Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov., 2024

Kohansal, Mahnaz, Noei, Javad, Ramroodi, Sara & Rakhshani, Ehsan, 2024, Description of Neosilphitrombium rhipicephalum sp. nov. (Prostigmata: Neothrombiidae) ectoparasite on hard ticks from Iran, Zootaxa 5481 (3), pp. 326-340 : 327-335

Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov.

( Figs. 1–12 )

Diagnosis of larva: Leg segmentation formula, 6-6-6; Scutum approximately square-shaped; scutellum with seven normal setae; AL setae bilobed, AM and PL barbed; fn Cx = 3-4-2; fn Tr = 1-1-1; fn Fe = 6-4-4; fn Ge = 4-2-2; fn Ti = 6-5-5; fn Ta = 18-13-13; fSol = I (0-2-2-1), II (0-1-2-1), III (0-1-0-0); fκ = I (1-1), II (0-0), III (0-0); fζ = 2-0-0; fε = 1-1-0; fPp = 0-0-0-BNN 2 -BBBNωζ; IP = 669.

Description of larva (n = 1)

Dorsum ( Figs. 1–4 ). Dorsal surface with 41 barbed setae, scutum with one pair of sensilla (S) and three pairs of normal setae (AM, AL and PL). AM and PL setae barbed, AL bilobed. Sensillary setae (S) broken and posteromedially to PL setae. Scutum approximately square-shaped, punctate, with two spots posterolaterally on each side of AL setae. Two eyes placed posterolaterally on each side of scutum on punctate ocular sclerite (25×12); anterior lens (diameter 8) slightly larger than posterior one (diameter 6). Scutellum punctate, approximately rectangular-shape, anterior border deeply concave, lateral and posterior borders straight, and with seven barbed setae.

Venter ( Figs. 5 , 11–12 ). Ventral surface of idiosoma with 36 barbed setae behind coxae III, a uropore and one pair of barbed sternal setae, 3a. NDV= 41 + 36 = 77. Coxae I–III punctate. Coxa I with three bilobed setae (1b 1, 1b 2, 1b 3), supracoxal seta (elc I) present, 4 long; coxa II with four setae including three bilobed setae (2b 1, 2b 2, 2b 3) and one barbed seta (2b 4); coxa III with two bilobed setae (3b 1, 3b 2). Claparède’s organs on coxae I circular.

Gnathosoma ( Figs. 6–7 ). Cheliceral bases 50 long, punctate on dorsal surface; cheliceral blade 16 long, curved with one subterminal tooth. Subcapitulum with nude galeala (cs) and bilobed ssubcapitular seta (bs). Palp femur 16 and palp genu 7 long, each without seta; palp tibia 10 long with two nude and one barbed setae; palp tarsus 4 long, with three barbed and one nude seta (two barbed setae longer than others), a solenidion and an eupathidium. Palp tibial claw 9 long, bifurcate with equal branches. Supracoxal seta absent. fPp = 0-0-0-BNN 2 -BBBNωζ.

Legs ( Figs. 8–12 ). Leg segmentation formula: 6-6-6. Leg setal formula: Leg I: Ta 1ω, 1ɛ, 2ζ, 18n; Ti 2φ, 1κ, 6n; Ge 2σ, 1κ, 4n; Fe 6n; Tr 1n; Cx 3n ( Figs. 8 , 11 ); Leg II: Ta 1ω, 1ɛ, 13n; Ti 2φ, 5n; Ge 1σ, 2n; Fe 4n; Tr 1n; Cx 4n ( Figs. 9 , 11 ); Leg III: Ta 13n; Ti 5n; Ge 1σ, 2n; Fe 4n; Tr 1n; Cx 2n ( Figs. 10, 12 ). Tarsal claws 3-3-3. Measurements are given in Table 1 . Etymology: The specific epithet is derived from the genus name of the tick host, Rhipicephalus sanguineus .

Type material: The holotype (ARS-20210131-3a) was collected ectoparasitic on a R. sanguineus ( Acari : Ixodida : Ixodidae ), IRAN: South Khorasan province, Sarbisheh county, Doroh village, 32° 11.29’ N, 60° 28.75’ E, 1375 m a.s.l., 3 July 2020, coll. Mahnaz Kohansal.

Type deposition. The holotype larva is deposited in the Acarological Collection , Jalal Afshar Zoological Museum , Department of Plant Protection , Faculty of Agriculture , University of Tehran, Karaj, Iran .

