Introduction

The family Syringophilidae Lavoipierre, 1953 includes highly specialised parasites of birds. These mites live and reproduce inside the quills of various feather types (e.g. primaries, secondaries, coverts, rectrices and body feathers), feeding on the soft tissue fluids of their hosts by piercing the calamus wall with their long and flexible cheliceral digits (Kethley, 1971). The host-parasite relationships of syringophilids and their biodiversity are still poorly known. To date the family includes 269 species of 53 genera recorded from more than 180 bird species belonging to 69 families of 21 orders from all of the geographical regions, except for the Antarctic (Skoracki, 2011; Skoracki & OConnor, 2010; Skoracki et al., 2011, 2012). However, the actual number of syringophilid species is estimated to be at least 5,000 based on the species numbers of their potential hosts (Johnston & Kethley, 1973). In contrast to members of the subfamily Syringophilinae Lavoipierre, 1953, which mainly inhabit the flight feathers, most species of the subfamily Picobiinae Johnston & Kethley, 1973, except for species of Calamincola Casto, 1978, occupy quills of the body feathers. This difference is likely a result of a basal divergence at an early stage of syringophilid evolution (Skoracki et al., 2004).

The subfamily Picobiinae includes 36 species of five genera (excluding three species assigned as incertae sedis): these include Picobia Haller, 1878 with 19 species parasitising birds of the orders Passeriformes, Piciformes and Upupiformes; Rafapicobia Skoracki, 2011 with two species found on passerines; Neopicobia Skoracki, 2011 with 10 species found on Passeriformes, Columbiformes and Psittaciformes; Columbiphilus Kivganov & Sharafat, 1995 with four species, one known from a columbiform host and the remaining species from galliforms; and Calamincola Casto, 1977 with a single species described from a cuculiform host (Casto, 1977; Kivganov & Sharafat, 1995; Fain et al., 2000; Skoracki et al., 2004; Skoracki, 2011; Skoracki & Sikora, 2011; Sikora et al., 2011; Glowska & Skoracki, 2011; Glowska et al., 2011).

To date, only one picobiine species, Rafapicobia zinitra Skoracki, 2011, has been described from muscicapid hosts, i.e. Saxicola rubetra (Linnaeus) and Ficedula hypoleuca (Pallas). In this paper, we describe three new species of Picobia found on African flycatchers.

Materials and methods

The material used in the present study was collected from dry bird skins housed in the ornithological collection of the Bavarian State Collection of Zoology (ZSM), Munich, Germany. Mites were extracted with sharp, fine tweezers through a longitudinal cut made in the quill. Before mounting, mites were softened and cleared in 10% lactic acid at 60°C for 2–3 days. For light microscope studies, mites were mounted on slides in Faure’s medium and examined under an Olympus BH-2 light microscope with differential interference contrast (DIC) optics. Drawings were made with camera lucida. All measurements, including the figure scale-bars, are given in micrometres. The idiosomal setation follows Grandjean (1939), as adapted for the Prostigmata by Kethley (1990). The system of nomenclature for leg setation follows that proposed by Grandjean (1944), as adapted for the Syringophilidae by Bochkov et al. (2008) and Skoracki (2011). Bird taxonomy and nomenclature of birds follow Clements (2007). Specimen depositories and reference numbers are cited using the following abbreviations: AMU, A. Mickiewicz University, Natural History Collection, Poznan, Poland; ZSM, Bavarian State Collection of Zoology, Munich, Germany.

Family Syringophilidae Lavoipierre, 1953

Subfamily Picobiinae Johnston & Kethley, 1973

Genus Picobia Haller, 1878

Picobia cichladusa n. sp.

Type-host: Cichladusa arquata Peters (Passeriformes: Muscicapidae).

Type-locality: Tanzania, Soga, 16 July 1960, coll. Th. Andersen.

Type-material: Female holotype (non-physogastric form) and paratypes: 1 female (non-physogastric form), 2 females (physogastric form), 1 male, 2 nymphs. Mites removed by M. Skoracki. Host specimen deposited in the ZSM. All type-material is deposited in the ZSM (Reg. No. ZSM 20112002), except for 1 female paratype (physogastric form) in the AMU (Reg. No. AMU-SYR.371).

Etymology: The name of this species refers to the generic name of the host.

