Pentamerismus (Oligomerismus) retusus Meyer 1979
Creators: name: Mirza, Jawwad Hassan
name: Elgoni, Nasreldeen Ahmed
name: Kamran, Muhammad
name: Alatawi, Fahad Jaber
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Trombidiformes
Tenuipalpidae
Pentamerismus
Pentamerismus retusus

description: Pentamerismus (Oligomerismus) retusus Meyer, 1979
Pentamerismus retusus Meyer, 1979: 130, figs. 460–463; Meyer & Van Dis 1993: 323, figs. 57–58; Alatawi et al. 2015: 827.
Material examined. Six females (KSMAAS14-Ten-Pen-01–06) and three males (KSMAAS14-Ten-Pen-07–09), ex Zygophyllum simplex Linnaeus (Zygophyllaceae), Saudi Arabia, Riyadh province, King Saud University, near College of Food and Agriculture Science, 24°50’57’’ N, 46°33’149’’ E, 30 April 2014, coll. M. Kamran.
Complementary description of female (n=6)
Dorsum (Figure 1). Idiosoma oval in shape, length of body (excluding gnathosoma) 225 (212–237); (including gnathosoma) 275 (263–287) long; 127 (119–113) wide.
Anterior margin of dorsal propodosoma rounded with no anterior notch; dorsal propodosomal setae (v 2, sc 1, sc 2) subspatulate serrate; length of seta v 2 half as long as distance between setae v 2 –v 2; dorsal propodosoma with weak longitudinal striation medially; posterior opisthosoma entirely with longitudinal striations; transverse striation in line of setae d 1; medial striation between the setae c 1 and d 1 dome shape pattern, slightly irregular dorsolaterally; opisthosoma with three pairs of dorsocentral setae (c 1, d 1, e 1), two pairs of dorsolateral setae (c 2, d 2), seven pairs of dorsolateral setae (c 3, d 3, e 2, e 3, f 3, h 1, h 2); first row of dorsal opisthosomal setae c 1, c 2, c 3 subspatulate; other central and lateral dorsal opisthosomal setae broadly spatulate, becoming broader toward posterior; setae f 2 absent. Lengths of dorsal setae as follows: v 2 14–17, sc 1 18–22, sc 2 19–24, c 1 18–22, c 2 15–19, c 3 14–17, d 1 16–22, d 2 15–19, d 3 14–17, e 1 13 –18, e 2 13 –16, e 3 14 –19, f 3 10–14, h 2 10–14, h 1 10–15. Distances between dorsal setae: v 2 –v 2 33–39, v 2 –sc 1 25–30, sc 1 –sc 2 23–28, sc 1 –sc 1 63–72, sc 2 –sc 2 91–99, c 1 –c 1 41–47, c 1 –c 2 25–30, c 2 –c 3 11–15, c 2 –c 2 89–97, c 3 –c 3 118–129, c 1 –d 1 31–37, c 2 –d 2 33–43, c 3 –d 3 42–50, d 1 –d 1 35–40, d 1 –d 2 20–24, d 2 –d 3 13–15, d 2 –d 2 100–112, d 3 –d 3 105–114, d 1 – e 1 40–47, d 3 – e 3 18–22, e 1 – e 1 20–25, e 1 – e 2 35–42, e 2 – e 3 20–23, e 2 –e 2 105–113, e 3 –e 3 90–99, e 3 –f 3 20–25, f 3 –f 3 67–74, f 3 –h 2 19–24, h 1 –h 1 15–19, h 1 –h 2 15–20, h 2 –h 2 45–51, e 1 –h 1 42–49.
