxal groups, left and right posterior coxae medially touching each other (Figs 2B and 5A).
Palp segments, L/H: P-1, 29/34; P-2, 69/58; P-3, 53/56; P-4, 79/50; P-5, 40/16; P-2 stocky, with three medial setae; disto-ventral portion of P-4 slightly angular with one large antagonistic seta, L 57 (Figs 5C and D).
Leg segments, L/H: I-leg-1, 47/54; I-leg-2, 64/52; I-leg-3, 94/49; I-leg-4, 112/51; I-Leg-5, 117/48; I-Leg-6, 126/33 (Figs 6A, B). II-leg-1, 57/59; II-leg-2, 78/54; II-leg-3, 106/53; II-leg-4, 130/51; II-Leg-5, 139/47; II-Leg-6, 147/33 (Fig. 6C). III-leg-1, 78/80; III-leg-2, 100/52; III-leg-3, 114/54; III-leg-4, 152/53; III-Leg-5, 156/49; III-Leg-6, 152/39 (Fig. 6D). IV-leg-1, 134/86; IV-leg-2, 185/77; IV-leg-3, 179/68; IV-leg-4, 242/65; IV-Leg-5, 97/44; IV-Leg-6, 96/30 (Figs 6E and 6F). I-leg-2, 3 with long stiff serrate setae (Figs 6A and 6B); III-leg bearing both long stiff setae and swimming setae (Fig. 6D); IV-leg-2 with long stiff serrate setae; IV-leg-3 with both short and long stiff serrate setae, and swimming setae ventro-distally; IV-leg-4 with a long distal process [sometimes named ‘spur′] (total L 122); IV-leg-4 and IV-leg-5 bearing swimming setae along the ventral surface – in groups of eight to ten posterior and anterior in distal half and at the ventro-distal process of IV-leg-4, and posterior in distal 2/3 of IV-leg-5 (Fig. 6F).
Female (n = 5 (1 partly dissected))
Idiosoma yellow, posterior bluish (Figs 7 and 8); legs and palps bluish. Frontal margin slightly convex; dorsal furrow complete; idiosoma margin rounded (Figs 7A, 8, 10A and
10C). Idiosoma L 760 (763–878); W 669 (668–755). Dorsal shield L 493 (499–619), W 410 (394–485). Distance between the anterior idiosoma margin and the anterior dorsal shield outline (maximum curvature) 231 (211–250); distance between the lateral idiosoma margin and the lateral dorsal shield outline, at Lgl-2, 131 (130–144); distance between the lateral idiosoma margin and the lateral dorsal shield outline at Lgl-3, 79 (67–91); distance between the posterior idiosoma margin and the posterior dorsal shield outline (maximum curvature) 44 (38–62). Distances between glands and setae of dorsal glandularia (between the glands/setae of both sides, respectively two different glandularia of one idiosoma side): A1, glands 215 (230–254); A1, setae 241 (250–284); A2, glands 181 (198–216); A2, setae 159 (173–192); R1
180 (197–214); R2 153 (149–182); Dgl-1, glands 475 (470–518); Dgl-1, setae 480 (461–514); Dgl-2, glands 286 (278–341); Dgl-2, setae 254 (245–326); Dgl-3, glands 258 (240–293); Dgl-3, setae 223 (202–272); Dgl-4, glands 200 (163–197); Dgl-4, setae 167 (139–173); Lgl-1, glands 463 (461–528); Lgl-1, setae 428 (427–509); Lgl-2, glands 671 (662–739); Lgl-2, setae missing (643–720); Lgl-3, glands 513 (461–566); Lgl-3, setae missing (480–576); Lgl-4, glands 197 right palp, medial. Scale bar = 100 µm.
(173–223); Lgl-4, setae missing (211–254). R2—Dgl-2, seta 64 (64–96); Dgl-2—Dgl-3, glands 200 (182–219); Dgl-2—Dgl-3, setae 196 (186¬–211); Dgl-3—Dgl-4, glands 136 (144–182); Dgl-3—Dgl-4, setae 127 (127–178).
Ventral shield L 798 (782–883), W 677 (662–756); distance between Cx-I tips 176 (177– 194); coxal field L 471 (466–514), W 644 (624–720) (measured between Cx-IV tips) (Figure 10B). Acetabular plates region W 480 (451–514); gonopore inner L 124 (113–133), outer L
139 (141–154); W 157 (130–166). Distances between ventral glandularia (glands and setae): Cxgl-1, glands 298 (298–341); Cxgl-1, setae 286 (284–326); Cxgl-2, glands 236 (226–307); Cxgl-2, setae 217 (197–298). V1, setae 130 (110–120); V2, glands 187 (163–202); V2, setae 210 (192–237); V3, setae 307 (278–317); V4, glands 516 (494–586); V4, setae 534 (504–605); V1—V2 (setae) 48 (43–63). Barely two rows of (small) body pores between the anterior and posterior coxal groups, two rows between left and right Cx-III, one row between Cx-IV (Figs
7B, 10A and 10B).