Description (Figs. 1–9)

Non-physogastric female (Figs. 1–5). [Based on holotype and 1 paratype.] Total body length 485 (555). Gnathosoma. Hypostomal apex rounded, without shoulders (Fig. 3). Infracapitulum apunctate. Movable cheliceral digit edentate posteriorly, 145 (145) long. Each medial branch of peritremes with 3–4 chambers; each lateral branch with 7 chambers (Fig. 4). Stylophore 185 (180) long. Podomers of palps densely punctate. Idiosoma. Propodonotal shield punctate, divided into 2 narrow lateral and single oval median shields. Length ratio of setae vi:ve:si is 1.3:1:1.3. Bases of setae vi and ve situated at same transverse level. Setae c1 located slightly anterior to level of setae se. Dorsal setae of idiosoma and legs lightly beaded (Fig. 5). Pygidial shield well developed, punctate. Setae f2 1.4 times longer than f1. Setae f1 1.4–1.5 times longer than h1. Aggenital setae ag1 situated anterior to level of setae ag2. Length ratio of setae ag1:ag2:ag3 1.3:1:2. Genital plate present, punctate. Genital lobes present. Pseudanal setae ps1 and ps2 subequal in length. Genital setae filiform, situated on genital lobes, subequal to pseudanal setae (Fig. 6). All coxal fields well sclerotised, apunctate. Setae 4c 1.3 times longer than 3c. Length ratios of setae 3b:3c and 4b:4c 1:2.3 and 1:3.2, respectively. Legs. Antaxial and paraxial members of claws subequal in size. Setae tc′ and tc″ of legs III–IV subequal in length. Lengths of setae: vi 115, ve 90 (90), si 115 (120), se 210 (180), c1 220 (215), c2 195 (180), d1 205 (180), d2 210 (195), e2 150 (155), f1 70 (65), f2 100 (95), h1 50, h2 >200, ag1 55 (60), ag2 40 (45), ag3 85 (90), g1 30 (30), ps1 30 (30), ps2 30 (30), tc′III–IV 50 (55), tc″III–IV 50 (55), l′RIII 30 (25), 3b (30), 3c 70 (65), 4b 30 (30), 4c 95 (95).

Figs. 1, 2
figure 1

Picobia cichladusa n. sp., female: 1, dorsal view; 2, ventral view

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Figs. 3–7
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Picobia cichladusa n. sp.: (3–6), female: 3, hypostomal apex; 4, peritremes; 5, propodonotal seta ve; 6, terminal opisthosoma in ventral view; (7), male: 7, peritremes

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Physogastric female. [Based on 1 paratype.] Body, vermiform in outline, 895 long. Other characters as in non-physogastric form.

Male (Figs. 7–9). [Based on 1 paratype.] Total body length 435. Gnathosoma. Hypostomal apex rounded. Infracapitulum apunctate. Stylophore 100 long. Each medial branch of peritremes with 3 chambers; each lateral branch with 7–8 chambers (Fig. 7). Idiosoma. Propodonotal shield divided into 2 narrow and sparsely punctate lateral shields and unpaired oval shield situated in middle of propodonotum. Length ratio of setae vi:ve:si are 1.3:1:1.3. Idiosomal setae vi, ve, si, se, c1, c2 and d2 slightly beaded; other idiosomal setae smooth. Bases of setae vi and ve situated at same transverse level. Setae c1 and se situated at same transverse level. Hysteronotal shield well developed, entire, apunctate, bearing bases of setae d1 and e2. Setae d2 about 9 times longer than d1 and e2. Pygidial shield well sclerotised, apunctate. Setae h2 about 15 times longer than f2. Two aggenital plates present, bearing bases of setae ag1 on posterior margin. Setae ag1 1.8 times longer than ag2. All coxal fields well sclerotised and apunctate. Setae 4c 1.4 times longer than 3c. Length ratios of setae 3b:3c and 4b:4c 1:2.3 and 1:2.6, respectively. Legs. Dorsal setae of all legs slightly beaded. Setae tc′ and tc″ of legs III–IV subequal in length. Lengths of setae: vi 100, ve 75, si 100, se 140, c1 165, c2 130, d1 15, d2 140, e2 15, f2 15, h2 >140, ag1 45, ag2 25, tc′III–IV and tc″III–IV 45, l′RIII 25, 3b 20, 3c 45, 4b 25, 4c 65.

