Vulgarogamasus sphecophilus Cooreman, comb. nov.
Creators: name: Baker, Anne S.
name: Foster, Kevin R.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Mesostigmata
Parasitidae
Vulgarogamasus
Vulgarogamasus sphecophilus

description: Vulgarogamasus sphecophilus (Cooreman) comb. nov.
(Figs 1–38)
Eugamasus sphecophilus Cooreman, 1945: 221.
Poecilochirus britannicus Hyatt, 1986: 17. New synonymy.
Material examined. Eugamasus sphecophilus: Paratype female (slide M83, whole specimen) and male (slide M82, idiosoma, gnathosoma, legs I, III–IV), BELGIUM, Braine-l’Alleud, from nest of Ve s p a silvestris Scopoli [= Dolichovespula sylvestris] (Hymenoptera: Vespidae), coll. A. Crèvecoeur, 7.VIII.1945. Other specimens: females (slides M66 (gnathosoma); M81, 68 (idiosoma and legs)); males (slides M70, 74, 76 (legs II); M75, 79 (gnathosoma); M67, 73, 80 (idiosoma, gnathosoma, legs I, III–IV)); male deutonymph (slides M69 (gnathosoma and legs I); M71 (idiosoma and legs II–IV); M77 (whole specimen)), same data as type material [all deposited in the Department of Entomology, Royal Belgian Institute of Natural Sciences, Brussels].
Poecilochirus britannicus: Holotype female, 2 paratype females, 2 paratype males, ENGLAND, South Yorkshire, Rotherham, from a nest of Dolichovespula silvestris (Scopoli) [incorrect spelling of D. sylvestris] (Hymenoptera: Vespidae) in a bird nest-box, coll. A.J. Bickerstaffe, 1.VIII.1982 [deposited in the Natural History Museum, London; BMNH 1985.5.15.1–5].
Vulgarogamasus sphecophilus comb. nov.: 5 females, 5 males, 10 deutonymphs, ENGLAND, ex. nests of Dolichovespula saxonica (Fabricius) (Hymenoptera: Vespidae), coll. K.R. Foster [deposited in the Natural History Museum, London; BMNH 2009(E)-38]; other voucher specimens deposited in the second author’s personal collection.
Diagnosis. The form of the gnathotectum distinguishes adults and deutonymphs of this species from those of the other members of the genus. It is approximately triangular in shape and has a variable number of irregularly-sized and arranged serrations. In females, it is usually accuminate, sometimes approximately truncate or rounded, and with numerous serrations. In males, it is truncate–rounded with none to a few serrations, usually located apically. In deutonymphs, it has an acuminate–truncate apex, numerous serrations and a submarginal arc of faint striae.
FEMALE (mean (range), n=11; measurements of individual specimens given in Table 1).
Idiosomal shields and legs moderately to well-sclerotized; shields reticulated and minutely punctate, gnathosoma and legs minutely punctate. Setae mostly weakly–moderately pilose in distal half, pilosity of some only visible at high magnifications; sometimes one or both members of a setal pair is absent or additional unpaired setae are present.
Idiosoma - dorsum (Figs 1, 3, 4). Podonotal shield: 539(467–595) long, 800(704–864) wide (between posterolateral angles); bears 23 pairs of setae; j1 located on marginal band of punctate and faintly reticulated cuticle extending between peritrematic shields and to poroids id1; z1 very short, the most slender pair; s1 and s2 also more slender than remaining setae, s1 shorter than s2; r3 the longest; j4 and z5 noticeably short, the latter pair spiniform; j5, j6 and z6 very variable in length, variation sometimes disproportionate to body length, short form spiniform, longer ones like adjacent setae; remaining setae reach or just overlap base of one posterior. Opisthonotal shield: 590(541–640) long, 882(762–944) wide (between anterolateral angles), posterior margin with slight median convexity; bears 28 pairs of setae; setae in J and Z rows and some in S row spiniform, distinctly shorter than other setae, particularly those in anterolateral regions, disproportionate variation in length recorded in most pairs. Setal lengths - j1 77(72–86), j2 95(70–110), j3 93(78–105), j4 50(43–54), j5 72(60–96), j6 51(32–86), z1 32(26–37), z2 94(80–102), z3 93(78–107), z4 82(67–94), z5 47(38–58), z6 51(32–90), s1 60 (43–77), s2 74 (53–90), s3 102(88–109), s4 90 (78–101), s5 107(93–117), s6 76 (54–97), r2 83(66–94), r3 110(98–123), r4 86(74–110), r5 91(77–105), r6 103(88–112), J1 49(29–88), J2 42(30–83), Z1 53(30–91), S1 70 (47–97), R1 86(64–99); eight pairs of setae on integument surrounding shield, c. 40–70 long. Pore-like structures: podonotal shield with nine pairs, hypothesized as poroids id1, 2, 4–6 and gland pores gd1, 2, 4, 5; opisthosomal shield with 13, including those hypothesized as idm1–4, 6, idx, idl1, isl1 and gd6. Peritremes extend anteriorly to between level of j2 and z1.