Palp segments, L/H: P-1, 28/38; P-2 69/60; P-3, 49/53; P-4, 80/49; P-5, 41/18; structure and chaetotaxy of the palps as described for the male; P-4 distoventral portion slightly angular with one large antagonistic seta, L 60 (Figs 10E and 10F).
Leg segments, L/H: I-leg-1, 51/51; I-leg-2, 59/51; I-leg-3, 90/48; I-leg-4, 107/50; I-Leg-5, 111/45; I-Leg-6, 106/34 (Fig. 11A). II-leg-1, 55/57; II-leg-2, 71/52; II-leg-3, 97/51; II-leg-4, 122/50; II-Leg-5, 128/45; II-Leg-6, 115/33 (Fig. 11B). III-leg-1, 66/67; III-leg-2, 82/48; III-leg-3, 100/51; III-leg-4, 132/49; III-Leg-5, 137/46; III-Leg-6, 121/33 (Fig. 11C). IV-leg-1, 105/64; IV-leg-2, 146/54; IV-leg-3, 126/53; IV-leg-4, 164/43; IV-Leg-5, 144/37; IV-Leg-6, 123/28 (Figs 11D – G). III-leg 2–4 bear stiff serrate setae; III-leg-5, 6 bear long stiff setae (Fig. 11C); IV-leg-2–4 bear numerous long serrate setae; IV-leg-3–5 bear swimming setae (Figs 11D – G).
Remarks
As has been observed in other Arrenurus subgenera (such as Megaluracarus), morphological boundaries between males can be subtle and difficult to establish, then a thorough inspection of different type of characters is needed and, if the female is available, it must be included. In the case of Arrenurus (s.s.) some species show very stout anterior idiosoma and both, well developed pygal lobes and petiole while others show a combination of different grades of development of those features (Marshall 1908 ; Cook 1974).
Differential diagnosis of the male of A. (A.) munovus within the so far known Central American species of the subgenus Arrenurus
In A. (A.) munovus the pygal lobes are relatively short (not projecting beyond the base of the petiole), the petiole is relatively long. The only other species with similar short pygal lobes A is. valencius, however in this species the petiolus is bearing a characteristically long and slender tip (Böttger 1980). In A. dentipetiolatus, tamaulipensis and xochimilcoensis the pygal lobes are clearly longer and the petiole considerably shorter (Cook 1980 ; Cramer and Cook 1992). In A. wucabus the petiole has approximately the same length and a slightly similar shape, however the pygal lobes are longer and more pronounced; additionally A. wucabus lacks a pointed medial protuberance just above the petiole present in A. munovus (Cook 1980).
Differential diagnosis of the female of A. (A.) munovus within the so far known Central American species of the subgenus Arrenurus
Females of the Central American species can be separated by the shape of the acetabular plates, as well as the setation of the medial side of P-2: As far as known A. munovus is the only species (no respective illustrations were available for A. dentipetiolatus, the female of A. wucabus is unknown) of this group with the acetabular plates broad and curved (with a clear bend of ~50°) from the anterior part of the genital field towards posterior. In A. valencius the acetabular plates are located besides the posterior half of the genital field, posteriorly extending clearly beyond the genital field and are regularly curved from posterior to lateral (Marshall 1908); in A. tamaulipensis the acetabular plates show a postero-lateral curve very similar to the latter species, however with a more regular curve and not extending so far towards postero-medially of the genital field (Cramer and Cook 1992); A. xochimilcoensis is clearly separated from the other species of this group by relatively narrow acetabular plates, extending from the gonopore towards slightly towards antero-lateral (Cramer and Cook 1992).
The palps of A. munovus are bearing four setae on the medial surface of P-2 and one medio-dorsally; in the description of A. valencius no setae are visible in the respective position, however Orghidan and Gruia (1977) are illustrating five medial and one medio-dorsal setae at P-2, whereas Lundblad (1935) is giving an illustration with just three medial setae at P-2; in A. dentipetiolatus P-2 is bearing four medial setae; in A. tamaulipensis there are two and in A. xochimilcoensis two medial and one medio-dorsal setae at P-2 (Cramer and Cook 1992).
description: Published as part of Ramírez-SánchezK, Marcia M. & GoldschmidtK, Tom, 2024, First record of the water mite species Arrenurus (Arrenurus) munovus Cook, 1980 from Belize, including the description of the female (Arrenuridae, Hydrachnidia, Acari), pp. 865-878 in Acarologia 64 (3) on pages 868-875, DOI: 10.24349/vzqw-26ua, http://zenodo.org/record/14670302