Mirza, Jawwad Hassan ¹ ; Kamran, Muhammad ² ; Khan, Eid Muhammad ³ and Alatawi, Fahad Jaber ⁴

¹Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia.
²Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia.
³Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia.
⁴✉ Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia.

2025 - Volume: 65 Issue: 3 pages: 815-826

Original research

Keywords

Abstract

Introduction

Africoseiulella Kreiter (Parasitiformes: Phytoseiidae) is a unique genus represented by two species, A. flechtmanni Kreiter (Southern Tunisia: Kreiter and Tixier 2006) and A. sedisazlensis El-Banhawy, Nasr & Ramadan (Egypt: El-Banhawy et al. 2025). It belongs to the tribe Metaseiulini Chant & McMurtry in the subfamily Typhlodrominae Wainstein (Kreiter and Tixier 2006). The validity of the genus Africoseiulella was well supported by comprehensive systematic and phylogenetic analysis (Kreiter and Tixier 2006).

Negm and Alatawi (2013) described Nabiseius arabicus Negm & Alatawi (Parasitiformes: Otopheidomenidae) collected from Cynodon dactylon L. (Poaceae) in a date palm (Phoenix dactylifera L.; Arecaceae) orchard from Saudi Arabia. A re-evaluation of the type specimens of this species and additional specimens collected in the present study was conducted to ascertain its generic placement. The objective of this study was to provide a complementary description of Africoseiulella arabicus comb. nov. (Negm & Alatawi, 2013) female, in addition to the description and illustrations of male. Some inconsistencies are discussed as found between the specimens and the description of the species by Negm and Alatawi (2013). Furthermore, some of the morphological characters as found in the A. arabicus comb. nov. female are discussed for their taxonomic significance.

Material and methods

The 15 female type specimens of A. arabicus comb. nov. were re-examined. Two males were collected with the same field data as that of females, but had not been previously described, and were also analyzed in the present study. Additionally, occasional field visits resulted in the collection of additional specimens (both females and male) of same species from different localities of Saudi Arabia. The specimens were collected by shaking the plant foliage on a white sheet of paper and preserved in labelled 1.5ml Eppendorf tubes filled with 70% ethanol. In the laboratory, these were mounted on glass slides in Hoyer's medium and examined under a phase contrast microscope (DM2500, Leica, Wetzlar, Germany). The DIC images of different body parts were photographed using an Auto-montage Software System (Syncroscopy, Cambridge, UK), which were used as template to be illustrated with Adobe Illustrator (Adobe System Inc., San Jose, CA, USA). All measurements are given in micrometers. The terminology used in this study follows that of Rowell et al. (1978) for the dorsum and Chant and Yoshida-Shaul (1991) for the venter. The leg setal notation followed Evans (1963) while those of lyrifissures followed Athias-Henriot (1975). The identification of the genus Africoseiulella followed the characterization of Kreiter and Tixier (2006), based on the system of Chant and McMurtry (1994). All specimens have been deposited at King Saud University Museum of Arthropods (KSMA), Acarology section, Department of Plant Protection, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia.

Taxonomy

Based on the examination of the type specimens of Nabiseius arabicus Negm & Alatawi, 2013 and the new specimens collected from different regions of Saudi Arabia, it is now assigned to the genus Africoseiulella, in the family Phytoseiidae, as A. arabicus comb. nov. This genus is reported for the first time from Saudi Arabia, with the complementary description of female, in addition to the description and illustrations of male. Also, some inconsistencies are discussed as found between the specimens and the description of the species by Negm and Alatawi (2013).

Africoseiulella Kreiter

Africoseiulella Kreiter in Kreiter and Tixier 2006: 3.

Type species — Africoseiulella flechtmanni Kreiter, in Kreiter and Tixier 2006: 6 (by original designation).

Diagnosis — as defined by Kreiter and Tixier 2006.

Africoseiulella arabicus (Negm & Alatawi) comb. nov.

Nabiseius arabicus Negm & Alatawi 2013: 2.

Updated Diagnosis

Female: sternal shield reticulate bearing setae st1-2 and lyrifissures iv1-2, fixed cheliceral digit with apparently two teeth, a pilus dentilis reduced to base, and a hyaline flap; Male: seta s4 distinctly inserted in lateral integument, genitoventral shield bearing st1-3 and iv1-2, ventrianal shield seemingly split into three fragments, the laterals seemingly fused with metapodal plates.