Character E. sphecophilus P. britannicus British, ex. D. saxonica
M68, 81, 83 holotype, paratypes
Podonotal shield length 573, 538, 531 525, 544, 595 573, 467, 522, 506, 554
Podonotal shield width 857, 736, 704 864, 848, 864 858, 704, 816, 728, 821
Opisthonotal shield length 621, 570, 573 614, 640, – 636, 550, 566, 541, 586
Opisthonotal shield width 936, 800, 762 936, 920, 944 940, 768, 902, –, 908
Idiosomal setal lengths
j1 85, 73, 74 –, –, 81 74, 67, 77, 72, 86
j2 110, 101, – 105, 99, 101 97, 70, 101, 91, 78
j3 99, 83, 85 105, 101, – 102, 78, 94, 82, 102
j4 –, 51, 45 53, –, – 54, 43, 50, 48, 54
j5 70, 60, 65 85, –, – 96, 61, 72, 61, 82
j6 45, 32, 35 69, 70, 46 87, 34, 45, 34, 64
z 1 33, 28, – –, –, 32 34, 26, 37, 30, 37
z2 98, 91, 94 99, –, – 102, 80, 96, 85, 101
z3 101, 91, 88 107, –, – 99, 78, 100, 83, –
z4 83, 74, 78 93, 87, – 94, 67, 81, 69, 90
z5 58, 38, 45 52, 46, – 56, 38, 44, 43, 51
z6 38, 33, 34 69, 69, 54 90, 37, 46, 32, 64
s1 59, 43, – –, 61, 74 77, 48, 62, 46, 69
s2 85, 53, – –, –, 86 90, 54, 80, 61, 82
s3 109, 99, – 106, 101, 109 102, 88, 104, 93, 106
s4 95, 83, 81 99, 101, – 94, 78, 88, 83, 96
s5 115, 102, 98 117, 109, 111 109, 93, 112, 98, 112
s6 83, 58, 55 94, 91, 76 97, 59, 78, 54, 90
r2 94, 84, 74 –, 83, 93 88, 66, 82, 71, 92
r3 123, 115, 113 115, 106, 111 104, 98, 115, 101, 112
r4 100, 81, 78 110, 96, 104 102, 74, 102, 104
r5 99, 77, 78 101, 94, 101 91, 77, 96, 86, 105
r6 107, 99, 96 110, 101, 107 106, 88, 110, 96, 112
J1 39, 32, 29 66, 64, 46 88, 32, 48, 35, 64
J2 –, 30, 32 45, 51, 35 83, 30, 36, 32, 50
Z1 42, 32, 30 73, 65, 57 91, 37, 46, 35, 74
S1 59, 53, 50 –, 85, 96 97, 61, 67, 47, 86
R1 97, 72, 64 96, 91, 93 93, 67, 96, 80, 99
to be continued.