Venter (Figure 2). Ventral propodosoma with transverse striation; longitudinal striations between setae 3 a and 4 a, transverse striations posterior to 4 a and anterior to setae ag, immediately posterior to coxae IV with transverse striae laterally; oblique to transverse striae anterolateral to genital shield. Length of setae: 1 a 90–112, 1 b 19–26, 1 c 15–20, 2 b 16–20, 2 c 20–26, 3 a 15–22, 3 b 13–17, 4 a 15–20, 4 b 14–19, ag 17–22, g 1 14–19, g 2 16–20, ps 3 7–10, ps 2 9–13, ps 1 11–14. Ventral setae 1 a whip-like, three to four times longer than 3 a. Genital and anal shields coarsely striated (Figure 2A); aggenital setae (ag) serrated, equal in length to genital setae (g 1 – 2) also serrated; anal shields with three pairs of setae (ps 1–3), ps 1 –2 narrowly lanceolate. Distances between ventral setae: 1 a– 1 a 20–27, 3 a– 3 a 36–40, 4 a –4 a 26–33, 1 b –1 c 11–15, 2 b –2 c 20–22, 1 a –3 a 51–59, 3 a– 4 a 30–38, 4 a–ag 56–63, ag–ag 13–15, g 1 –g 1 15–20, g 2 –g 2 35–41, g 1 –g 2 10–13, ag–g 1 22–27, ag–g 2 21–28, g 1 –ps 1 32–38, g 1 –ps 2 30–37, g 1 –ps 3 8–32, g 2 – ps 1 37–44, g 2 –ps 2 30–34, g 2 –ps 3 27–32. Spermatheca globular elongate (Figure 2B).
Gnathosoma (Figure 3). Subcapitulum with one pair of setae m (Figure 3A) Rostrum reaching to the distal end of genu I; palp five segmented, palp tarsus with one solenidion and two eupathidia distally, where inner eupathidion is distinctly smaller; palp tibia with two setae, palp femur and genu without setae (Figure 3B).
Legs (Figure 4). Legs are short, less than one third the length of idiosoma; Length of leg I 78–85; leg II 66–71; leg III 70– 75; leg IV 71–78. Setal formulae of leg segments as follows: coxae 2-2-1-1; trochanters 1-1-2-1; femora 4-4-2-1; genua 2-2-0-0; tibiae 4-4-3-3; tarsi 8(1 ω)-8(1 ω)-5-5. Dorsal setae on femur I–III, genu I-II and tibiae I narrowly lanceolate and distinctly serrated (Figure 4). Tarsus I and II each with one antiaxial solenidion (ω) 10–12 and 8–10 long, respectively (Figure 4). Tarsal claws uncinate and empodia pad-like.
Description of male (n=3)
Dorsum (Figure 5). Idiosoma oval in shape, length of body (excluding gnathosoma) 144–149; (including gnathosoma) 197–200 long; width 83–88 wide. Anterior margin of dorsal propodosoma rounded with no anterior notch; dorsal propodosomal setae (v 2, sc 1, sc 2) subspatulate serrate; length of seta v 2 more than half the distance between setae v 2 –v 2; dorsal propodosoma with circular longitudinal striae becoming weak medially as in female; dorsal opisthosomal setae c 1–3 subspatulate; other dorsal opisthosomal setae broadly spatulate, becoming broader toward posterior; setae f 2 absent. Lengths of dorsal setae as follows: v 2 16 – 18, sc 1 15 – 18, sc 2 16 – 17, c 1 11 – 15, c 2 10 – 13, c 3 8 – 10, d 1 10–11, d 2 8–11, d 3 9–13, e 1 8 –13, e 2 10 –13, e 3 8 –10, f 3 10–11, h 2 10–12, h 1 9–11. Distances between dorsal setae: v 2 –v 2 23 – 25, v 2 –sc 1 16 – 18, sc 1 –sc 2 16 – 18, sc 1 –sc 1 46 – 49, sc 2 –sc 2 52–55, c 1 –c 1 26–29, c 1 –c 2 16 – 21, c 2 –c 3 8 – 9, c 2 –c 2 53 – 54, c 3 –c 3 71–75, c 1 –d 1 18–22, c 2 –d 2 21–23, c 3 –d 3 27–32, d 1 –d 1 24–25, d 1 –d 2 11–12, d 2 –d 3 8–10, d 2 –d 2 47–49, d 3 –d 3 65–66, d 1 – e 1 16–19, d 3 – e 3 34–35, e 1 – e 1 16–21, e 1 – e 2 15–16, e 2 – e 3 15–16, e 2 – e 2 48 – 50, e 3 – e 3 44 – 49, e 3 –f 3 8–10, f 3 –f 3 32 – 36, f 3 –h 2 11–12, h 1 –h 1 5–7, h 1 –h 2 7–8, h 2 –h 2 23–25, e 1 –h 1 29–31.