Female (Figures 1-5) (n = 34)

Dorsal idiosoma (Figure 1A-B) — Dorsal shield 275–282 long and 121–126 wide at the level of setae s6, with diagonal mostly parallel striae over most of its extent, but smooth centrally posteriad j6, distinctly eroded anteriad insertion of S2, deeply incised immediately posteriad s6, rounded posteriad S2 where it covers the whole dorsum; punctations scattered from j1 to anterior of j6 medially and till z5 laterally. Some scattered muscle marks (sg: sigilla) posterior to J2, bearing 17 pairs of short, smooth and needle-like setae of the following numbers and length; seven pairs in j-J series: j1 4–5, j3 8–9, j4 6–8, j5 4–6, j6 7–9, J2 7–8, J5 3–5, six pairs in z-Z series: z2 7–9, z3 6–8, z4 8–10, z5 8–9, Z4 8–10, Z5 7–9; four pairs in s-S series: s4 8–10, s6, 6–8, S2 6–7, S5 6–8; one pair in r-R series: r3 7–8, inserted in unsclerotized lateral integument, solenostomes absent, eight pairs of lyrifissures evident.

Ventral idiosoma (Figure 2A-B) — Tritosternum with base 15–16 wide, but otherwise similar to the most Mesostigmata, with serrated laciniae, divided for about 60% of their total length (tip to base). Sternal shield 68–72 long, 41–44 wide at st2 level; widening posteriorly between transverse anterior margin and insertion of iv2; posterior section constituting a pronounced rounded posterior lobe; reticulate anteriad st2, bearing setae st1 16–18, st2 15–17 on shield edges, and two pairs of lyrifissures (iv1 and iv2), setae, st3 15–17, st4 14–17, and iv3 inserted in unsclerotized cuticle. Genital shield 92–101 long along midline, 44–48 wide at level of setae st5; with rounded membranous anterior margin with elongate longitudinal cells, bearing one pair of setae, st5 15–16, on lateral edges of shield. Two pairs metapodal plates present; primary 34–36 long, accessory 6–8 long, a pair of lyrifissures anterior to setae ZV3, a pair lateral, and a pair posterior to JV5. Four transverse platelets present between genital and ventrianal shields. Ventrianal shield 72–74 long and 45–47 wide at the widest level, slightly concave anteriorly, pregenital pore absent, two pairs of pre-anal setae, ZV2 9–11 and JV2 9–11, one pair of para-anal setae 12–14 and a post-anal seta 11–12. Two pairs of opisthogastric setae, ZV3 10–11 and JV5 9–10, inserted in unsclerotized cuticle.

Peritreme (Figure 2A) — Peritremes short, 40–42 in length, reaching only to the anterior margin of coxae III, a pair of lyrifissure (id3) present dorsally on the peritremal shield.

Spermatheca (Figure 3A-D) — Calyx funnel-shaped (Figure 3B), with the dish-shaped (Figure 3C) section near vesicle sometimes indistinct (Figures 3A, D), 13–16 in length; atrium discernible, 5–7 distant from calyx, to which it is linked by a neck; major duct flaring from the sperm induction pore toward calyx.

Chelicera (Figure 4A-H) — Movable digit 12–14 long, toothless, with a large median lobular projection; fixed digit 13–15 long, apparently with two basal teeth; pilus dentilis represented only by its base, and a hyaline sheath, lateral to moveable digit (Figure 4A, B).

Legs (Figure 5A-D) — Number of setae on legs I–IV: coxae 2–2–2–1; trochanters 5–5–4–4; femora 11–9–6–6; genua 8–6–6–7; tibiae 8–7–7–6; basitarsi 1–2–2–1, telotarsi II-IV 13–13–10, macroseta absent on all legs.

Male (Figures 6-9) (n = 3)

Dorsal idiosoma (Figure 6) — Dorsal shield similar to that of female, but slightly narrower, so that in addition to r3, seta s4 is also inserted in the unsclerotized cuticle. Also differently from female, diagonal parallel striae only distinguishable in anterolateral region of opisthonotum (next to S2 with an unsclerotized ellipsoidal patch at setae z3); 240–248 long and 115–118 wide at the level of setae s6, bearing 16 pairs of simple setae, similar in shape to those of female, of the following number and length: seven pairs in j-J series: j1 7–8, j3 9–10, j4 8–9, j5 5–6, j6 6–7, J2 6–7, J5 3–4; six pairs in z-Z series: z2 9–10, z3 8–10, z4 9–10, z5 8–9, Z4 7–8, Z5 8–9, four pairs in s-S series s4 9–10, s6 7–8, S2 8–9, S5 7–8; one pair in r-R series: r3 7–8, both setae s4 and r3 clearly on striate lateral integument, off the dorsal shield; lyrifissures difficult to discern.