Idiosoma - venter (Figs 2, 5–7). Tritosternum: base longer than wide, accounts for c. 0.3 of total tritosternal length, with two pilose laciniae. Presternal shields not seen. Sternal shield: reticulations very faint or absent around apex of indentation between metapodal shields; setae st1 located on area of lighter sclerotization extending to poroid iv1; st2 slightly thicker than other sternal setae; lengths – st1 78(70–86), st2 77(68–86), st3 77(72–83); poroids iv1 and iv2 located just posterior to st1 and st2 respectively. Metasternal shields: anterior margin weakly defined; poroid iv3 located near anterior margin c. midway between seta st4 and median margin of shield; st4 79(73–86) long. Genital shield: 219(213–227) long; anterior margin with short median point; reticulations very faint or absent apically; with pair of anterolateral circular structures on internal surface; genital seta st5 60(46–67) long. Endogynium: comprises approximately pentagonal basal vaginal duct and oval, reticulated spherular organ, 36(31–42) long. Opisthogastric shield: narrows posteriorly, more strongly so just behind anus; with 9 pairs setae between anus and coxae IV (one or two unpaired accessory setae sometimes present, positions vary), more slender than dorsal setae, c. 32–53 long, ZV1 and SZ2 normally the shortest and slightly finer than other setae; paranal setae 30(29–32) long, located near posterior margin of anus; postanal seta 54(48–59) long, thicker and more strongly pilose than paranals; four pairs of pore-like structures, two close together on margin posterior to coxae IV, one posterolateral to st5, one lateral to setae ZV2. Integument surrounding shield bears four setal pairs, three of similar form and length to those on shield, plus the longer and thicker JV5, 70(62–77) long.
Gnathosoma (Figs 8–15). Gnathotectum: approximately triangular, irregularly and weakly serrated, anterior margin usually accuminate, sometimes more truncate (variations shown in Figs 9–14). Hypostome and basis gnathosomatica: 10 rows of multiple, minute hypognathal denticles; setal lengths - anterior hypostomatic 52(48–60), external posterior hypostomatic 38(32–40), internal posterior hypostomatic 68(64–77), palpcoxal 58(53–65). Palp: anterolateral femoral seta al spatulate distally with a few lateral tines; al1 and al2 of genu spatulate. Chelicera: fixed digit 62(58–65) long, with five subterminal teeth, basal retrorse tooth the largest, the two distal to the pilus dentilis very small, pilus dentilis slightly inflated basally then tapers to point; movable digit 80(73–83) long, with three retrorse subterminal teeth, proximal the largest, the others subequal, terminal tooth with a minute subapical denticle; dorsal seta smooth, blunt; lateral lyrifissure present; arthrodial membrane drawn out into setiform processes.
Legs (Fig. 16). Leg I thinnest, II thickest. Chaetotaxy: typical for family (sensu Evans 1963), from leg I–IV - coxa 2-2-2-1, trochanter 1-1/3-1, 1-0/3-1, 1-1/3-0, 1-1/3-0, femur 2-3+2/4-2, 2-3+2/3-1, 1-2+2/1-0, 1- 2+1/1-1, genu 2-3/2-3/1-2, 2-3/1-2/1-2, 2-2/1-2/1-1, 2-2/1-3/1-1, tibia 2-3/2-3/2-2, 2-2/1-2/1-2, 2-1/1-2/1-1, 2-1/1-3/1-2, tarsus II–IV 3-3 /2-1/1-3/2-3; femoral setae al2 of I, al2, ad2 and ad3 of II (as in Fig. 26), pd1 and pd2 of III and IV fine and much shorter than other setae; tarsus I with noticeably long mediodorsal seta; tarsi II–IV with setae ad1 and pd1 weakly lanceolate, c. subequal to or slightly longer than ambulacrum, al1, pl1, av1 and pv1 spiniform, shorter than other tarsal setae, av1 and pv1 thickened, all four setae thicker on tarsus II than on other tarsi.
MALE (mean(range), n=11; measurements of individual specimens given in Table 2).
Idiosoma - dorsum (Fig. 17). Dorsal shield: 1037(877–1176) long, 722(608–812) (at level of transverse suture); suture extends across most of width; c. 35 pairs opisthonotal setae; setal lengths - j1 80(67–93), j2 100(85–110), j3 94(75–109), j4 48(40–58), j5 57(33–91), j6 32(20–51), z1 39(32–48), z2 94(68–112), z3 101(85–114), z4 80(45–98), z5 39(32–48), z6 31(22–51), s1 64 (51–73), s2 77 (59–96), s3 103(85–115), s4 89 (58–107), s5 111(94–122), s6 59 (30–86), r2 87(70–98), r3 116(96–123), r4 100(79–112), r5 104(86–118), r6 106(83–123), J1 30(20–45), J2 23(20–27), Z1 29(21–42), S1 61 (28–102), R1 92(48–106).