Figs. 8, 9
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Picobia cichladusa n. sp., male: 8, dorsal view; 9, ventral view

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Differential diagnosis

Picobia cichladusa n. sp. is morphologically similar to P. currucae Skoracki & Magowski, 2001 described from Sylvia curruca (Linnaeus) (Passeriformes: Sylviidae) in Poland (Skoracki & Magowski, 2001). In females of both species: the hypostomal apex is rounded; the peritremes are M-shaped; the movable cheliceral digit is edentate posteriorly; the pygidial and genital shields are well developed; the genital setae are filiform and situated on well developed genital lobes; and the hysteronotal is absent. This new species differs from P. currucae by the following characters: in females of P. cichladusa, aggenital setae ag2 are situated posterior to the level of setae ag1; genital setae g1 and pseudanal setae ps1 and ps2 are subequal in length; the propodonotal shield is punctate and divided into two narrow lateral shields and a single oval median shield. Whereas, in females of P. currucae, aggenital setae ag1 and ag2 are situated at the same transverse level; genital setae g1 are 2–2.5 times longer than pseudanal setae ps1 and ps2; and the propodonotal shield is apunctate and divided only into two narrow lateral shields, i.e. the unpaired median shield is absent.

Picobia echo n. sp.

Type-host: Cossypha heuglini Hartlaub (Passeriformes: Muscicapidae).

Type-locality: D. R. Congo, South Kivu Prov., Bukavu, 7 August 1969, coll. P. Kunkel.

Type-material: Female holotype (non-physogastric form) and paratypes: 4 females (physogastric form), 2 males, 2 nymphs and 1 larva. Host specimen is deposited in the ZSM. Mites removed by M. Skoracki. All material is deposited in the ZSM (Reg. No. ZSM 20112010), except 1 female paratype (physogastric form) in the AMU (Reg. No. AMU-SYR.372).

Etymology: The name of this species derives from the Greek εχώ (ēchō), “sound”.

Description (Figs. 10–21)

Non-physogastric female (Figs. 10–16). [Based on holotype.] Total body length 565. Gnathosoma. Hypostomal apex rounded, without shoulders (Fig. 12). Infracapitulum apunctate. Movable cheliceral digit edentate posteriorly, 145 long. Each medial branch of peritremes with 4–5 chambers; each lateral branch with 6–8 chambers (Fig. 13). Stylophore 185 long. Podomers of palps densely punctate. Idiosoma. Propodonotal shield punctate, divided into 2 narrow lateral and single oval median shields. Length ratio of setae vi:ve:si is 1:1:1.4. Bases of setae vi and ve situated at same transverse level. Setae c1 set slightly anterior to level of setae se. Dorsal setae of idiosoma (except terminal setae h2) lightly beaded. Pygidial shield well developed, punctate. Setae f2 twice as long as f1. Setae f1 and h1 subequal in length. Aggenital setae ag1 situated anterior to level of setae ag2. Length ratio of setae ag1:ag2:ag3 1.4:1:2. Genital plate present, punctate. Genital lobes present. Pseudanal setae ps1 1.4 times longer than ps2. Genital setae filiform, situated on genital lobes (Fig. 15). All coxal fields well sclerotised, apunctate. Setae 4c not significant (1.1–1.2 times) longer than 3c. Length ratios of setae 3b:3c and 4b:4c 1:2.4. Legs. Antaxial and paraxial members of claws subequal in size (Fig. 16). Setae tc′ and tc″ of legs III–IV subequal in length. Dorsal setae of all legs lightly beaded. Lengths of setae: vi 125, ve 125, si 180, se 215, c1 240, c2 205, d1 190, d2 220, e2 185, f1 45, f2 90, h1 45, h2 >200, ag1 65, ag2 45, ag3 90, g1 20, ps1 35, ps2 25, tc′III–IV 60, tc″III–IV 60, l′RIII 35, 3b 35, 3c 85, 4b 40, 4c 95.

Figs. 10, 11
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Picobia echo n. sp., female: 10, dorsal view; 11, ventral view

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Figs. 12–19
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Picobia echo n. sp.: (12–16) female: 12, hypostomal apex; 13, peritremes; 14, solenidia of leg I; 15, terminal opisthosoma in ventral view; 16, tarsus III in ventral view; (17–19) male: 17, hypostomal apex; 18, peritremes; 19, genito-anal region

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Physogastric female. [Based on 1 paratype.] Body, vermiform outline, 1,100 long. Other characters as in non-physogastric form.