Ventral idiosoma (Figure 7) — Tritosternum with base 14–15 wide, with a pair of somewhat thick serrated laciniae than those of female, divided for about 75% of their total length (tip to base). Sternogenital shield smooth 118–120 long, 47–49 wide at widest point in between st2 and st3, bearing three pairs of smooth setae on shield edges (st1 14–15, st2 11–12 and st3 11–12) and two pairs of lyrifissure (iv1 and iv2). Setae st4 (10–11), genital setae st5 (11–12) and lyrifissure iv3 inserted in the unsclerotized cuticle. Ventrianal shield seemingly split into three fragments: two laterals with scant striae probably fused with metapodal plates, subtriangular in shape, each bearing a lyrifissure and a member of setae ZV3 on the edge, the central smooth 77–80 long and 52–54 wide, preanal pores absent, two pairs of pre-anal setae (ZV2 10–12 and JV1 8–10), one pair of para-anal setae 10–11 and a post-anal seta 7–8, setae JV5 7–8 and a lyrifissures in unsclerotized cuticle.

Peritreme — Peritremes short, 28–30 in length, extending to the posterior half of the coxae III.

Chelicera (Figure 8) — Movable digit 12–13 long, toothless; fixed digit 14–15 long, apparently with a tooth visible posterior to pilus dentilis, the latter represented only by its base; spermatodactyl shaft 7–8 long, ending in a foot shaped structure having a sub-terminal short rounded structure and a distal, rounded structure.

Legs (Figure 9) — As in female.

Material Examined

Fifteen females (KSMAAS11-Phy-Afr-F1-15) and two males (KSMAAS11-Phy-Afr-M1-2), on aerial part of Cynodon dactylon L. (Poaceae) in a date palm orchard, 24°48′N, 46°42′E, 645 m, Riyadh, 12 Jul. 2011, coll. Mohamed W. Negm; ten females (KSMAAS14-Phy-Afr-F16-25) and a male (KSMAAS11-Phy-Afr-M3), unidentified weeds, 24°48′32.7″N, 46°42′03.5″E, Imam Muhammad Bin Saud University, Riyadh, 2 Apr. 2014, coll. M. Kamran; nine females (KSMAAS24-Phy-Afr-F26-34), Chenopodium sp., 18°33′28.6″N, 41°55′53″E, Asir, 27 Apr. 2024, coll. N.A. Elgoni.

Morphological inconsistencies between original description of A. arabicus female and specimens

Some inconsistencies were found related to the ventral idiosomal and cheliceral morphology and leg chaetotaxy between the published description (Negm and Alatawi 2013) and all specimens examined in the present work. The female sternal and genital shields were reported as smooth, fixed digits of chelicerae having one tooth, and pilus dentilis absent. However, in this work, all the specimens were found to have sternal shield partially reticulated and the genital shield with elongate cells (Figure 2), fixed digit with two teeth, and only the base of the pilus dentilis present (Figure 4). Moreover, the leg chaetotaxy was contrastingly reported as coxae II-III with 1-1 (vs. 2-2 in specimens here examined), trochanters I-IV with 4-3-4-4 (vs 5-5-4-5), femora II-IV with 8-5-5 (vs. 9-6-6), genua I and IV with 9 and 6 (vs. 8 and 7), tibia IV with 5 setae (vs. 6 setae). Additionally, the dorsal setae Z3 and ventral opisthogastic setae JV4 were incorrectly named, while they should be Z4 and JV5, respectively.

Differential Remarks

Africoseiulella arabicus comb. nov. is morphologically close to A. sedishazlensis El-Banhawy, Nasr & Ramadan (El-Banhawy et al. 2025) due to presence of setae st3 and st4 off the sternal shield, presence of accessory metapodal plate, absence of tooth on moveable digit in female. However, A. arabicus comb. nov. could be distinguished from the later by following morphological differences. Female: ventrianal shield without pores (vs. with pores in A. sedishazlensis), sternal shield without distinct extension between coxae I-II (vs. with distinct extension between coxae I-II), fixed digit with two teeth (vs. with four teeth), number of setae on genu-tibia I 8-8 (vs 10-10), basitarsus I, IV 1, 1 (vs. 0, 2). Male: st3 on the sternogenital shield (vs. off the sternogenital shield), ventrianal shield fragmented (vs. unfragmented), spines on coxae III-IV absent (vs. spines present on coxae III-IV).