Idiosoma - venter (Fig. 18). Tritosternum: base accounts for 0.13–0.17 of total length. Holoventral shield: poroids iv1, iv2 and iv3 respectively located just posterior to st1, approximately midway between st2 and st3, and anterior to st4; setal lengths – st1 63(57–66), st2 61(56–66), st3 54(50–59), st4 59(54–64), st5 52(46–58); opisthogastric element with 10 pairs of setae between anus and coxae IV (one or two unpaired setae sometimes present), c. 25–45 long; paranal setae 33(30–37) long, postanal 54(42–64), JV5 83(64–94); five pairs of pore-like structures, two pairs posterior to coxae IV more widely spaced than in female, one marginal pair just anterior to anterior margin of anus.
Gnathosoma (Figs 19–25). Gnathotectum: truncate–rounded, if serrations present, usually located along terminal margin, occasionally laterally, a central panel sometimes demarcated (variations shown in Figs 20–24). Hypostome and basis gnathosomatica: setae more weakly pilose than in female, each anterior seta mounted on short tubercle, setal lengths - anterior hypostomatic 48(40–54), external posterior hypostomatic 28(26–30), internal posterior hypostomatic 52(48–54), palpcoxal 44(42–48). Chelicera: fixed digit 89(81–97) long, blunt and weakly striated distally, one retrorse tooth just proximal to pilus dentilis; movable digit 92(80–101) long, ends proximally to tip of fixed digit, with one retrorse subterminal tooth c. midway along cutting edge, spermatodactyl not strongly elbowed.
Legs (Fig. 26). Leg II: markedly thicker than other legs; femur with large thumb- and small mushroomshaped apophyses; apophysis on genu and tibia small, rounded; all apophyses striated distally. Setae: al1 and pl1 on tarsus II not noticeably thicker than those on other tarsi; av2 thicker than other subterminal setae.
DEUTONYMPH (measurements: Eugamasus sphecophilus M71, 77 (for idiosoma) or M69, 77 (for gnathosoma), mean (range) of UK specimens [n=10]).
Idiosoma - dorsum (Figs 27, 32). Podonotal shield: 339, 355, 330(307–365) long, 397, 413, 375(333–429) wide (between posterolateral angles); bears 20 pairs of setae. Opisthonotal shield: rounded triangular, anterior margin with slight median extension, which is itself sometimes weakly concave; 224, 234, 217(208–240) long, 339, 346, 317(291–347) wide (between anterolateral angles); bears 13 pairs of setae (an unpaired seta sometimes present), eight of poroids and two of gland pores. Setae: short, spiniform, most less than half distance to seta posterior, r3 clearly the longest and thickest; r2 and r3 located on small punctate flange; lengths without wide variation - j 1 20, 19, 18(14–24), j2 –, 24, 22(20–27), j 3 28, 30, 27(25–30), j 4 12, 11, 12(11–13), j 5 26, 24, 25(22–26), j 6 19, 19, 19(18–22), z1 –, –, 13(11–16), z2 –, 24, 23(21–26), z3 –, 25, 22(19–26), z 4 27, 26, 25(22–30), z 5 13, 13, 13(11–16), z 6 18, 17, 18(16–20), s1 –, –, 14(11–16), s 2 15, 13, 14(13–16), s 3 27, 27, 26(24–29), s 4 30, 29, 27(25–32), s 5 22, 21, 21(19–24), s 6 21, 22, 22(21–26), r2 –, –, 14(12–16), r3 80, 79, 85(82–91), r 4 16, 14, 15(13–16), r 5 24, 24, 25(23–31), J 1 18, 18, 19(16–22), J 2 18, 16, 18(16–19), J 3 17, 15, 16(14–19), J 4 16, 14, 15(13–18), J 5 15, 13, 14(13–16), Z 1 19, 18, 19(16–21), Z 2 18, 16, 17(16–18), Z 3 17, 16, 15(13–17), Z 4 16, 14, 14(11–16), S 1 16, 13, 15(11–16), S 2 19, 18, 18(14–20), S 3 16, 16, 15(14–18), S 4 15, 15, 15(13–17). Integument surrounding opisthonotal shield with approximately 14 pairs of setae, c. 9–16 long, and three pairs of poroids.