Male (Figs. 17–21). [Based on 2 paratypes.] Total body length 380–410. Gnathosoma. Hypostomal apex rounded (Fig. 17). Infracapitulum apunctate. Stylophore 105 long. Each medial branch of peritremes with 3–4 chambers; each lateral branch with 7–8 chambers (Fig. 18). Idiosoma. Propodonotal shield punctate, divided into 2 narrow lateral shields and one unpaired oval shield situated in middle of propodonotum. Length ratio of setae vi:ve:si 1:1:1.1–1.2. Idiosomal setae vi, ve, si, se, c1, c2 and d2 slightly beaded; other setae smooth. Bases of setae vi and ve situated at same transverse level. Setae c1 situated slightly anterior to level of setae se. Hysteronotal shield well developed, entire, apunctate, bearing bases of setae d1 and e2. Setae d2 about 7 times longer than d1 and e2. Pygidial shield well sclerotised, apunctate. Setae h2 about 13 times longer than f2. Two aggenital plates present, situated close to each other, bearing bases of setae ag1. Setae ag1 1.3–1.8 times longer than ag2. All coxal fields well sclerotised and apunctate. Setae 4c not significant (1.1–1.2 times) longer than 3c. Legs. Dorsal setae of all legs slightly beaded. Setae tc′ and tc″ of legs III–IV subequal in length. Lengths of setae: vi 105, ve 100–115, si 100–125, se 155–160, c1 165, c2 150–160, d1 20, d2 140, e2 20, f2 15, h2 160–190, ag1 45, ag2 25–35, tc′III–IV and tc″III–IV 50–55, l′RIII 25, 3b 25, 3c 50, 4b 25, 4c 55–60.

Figs. 20–21
figure 6

Picobia echo n. sp., male: 20, dorsal view; 21, propodosoma and opisthosoma in ventral view

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Differential diagnosis

This species is morphologically similar to P. cichladusa n. sp., described above, and is distinguished by the following characters: in females of P. cichladusa, setae vi are longer than ve (1.3 times); setae si and vi are subequal in length; the length ratio of setae f1:f2 is 1:1.4; and the lengths of setae se, e2 and f1 are 115–120, 150–155 and 60–70 μm, respectively. In females of P. echo n. sp., setae vi and ve are subequal in length; setae si are 1.4 times longer than vi; the length ratio of setae f1:f2 is 1:2; and the lengths of setae se, e2 and f1 are 180, 185 and 45 μm, respectively.

Picobia myrmecocichla n. sp.

Type-host: Myrmecocichla arnotti (Tristram) (Passeriformes: Muscicapidae).

Type-locality: Tanzania, 10 September 1963, coll. Th. Andersen.

Type-material: Female holotype (non-physogastric form) and paratypes: 1 female (non-physogastric form), 2 females (physogastric form), 2 males, 1 nymph. Mites removed by M. Skoracki. Host specimen is deposited in the ZSM. All material is deposited in the ZSM (Reg. No. ZSM 20112011), except 1 female paratype (physogastric form) in the AMU (Reg. No. AMU-SYR.375).

Etymology: The name of this species refers to the generic name of the host.

Description (Figs. 22–32)

Non-physogastric female (Figs. 22–27). [Based on holotype and 1 paratype.] Total body length 530 (520). Gnathosoma. Hypostomal apex rounded, without shoulders (Fig. 24). Infracapitulum apunctate. Movable cheliceral digit edentate posteriorly, 160 (160) long. Each medial branch of peritremes with 5–6 chambers; each lateral branch with 7 chambers (Fig. 26). Stylophore 200 (195) long. Podomers of palps densely punctate. Idiosoma. Propodonotal shield divided into 2 narrow and punctate lateral shields; median shield reduced to small sclerite or absent. Length ratio of setae vi:ve:si is 1.4–1.6:1:1.4–1.6. Bases of setae vi situated slightly posterior to level of setae ve. Setae c1 located anterior to level of setae se. Dorsal setae of idiosoma and legs lightly beaded. Pygidial shield well developed, punctate. Setae f2 2–2.3 times longer than f1. Setae f1 and h1 subequal in length. Aggenital setae ag1 situated anterior to level of setae ag2. Length ratio of setae ag1:ag2:ag3 2:1:2.7. Genital plate punctate. Genital lobes present. Pseudanal setae ps1 and ps2 subequal in length. Genital setae filiform, situated on genital lobes. All coxal fields well sclerotised, apunctate. Setae 4c slightly (1.1–1.2 times) longer than 3c. Length ratios of setae 3b:3c 1:2.5–2.7. Legs. Antaxial and paraxial members of claws subequal in size. Setae tc′ and tc″ of legs III–IV subequal in length. Lengths of setae: vi 110 (125), ve 80 (80), si 110 (125), se 215 (220), c1 235 (215), c2 (205), d2 225 (225), e2 145 (140), f1 35 (30), f2 70 (70), h1 35 (30), h2 >200, ag1 55 (60), ag2 (30), ag3 75 (80), g1 25, ps1 (30), ps2 25, tc′III–IV 55 (55), tc″III–IV 55 (55), l′RIII 30 (25), 3b 30 (30), 3c 75 (80), 4c 90 (90).