Africoseiulella arabicus comb. nov. also differentiates from the type species A. flechtmani Kreiter (in Kreiter and Tixier 2006), as follows. Female: st3 setae off the sternal shield on soft cuticle (vs on the sternal shield in A. flechtmani), sternal shield reticulated (vs. smooth), two pairs of metapodal platelets (vs one), fixed cheliceral digit with two median teeth (vs. edentate). Male: setae s4 clearly off the dorsal shield (vs. on the shield), anterior margin of sternogenital shield slight convex (vs with an acuminate protrusion), two pairs of lyrifissures on shield (vs one pair).

Additional Remarks

In the present work, A. arabicus comb. nov. was described with some morphological characters which were either unique for the genus Africoseiulella or even for the family Phytoseiidae itself. This genus has unique set of characteristics, as already well debated by Kreiter and Tixier (2006), to find its proper place in the family Phytoseiidae. The description of A. arabicus comb. nov. would not be an exception. The following characters are, therefore, discussed:

Hyaline sheath of the chelicera in the female — A hyaline sheath, folded between the cheliceral digits, was clearly visible in all specimens of A. arabicus comb. nov female (Figure 4A-H). At a certain resolution of observation, it appears as if present only distally on the fixed cheliceral digit (Figure 4E). A similar feature was described and illustrated by Negm and Alatawi (2013). In some other specimens, this sheath seems to cover most of the chelicerae from the movable digit side (Figure 4B). It is as if tightly packed and folded between the closed cheliceral digits (Figure 4C-H), but expanded upon forced opening of the chelicerae (Figure 4A-B). In A. sedishazlensis, the presence of leaf-like pilus dentilis is described. However, such a feature has not been described in the type species, A. flechtmanni nor has it been reported in the diagnosis of the genus Africoseiulella. Flechtmann et al. (1994) described the presence of cheliceral lobes as one of the rare features in the family Phytoseiidae, with an example of Phytoseiulus longipes Evans. However, this hyaline sheath in the A. arabicus comb. nov.chelicerae do not resemble those cheliceral lobes. Similarly, it does not appear as a modified shape of pilus dentilis as described for A. sedishazlensis. It is yet unclear what purpose it serves. Perhaps, scanning electron microscopic studies on this character in the future may prove fruitful to decide its taxonomic significance and functional morphology.

Number of teeth on the cheliceral digits — The genus diagnosis of Africoseiulella reports the presence of edentate cheliceral digits. However, in the type species, the fixed cheliceral digit of the male was reported to have one tooth. In contrast, A. sedishazlensis was reported with four teeth on fixed digit and a toothless moveable digit in female. With the transfer of A. arabicus comb. nov. this generic diagnostic character might be excluded, as this species also has dentate cheliceral digits. This feature also corresponds to the distinct morphological difference among the mentioned species. It is also important to remember that original description of A. arabicus comb. nov — lacks the description of any tooth presence on the cheliceral digits (Negm and Alatawi 2013) which is now corrected in the present work.

Base of the pilus dentilis, despite the absence of the actual pilus dentilis — Strangely enough, the actual pilus dentilis in A. arabicus comb. nov. is absent, but its base is rather distinct. Negm and Alatawi (2013) mentioned in the original description of A. arabicus comb. nov. the entire absence of pilus dentilis. Additionally, A. flechtmanni's description lacks the detail on this feature, too (Kreiter and Tixier 2006). This feature is not uncommon in the family Phytoseiidae (Flechtmann and McMurtry 1992) and was reported in P. longipes (Flechtmann et al. 1994). The explanation for this morphological feature (absence of pilus dentilis) was correlated with the presence of large cheliceral lobes. In A. sedishazlensis, the pilus dentilis was reported as leaf-like. However, it is not the case with A. arabicus and possible explanation may require further studies.