Idiosoma - venter (Figs 28–31, 33). Tritosternum: base accounts for c. 0.35–0.40 of total length. Intercoxal region: pair of narrow, weakly sclerotized sclerites present just anterior to coxae II, second minute pair between coxae II and III. Sternal shield: 212, 213, 203(195–214) long, 149, 147, 143(134–147) wide (at level just anterior to poroid iv1); reticulate ornamentation either regular over whole shield (male, Fig. 30) or with star-like pattern between setae st4 (female, Fig. 31), posterior margin usually broadly acuminate (variations shown in Figs 27–29); setal lengths - st1 68, 66, 62(56–69), st2 65, 61, 61(57–67), st3 71, 67, 65(62–72), st4 69, 69, 63(59–66); poroid iv1 located posterolaterally to st1, iv2 on margin between st2 and st3, and iv3 on or just inside margin anterior to st4. Seta st5 located between coxae IV, –, –, 53(50–63) long. Opisthogaster: c. 18 pairs of setae on lightly sclerotized cuticle, JV1–3 slightly thicker and longer than the others, lengths - JV1 43, 43, 39(38–42), JV2 40, 39, 37(35–41), JV3, 32, 39, 32(27–37), remainder 18–25; metapodal shields approximately oval, sometimes with irregular outline, c. 24 long; anal shield elongate ovoid, length 104, 107, 97(90–107), greatest width –, 53, 52(51–54), paranal setae 22, 23, 20(19–23) long, postanal seta 31, 27, 28(24–30); four pairs of poroids, one lateral to metapodal shields, one anterolateral to anterior margin of anus, two lateral to anus.
Gnathosoma (Figs 34–38). Gnathotectum: apex acuminate–truncate, with a variable number of serrations and an arc of faint, approximately parallel striae (variations shown in Figs 35–38). Hypostome and basis gnathosomatica: setal lengths - anterior hypostomatic 33, 35, 33(29–34), internal posterior hypostomatic 45, 45, 41(37–48), external posterior hypostomatic 35, 34, 31(28–33), palpcoxal 51, 48, 45(41–50). Chelicera: fixed digit 39, 41, 37(34–38) long, with three subterminal teeth, two distal to and one in region of pilus dentilis; movable digit 54, 54, 51(50–53) long, with three subterminal teeth, which decrease in size distally; dorsal seta subclavate.
Legs. Tarsi II–IV: setae ad1 and pd1 slender, c. 0.3 length of ambulacrum; al1, pl1, av1 and pv1 all slender and setiform.
Remarks. The synonymy of E. sphecophilus and P. britannicus is based on the shared states of characters used to diagnose species of Parasitidae. These are the form of the chelicerae, idiosomal shields and gnathotectum of the deutonymph and adults, endogynium of the adult female and the apophyses of leg II of the adult male. Although form and relative lengths of setae are also generally constant within species, the striking differences seen in some of the adult idiodorsal setae are regarded as intraspecific variation. Measurements of these setae in representatives collected from nests of D. saxonica demonstrate that such variability occurs within a population occurring in the same locality and habitat. Also, setal lengths were found to sometimes vary widely (by as much as 1.6 times) between the members of a particular pair on individual specimens.