Figs. 22, 23
figure 7

Picobia myrmecocichla n. sp., female: 22, dorsal view; 23, ventral view

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Figs. 24–30
figure 8

Picobia myrmecocichla n. sp.: (24–27) female: 24, hypostomal apex; 25, solenidia of leg I; 26, peritremes; 27, terminal opisthosoma in ventral view; (28–30) male: 28, hypostomal apex; 29, peritremes; 30, genito-anal region

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Physogastric female. [Based on 1 paratype.] Body, vermiform outline, 1,050 long. Other characters, excluding pygidial shield clearly punctate, as in non-physogastric form.

Male (Figs. 28–32). [Based on 2 paratypes.] Total body length 435. Gnathosoma. Hypostomal apex rounded (Fig. 28). Infracapitulum apunctate. Stylophore 95–105 long. Each medial branch of peritremes with 3 chambers; each lateral branch with 7–8 chambers (Fig. 29). Idiosoma. Propodonotal shield not divided, long-sleeved shirt-like, punctate near bases of setae ve and si. Length ratio of setae vi:ve:si are 1.2–1.3:1:1.4–1.5. Idiosomal setae vi, ve, si, se, c1, c2 and d2 slightly beaded; other setae smooth. Bases of setae vi situated slightly posterior to level of setae ve. Setae c1 situated anterior to level of setae. Hysteronotal shield well developed, trapezoidal in shape, apunctate, bearing bases of setae d1 and e2. Setae d2 8–10 times longer than d1 and e2. Pygidial shield well sclerotised, apunctate. Setae h2 about 15 times longer than f2. Two aggenital plates present, weakly developed; bases of setae ag1 situated near these plates. Setae ag1 and ag2 subequal in length. All coxal fields well sclerotised and apunctate. Length ratio of setae 3b:4b:3c:4c 1:1:2.3:2–2.3. Legs. Dorsal setae of all legs lightly beaded. Setae tc′ and tc″ of legs III–IV subequal in length. Lengths of setae: vi 70, ve 55–60, si 80–85, se 140, c1 135, c2 130, d1 15–20, d2 120, e2 15–20, f2 10, h2 150, ag1 30, ag2 25–30, tc′III–IV and tc″III–IV 40–45, l′RIII 25, 3b 20, 3c 45, 4b 20, 4c 40.

Figs. 31, 32
figure 9

Picobia myrmecocichla n. sp., male: 31, dorsal view; 32, ventral view

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Differential diagnosis

This new species is morphologically similar to P. cichladusa n. sp., described above by the presence of setae vi and si which are subequal in length in the females. It differs from P. cichladusa as follows: in females of P. myrmecocichla n. sp., the propodonotal median shield is reduced or absent; the lengths of setae f1 and f2 are 30–35 and 70 μm, respectively; the length ratio of setae ag1:ag2:ag3 is 2:1:2.7; and setae f1 and h1 are subequal in length; in males, the propodonotal shield is not divided; the aggenital plates are strongly reduced and setae ag1 are situated near these plates; and setae vi are 70 μm long. In females of P. cichladusa, the propodonotal median shield is well sclerotised; the lengths of setae f1 and f2 are 60–70 and 95–100 μm, respectively; the length ratio of setae ag1:ag2:ag3 is 1.3:1:2; and setae f1 are 1.4–1.5 times longer than h1; in males, the propodonotal shield is divided into three sclerites; the aggenital plates are well developed and the bases of setae ag1 are situated on these plates; and setae vi are 100 μm long.