Leg chaetotaxy both in female and male — The leg chaetotaxy of some leg segments in A. arabicus comb. nov. (both sexes) follow what is usually reported for the free living gamasina in reference to the family Phytoseiidae (Evans 1963). However, some differences from the usual were also found. Generally, the leg chaetotaxy of coxae I-IV, trochanter II, femora III-IV, genu III and tibiae II-IV are same as reported by Evans (1963). The differences were found in number of setae on trochanter I, III, IV (5-4-4 in A. arabicus comb. nov. vs. 6-5-5 by Evans 1963), femora I-II (11-9 vs 12-10), genua I, II, IV (8-6-7 vs 10-7-10) and tibia I (8 vs. 10). Kreiter and Tixier (2006) only described number of setae on leg genua II and III as six each, for A. flechtmanni which is similar to the corresponding leg segments in all specimens of A. arabicus comb. nov. Here only chaetotaxy of genu III in both species does not match with Evans (1963) report. Similarly, the reduction of setae on certain leg segments were also reported for A. sedishazlensis (El-Banhawy et al. 2025). It might be possible that the Africoseiulella species represent a new chaetotaxy for the family Phytoseiidae which may help in better understanding of the taxonomy and systematics of the family group.

Funding

The authors would like to extend their sincere appreciation to the Ongoing Research Funding program (ORF-2025-807), King Saud University, Riyadh, Saudi Arabia, for funding this research.

Acknowledgements

The authors would like to extend their sincere appreciation to the respected reviewers whose constructive comments and corrections have improved this research. The authors are also thankful to Muneeb ur Rehman (Acarology Research Lab., King Saud University) for his technical support.

Conflict of Interest

The authors declare no conflict of interest exists

References

1. Athias-Henriot C. 1975. Nouvelles notes sur les Amblyseiini. II. Le relevé organotaxique de la face dorsale adulte (Gamasides, Protoadéniques, Phytoseiidae). Acarologia, 17: 20-29.
2. Chant D.A., McMurtry J.A. 1994. A review of the subfamilies Phytoseiinae and Typhlodrominae (Acari: Phytoseiidae). Int. J. Acarol., 20: 223-310. https://doi.org/10.1080/01647959408684022
3. Chant D.A., Yoshida Shaul E. 1991. Adult ventral setal patterns in the family Phytoseiidae (Acari: Gamasina). Int. J. Acarol., 17: 187-199. https://doi.org/10.1080/01647959108683906
4. El-Banhawy E.S.M., Nasr A.K., Ramadan M.M. 2025. Description of a new species of Africoseiulella Kreiter (Acari: Phytoseiidae) from Egypt. Zootaxa, 5633(2): 244-250. https://doi.org/10.11646/zootaxa.5633.2.2
5. Evans G.O. 1963. Observations on the chaetotaxy of the legs in the free-living Gamasina (Acari: Mesostigmata). Bull. Brit. Mus. (Nat. Hist.), 10: 275-303. https://doi.org/10.5962/bhl.part.20528
6. Flechtmann C.H.W., McMurtry J.A. 1992. Studies of cheliceral and deutosternal morphology of some Phytoseiidae (Acari: Mesostigmata) by scanning electron microscopy. Intl. J. Acarol., 18: 163-169. https://doi.org/10.1080/01647959208683947
7. Flechtmann C.H.W., Evans G.O., McMurtry J.A. 1994. Some noteworthy features of the chelicerae and subcapitulum of Phytoseiulus longipes Evans (Acari: Mesostigmata: Phytoseiidae), with observations on the preoral channel in the Phytoseiidae. Exp. App. Acarol., 18(5): 293-299. https://doi.org/10.1007/BF00132318
8. Kreiter S., Tixier M.S. 2006. A new genus and species of phytoseiid mites (Acari: Mesostigmata) from southern Tunisia, with discussion of its phylogenetic position. Zootaxa, 1237(1): 1-18. https://doi.org/10.11646/zootaxa.1237.1.1
9. Negm M.W., Alatawi F.J. 2013. First record of Otopheidomenidae Treat, 1955 (Acari: Mesostigmata) in Saudi Arabia, with description of Nabiseius arabicus sp. nov. Turk J Zool., 37(2): pp.184-187. https://doi.org/10.3906/zoo-1207-26
10. Rowell H.J., Chant D.A., Hansell R.I.C. 1978. The determination of setal homologies and setal patterns of the dorsal shield in the family Phytoseiidae (Acarina: Mesostigmata). The Can. Entomol., 110: 859-876. https://doi.org/10.4039/Ent110859-8

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