The transfer of E. sphecophilus out of Eugamasus Berlese is necessary because of the changes that have occurred in generic boundaries since it was described. Members of Eugamasus are now differentiated from those of Vulgarogamasus by the bifid, rather than spatulate, anterolateral setae (al1 and al2) on the palp genu (Athias-Henriot 1979, Evans & Till 1979, Hyatt 1990, Karg 1993). The placement in Vulgarogamasus is somewhat provisional because of the still unstable generic classification of the Parasitidae. Vulgarogamasus was erected as a subgenus of Parasitus Latreille (Tichomirov 1969), but is now widely used at generic level (e. g., Evans & Till 1979, Hyatt 1980, Karg 1993, Krantz & Ainscough 1990, Mašán & Stanko 2005). The set of character states given to separate Vulgarogamasus differs slightly between authors, but all diagnoses include the following unique combination: dorsal setae z5, j5 and j6 similar in form and length; seta al of the palp femur divided distally into a number of fine processes; female dorsal shield divided and genital shield anteriorly acuminate; male tritosternum normal, and deutonymphal sternal shield and fixed cheliceral digit respectively lack a transverse dark band and terminal process (Evans & Till 1979, Hyatt 1980, Karg 1993). Hyatt (1986) did not discuss the rationale for the generic placement of his new species, but its character states fit the diagnosis for Vulgarogamasus, as opposed to that of Poecilochirus G. & R. Canestrini (Evans & Till 1979, Hyatt 1980, Karg 1993). In the latter, for example, the male podonotal seta z5 is much longer and/or thicker than j5 and j6, while al is spatulate, setiform or spiculate at all life stages. Furthermore, the deutonymphs in the material of E. sphecophilus and from D. saxonica confirm the incorrect original generic placement because they lack the transverse band on the sternal shield that is unique to Poecilochirus.
Vulgarogamasus sphecophilus is one of the few parasitids to have been recorded in association with vespids. Parasitus vesparum Oudemans was described at all postlarval stages from underground nests of Ve sp a vulgaris Linnaeus in the Netherlands (Oudemans 1905, 1914). It was also found in Germany in faeces accumulating under a nest of Ve. vulgaris built in an unused bee hive (Vitzthum 1927). No specimens were recorded on the wasps or, in the case of the German record, in the nest itself. Vitzthum (1927) suggested deutonymphal P. vesparum were brought to the faeces by Diptera identified as Fannia scalaris (Fabricius) (Fanniidae), larvae of which were also present in the faeces. Hyatt (1980) gave one of the records of Parasitus loricatus (Wankel) as ‘on wasp’, although wasp-associated habitats of specimens housed in the Natural History Museum, London, only comprise nests (including that of Ve. vulgaris). With so few records of V. sphecophilus, it is only possible to speculate that it is specific to vespid habitats. Also, because records suggest that species of this genus are not phoretic on other organisms, its method of arrival at the Dolichovespula nests remains to be established.
Members of the Parasitidae are regarded as predators of small arthropods and oligochaetes, but little is known of the dietary preferences of Vulgarogamasus species. The specimens of V. sphecophilus collected from D. saxonica nests were evidently feeding on, or at least damaging, their hosts’ eggs. On several occasions, an egg was observed to deflate and shrivel when the anterior end of a mite was in contact with it. Oophagy was reported previously in parasitids when the impact of certain species on insect populations was investigated in laboratory experiments. Poecilochirus carabi G. & R. Canestrini and P. davydovae Hyatt fed on the eggs of Nicrophorus vespilloides Herbst (Coleoptera: Silphidae) (Beninger 1993, Blackman 1997), and P. monospinosus Wise, Hennessey & Axtell on those of Musca domestica Linnaeus (Diptera: Muscidae) (Wise et al. 1988). In both studies of Poecilochirus carabi and P. davydovae, the clutch size of mite-infested beetles was reduced, but Beninger (1993) found an accompanying increase in brood size, suggesting a benefit to the host because larger immatures have a better chance of survival. Wise et al. (1988) recorded deutonymphal and female P. monospinosus destroying five and 13 eggs per day respectively, and considered this species to play a significant role in suppressing fly populations. The D. saxonica nests in which V. sphecophilus occurred were under investigation by one of us (KRF) to determine whether wasp workers try to stop each other reproducing (‘worker policing’, Foster & Ratnieks 2000). The mites were discovered at the end of the wasp colony cycle in 1999 and their presence rendered observational data on egg removal unclear because it was no longer safe to assume that this was solely carried out by the wasps. Using genetic analysis solved the problem, but these observations suggest that mites can drive a high level of egg mortality in social insect colonies, which may introduce significant error, if not bias, into egg removal data. More generally, it is evident that studies of natural insect populations should consider the potential impact of predatory mites.
description: Published as part of Baker, Anne S. & Foster, Kevin R., 2009, Vulgarogamasus sphecophilus (Cooreman) comb. nov. (Acari: Mesostigmata: Parasitidae): a redescription and new hymenopteran association, pp. 51-64 in Zootaxa 2088 on pages 52-62, DOI: 10.5281/zenodo.187435