Venter (Figure 6). Ventral propodosoma and inter-coxal area between setae 1a and 3a with transverse striation; area between coxae III–IV with longitudinal striae, area posterior setae 4a with transverse striae. Length of setae: 1 a 42–49, 1 b 28–29, 1 c 22–25, 2 b 19–20, 2 c 18–21, 3 a 15–18, 3 b 13–17, 4 a 15–17, 4 b 13–15, ag 13–17, g 1 10–11, g 2 9–10, ps 3 10–11, ps 2 10–12, ps 1 9–11. Ventral setae 1a whip-like, three times longer than 3 a; aggenital setae (ag); genital setae serrated (g 1 – 2); anal shields with 3 pairs of serrated setae (ps 1 – 3). Distances between ventral setae: 1 a– 1 a 13–16, 3 a– 3 a 23–28, 4 a –4 a 16–18, 1 b –1 c 8–10, 2 b –2 c 15–17, 1 a –3 a 43–46, 3 a– 4 a 20–22, 4 a–ag 54–56, ag–ag 11–13, g 1 –g 1 6–7, g 2 –g 2 14–16, g 1 –g 2 4–5, ag–g 1 24–26, ag–g 2 28 – 33 (Figure 6A). Aedeagus (Figure 6C) long, pointed at tip.
Gnathosoma (Figure 6B). Rostrum reaching to the distal end of genu I; palp (Figure 6B) 5 segmented, palp tarsus with one solenidion and two eupathidia distally; palp tibia with two setae, palp femur and genu without setae.
Legs (Figure 7). Legs are short, less than half length of idiosoma; Length of legs measured from (trochanter to tarsus), leg I 66–67; leg II 61–62; leg III 59–60; leg IV 64–66. Setal formulae of leg segments as follows: coxae 2-2-1-1; trochanters 1-1-2-1; femora 4-4-2-1; genua 2-2-0-0; tibiae 4-4-3-3; tarsi 8(1 ω)-8(1 ω)-5-5. Tarsus I and II each with one antiaxial solenidion (ω”) 8 (7-8), 7 (6–7) long. Tarsal claws uncinate and empodia pad-like.
Remarks. The Saudi specimen of Pentamerismus (Oligomerismus) retusus morphologically resembles the original (Meyer 1979; South Africa) and supplementary descriptions (Meyer 1993; Namibia). The Saudi specimens were compared with the images of the holotype of P. (O.) retusus. The dorsomedial striae on propodosoma are longitudinal and weak in Saudi specimens (female and male), while in compared specimens, striae form a circular pattern (Meyer 1979, holotype) or surface is rugose (Meyer 1993). The pattern of striation between setal rows C and D in our specimens is mostly transverse with a small region of arched striae compared to irregular to transverse striaein the holotype (Meyer 1979). The propodosomal setae of Saudi specimen (female and male) are subspatulate serrate in shape compared to broadly spatulate (Meyer 1979) and broadly lanceolate to subspatulate (Meyer 1993). The length of dorsal propodosomal setae v 2 is half the distance v 2 –v 2 compared to one third in the holotype (Meyer 1979, 1993).
description: Published as part of Mirza, Jawwad Hassan, Elgoni, Nasreldeen Ahmed, Kamran, Muhammad & Alatawi, Fahad Jaber, 2025, Subgenera of the genus Pentamerismus McGregor (Acari: Tenuipalpidae) with the re-description of Pentamerismus retusus Meyer and a key to species of the world, pp. 143-156 in Zootaxa 5601 (1) on pages 146-153, DOI: 10.11646/zootaxa.5601.1.7, http://zenodo.org/record/14980641