Remarks and discussion

Based on Kohansal et al. (2021), the family Ixodidae ( Acari : Parasitiformes: Ixodida ) has been recorded for the first time as host for larval neothrombiids. This host association is new for the taxon and is very rare cases of ectoparasitism on tarsi. Several attempts were made to gather additional specimens through samplings, but none were successful. The distinct differences to the other species justify its description as a new species. Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov. clearly belongs to the family Neothrombiidae based on Noei (2020: 932) and the genus Neosilphitrombium based on the identification key in the present paper. Three genera including Neosilphitrombium , Silphitrombium and Vagatotrombium have bilobed setae on Cx I–III only. The genus Neosilphitrombium is distinguished from Silphitrombium and Vagatotrombium by having two (previous described species) or more (present study) barbed setae on scutellum (vs. with two bilobed setae on scutellum in Silphitrombium and Vagatotrombium ) and two bilobed setae (AL) on scutum (vs. with four bilobed setae (AL, PL) on scutum). Presence of more than two barbed setae on scutellum in the new species unlike the previous described species, is interpreted as intraspecific variation. Therefore, the generic diagnosis of Neosilphitrombium and key to world genera of Neothrombiidae are amended. The members of Neosilphitrombium were recorded from Palaearctic region, including three species, only based on larva ( Mąkol & Wohltmann 2012) as follows: N. gratum Fain, 1992 , N. annabellae Haitlinger, 2001 from Belgium (Europe) and India (Asia) respectively, both ectoparasitic on undetermined carrion beetles ( Coleoptera : Silphidae ) and N. tenebrionidum Saboori, Hajiqanbar and Hakimitabar, 2011 from Iran (Asia) ectoparasitic on Opatroides punctatus Brullé ( Coleoptera : Tenebrionidae ) ( Fain 1992a; Haitlinger 2001; Saboori et al. 2011; Felska et al. 2018). Presence of more than two barbed setae on scutellum and shape of scutum differentiate the new species from all other species of genus hitherto known. Therefore, the new species differs from all species of the genus in the number of setae on scutellum (7 vs. 2 in other species) and in the shape of scutum (square-shaped vs. oval or of different shape). Based on Saboori et al. (2011: 68), the number of normal setae on legs in the members of Neosilphitrombium is typically constant, but they used the variation of normal setae in identification key. Therefore, the identification key of larval species was changed. The metric data of N. tenebrionidum and N. gratum of Saboori et al. (2011) were missed in paper publishing process and are presented in this paper ( Tables 2 and 3 ).

Figures

FIGURE 1. Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov. (larva)—Dorsal view of idiosoma, the scutum and left ocular sclerite have rotated upward.

FIGURE 2. Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov. (larva), Propodosoma, the scutum and left ocular sclerite have rotated.

FIGURE 3–4. Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov. (larva), 3. Scutum; 4. Scutellum.

FIGURE 5. Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov. (larva), Ventral view of idiosoma.

FIGURES 6–7. Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov. (larva), 6. Dorsal view (right) and ventral view of gnathosoma (left); 7. Ventral view of palpal tarsus.

FIGURES 8–9. Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov. (larva), Leg I: 8. Tr–Ta; Leg II: 9. Tr–Ta.

FIGURES 10–12. Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov. (larva), Leg III: 10. Tr–Ta; Leg I–III: 11. Cx I–II 12. Cx III.

Tables

TABLE 1. Metric data of Neosilphitrombium rhipicephalum Noei and Kohansal sp. nov. (larva).

Character	Holotype	Character	Holotype
IL	~530	2b 4	15
IW	~600	3a	22
SD	91	3b 1	5
W	85	3b 2	6
AW	27	cs	8
PW	70	bs	9
AA	35	Cx I	62
SB	55	Tr I	30
ASB	63	Fe I	35
PSB	28	Ge I	25
MA	10	Ti I	27
AP	43/47	Ta I (L)	47
AL	5	Ta I (H)	16
PL	36	Leg I	226
AM	30	Cx II	57
S	> 22	Tr II	27
LN	5	Fe II	30
MSA	12	Ge II	22
SA	52	Ti II	25
SP	10	Ta II (L)	45
LSS	90	Ta II (H)	15
HS	32	Leg II	206
SL	42–45	Cx III	55
DS min.	27	Tr III	35
DS max.	45	Fe III	38
GL	68	Ge III	22
1b 1	5	Ti III	32
1b 2	5	Ta III (L)	55
1b 3	8	Ta III (H)	12
2b 1	5	Leg III	237
2b 2	5	IP	669
2b 3	5