Mesalgoides brasiliensis, Hernandes, 2023

Hernandes, Fabio Akashi, 2023, Feather mites (Acariformes: Astigmata) from the yellow-rumped cacique, Cacicus cela (Linnaeus, 1758) (Passeriformes: Icteridae) in Brazil, with description of four new species, Journal of Natural History 57 (2), pp. 257-284 : 274-279

publication ID 10.1080/00222933.2023.2174459


persistent identifier

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scientific name

Mesalgoides brasiliensis

sp. nov.

Mesalgoides brasiliensis sp. nov.

( Figures 10 View Figure 10 –12,13(c))

Type material

Holotype male (#5405), paratypes 2 females (#5406–5407) ex Cacicus cela (Linnaeus, 1758) ( Passeriformes : Icteridae ), BRAZIL, Amazonas State, Lago Cumapi, Jap #754 (E3), 31 July 2007, Jason Weckstein coll.; GoogleMaps paratypes 1 male, 2 females (#5408–5409), same host species, BRAZIL, Bahia State, Ilhéus , campus of UESC, 14.7597222°S, 039.2302778°W, found dead, 14 December 2020, Anibal R. Oliveira coll. GoogleMaps


Male ( Figures 10 View Figure 10 (a,b), 12 (a–12), 13(c)), holotype (measurements for 1 paratype in parentheses). Idiosoma, length × width, 389 (paratype with lobes broken, length not measured) ×255 (249). Length of hysterosoma 287. Prodorsal shield: length 92 (91), width at posterior margin 102 (101); lateral margins gently concave; posterior margin slightly concave, posterior corners nearly rounded; longitudinal median ridges parallel-sided with posterior tips diverging, situated in the anterior third of shield. Setae se separated by 93 (91). Scapular shields well developed dorsally. Hysteronotal shield: length from anterior margin to level of setae h3 273, greatest at level of trochanters III 145 (141), anterior end widely rounded, lateral margins straight. Setae d1 slightly anterior to level of setae d2, setae e1 posterior to level of hysteronotal gland openings gl. Supranal concavity distinct, shaped like an inverted teardrop. Opisthosoma with pronounced postero-lateral tubercles bearing setae f2. Opisthosomal lobes large, lateral lobar digit bearing setae ps2 short, terminal lobar digit about 3.5 times longer than wide, with inner margins straight, outer margin slightly convex. Terminal cleft large, anterior part of cleft inverted V-shaped, posterior parts with rectangular ledges bearing setae ps1. Terminal lamellae on lobar apices acute. Measurements of opisthosomal lobes ( Figure 12 View Figure 12 (e)) (broken in paratype, not measured): length of anterior part of terminal cleft 33; total length of terminal cleft 78; length of terminal lobar digit including terminal lamella 46; width of terminal digit 21; length of terminal digit along its lateral margin 59; width of terminal cleft between terminal digits 44; length of terminal lamellae 17. Distances between idiosomal setae: se:c2 41 (40), c2:d2 64 (59), d2:e2 67 (73), e2:h2 60 (57), h2:h3 27, f2:f2 110, h2:h2 86, h3:h3 67, ps1:ps1 25, ps2:ps2 83, e1: e2 24 (26).

Epimerites I fused into a narrow V, fused tips with a pair of divergent extensions ( Figure 10 View Figure 10 (b)). Epimerites II fused with epimerites III. Epimerites III not connected with epimerites IV. Coxal fields II closed; coxal fields I, III, IV open. Coxal fields IV with sclerotised areas along inner margin of epimerites, setae 4b situated on sclerotised tips of epimerites IV. Genital apparatus situated at midlevel of trochanters III, small, 24 (21) long, 19 (16) wide at base; aedeagus about half the length of genital apparatus. Paragenital apodemes fused, shaped like an inverted U, their posterior ends extending to midlevel of trochanters IV. Setae 4a and g slightly posterior to level of genital apparatus base, and approximately at the same transverse level. Adanal apodemes surrounding anal field not fused at anterior ends. Diameter of adanal suckers 20 (18). Ventral surface of opisthosomal lobes not sclerotised. Distance between ventral setae: 4b:4a 19 (10), g:ps3 66 (75), ps3:ps3 27 (29).

Tibiae I and II with a pair of well-developed acute ventral spines. Tibia III with long antaxial spur, length including spur 104, excluding spur 66 (68); tarsus III 86 (83) long, all setae of this segment filiform ( Figure 12 View Figure 12 (c)). Tarsus IV 19 (21) long, with finger-like paraxial process arising from midlevel of segment and bearing minute seta e, and with bidentate apical processes; seta r about 1/3 as long as seta w; seta d barrel-shaped with discoid cap, situated on bidentate apical processes ( Figure 12 View Figure 12 (d)).

Female ( Figures 11 View Figure 11 (a,b), 12 (f–12), 13(c)), range for 4 paratypes. Length of idiosoma 304–332, width at level of humeral shields 215–216. Prodorsal shield: general form as in male, length 98–105, width 100–112, median ridges about half as long as shield and with strongly divergent posterior ends. Setae se separated by 98–105. Length of hysterosoma 203–216. Hysteronotal shield rectangular in shape, with irregular lateral and posterior margins; greatest length 155–170, width at anterior margin 100–112, width at posterior margin 98–107. Setae c1 at the anterior border of hysteronotal shield. Subhumeral setae c3 about two-thirds the length of setae cp, equal to combined length of segments of femur-genu III. Setae d1 at the same level as setae d2; setae d2 on lateral margins of this shield, setae e2 on posterior margin of this shield; setae e1 at the same level as openings gl. Distance between dorsal setae: se:c2 37–40, c2:d2 54–62, d2:e2 79–96, e2:h2 46–57, d2: d2 103–108, e1: e2 29–36, e2:e2 80–88, h2:h2 65–74, h3:h3 48–62.

Epimerites I free, without sclerotised areas, posterior tips slightly diverging ( Figure 11 View Figure 11 (b)). Epigynum horseshoe-shaped, 65–71 long, 61–70 wide, anterior margin extending beyond tips of epimerites II, posterior ends extending to level of epimerites III; lateral margins with a pair of small acute extensions. Setae g filiform, situated on posterior tips of epigynum. Both pairs of genital papillae situated on inner margins of epigynum. Coxal fields I–IV without sclerotised bands at corresponding trochanters. Bases of setae h2 and h3 rounded, sclerotised and touching each other. Copulatory opening ventral, at posterior margin of anal opening. Primary spermaduct without enlargements, secondary spermaducts not visible ( Figure 12 View Figure 12 (h)). Pseudanal setae ps2, ps3 filiform, 37–48 long. Setae ps1, f2 filiform, 10–12 long. Legs I and II as in male. Setae s and w of tarsi III and setae w and r of tarsi IV thin spiculiform ( Figure 12 View Figure 12 (f,g)). Length of tarsi III and IV 56–61 and 64–69, respectively. Tarsal setae d III, d IV approximately 1.5 times longer than the lengths of corresponding tarsi.

Differential diagnosis

The new species most closely resembles Mesalgoides koki Černý, 1974 described from Chrysomus icterocephalus (Linnaeus, 1766) (= Agelaius icterocephalus ) ( Passeriformes : Icteridae ) in having, in males, the adanal apodemes not fused at their anterior tips, and in females, epimerites I free ( Černy 1974). Mesalgoides brasiliensis sp. nov. is distinguished from the latter species in having the following features: in males, the anterior ends of epimerites I are not connected by a sclerotised bridge, and the posterior tips of paragenital apodemes almost touch the adanal apodemes; and in females, the lateral margins of hysterosomal shield are straight, and the tips of epigynum with convergent tips posterior to setae g. Males of M. koki have their basal parts of epimerites I connected by a strong sclerotised bridge, and the paragenital and adanal apodemes do not touch each other; females of M. koki have lateral margins of hysterosomal shield bearing two median inward concavities, and the tips of epigynum have two diverging extensions posterior to setae g. Females of Mesalgoides johnstoni ( Spory, 1965) described from Agelaius phoeniceus (Linnaeus, 1766) and M. elaeniae ( Černý, 1974) also have epimerites I free; in the latter species, however, the hysteronotal shield is almost trapezoidal in shape, and in M. johnstoni , setae 4a are much shorter, barely reaching halfway to the bases of setae ps3; in females of the new species, setae 4a surpass the base of setae ps3.


The new species is named after the country in which it was collected ( Brasil in Portuguese).


Departamento de Geologia, Universidad de Chile

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