Dictyocotes Kéler, 1940

Gustafsson, Daniel R., Tian, Chunpo, Ren, Mengjiao, Li, Zhu, Sun, Xiuling & Zou, Fasheng, 2024, Separation of Goniocotes Burmeister, 1838, and Dictyocotes Kéler, 1940 (Phthiraptera: Ischnocera), with descriptions of four new species, European Journal of Taxonomy 968, pp. 1-36 : 22-25

Genus Dictyocotes Kéler, 1940

Goniocotes Burmeister, 1838: 431 [in partim].

Dictyocotes Kéler, 1940: 153 .

Type species

Goniocotes haplogonus Nitzsch in Giebel, 1866: 390, by original designation.

Diagnosis

Dictyocotes can be separated from Goniocotes s. lat. by the following combination of characters: male mesosome present in Dictyocotes ( Fig. 19 ), but absent in Goniocotes (e.g., Fig. 4 ); male parameres fused to basal apodeme in Goniocotes (e.g., Fig. 4 ), but separate from, and possibly articulating with, basal apodeme in Dictyocotes ( Fig. 19 ); female vulval margin notched medianly in Dictyocotes ( Fig. 20 ; not in D. rolandi ), but rounded or flattened in Goniocotes (e.g., Fig. 5 ); male lateral tergopleurite IX+X slender and small in Goniocotes s. str. ( Fig. 1 ), but larger, triangular or irregular in shape in Dictyocotes ( Fig. 16 ).

For other characters that separate Dictyocotes from Goniocotes s. str., but which are variable within Goniocotes s. lat., see above.

Description

Very small lice of the body louse ecomorph (sensu Johnson et al. 2012). Head shape roughly semicircular or semioval, but may be flattened at frons, temples divergent posteriorly, typically somewhat angular at site of mts1, and with a slight to pronounced occipital bulge at site of mts5. Marginal and ventral carinae uninterrupted; marginal carina moderately wide, may have clear attendant canals connecting to apertures of many setae (e.g., dsms, as1–3, avs1). Dorsal preantennal suture absent. Preantennal nodi variable, in most species elongated. Antennae sexually monomorphic. Eyes often proportionately large. Marginal temporal carina typically broad, with undulating median margin and a distinct occipital nodus originating marginally median to mts5 on each side. Head chaetotaxy: all usual head setae present; as1–3 and avs1 marginal or submarginal; vsms1–2 much separated; pns micro- to mesoseta; s1–6 typically all present as microsetae or in some species as sensilla, and additional sensilla are present in some species; os macrosetae in males, mesosetae in females; pos positioned far posterior to eye; mts1 and mts3 macrosetae, mts5 may be thorn-like, mts2 and mts4 microsetae. Dorsal head densely reticulated.

Prothorax wider than long, with ppss macroseta on postero-lateral corner, which may be extended laterally at site of ppss. Pterothorax variable, but typically pentagonal, may be extended laterally which gives a slightly ‘winged’ appearance; 2 lpts macrosetae on postero-lateral corners, separated by clear gap from 2 ipts macrosetae; single smns meso- or macroseta present submarginally; mpts present or absent. Proepimera extensive, not fused medianly. Meso- and metasterna absent, but mss and mets present. Legs short and stout, most notably with three stout ventral setae on tibiae II–III (likely tbII-v3–5 and tbIII-v3–5, but homology uncertain). Other leg chaetotaxy variable, and many setae very short.; typically: tbI-a1, cII-a1, tbII-a1, tbII-p1–2, tbII-p4–5, tbII-v3, cIII-a1, tbIII-a1, tbIII–p1–2, tbIII-p4–5, tbIII-v3 very short or absent; fII-v2, fII-p1, fIII-v2, fIII–p1 absent. Most sclerotized plates densely reticulated.

Abdomen rounded, more elongated in female. Tergopleurites II–IX+X divided medianly, typically with posterior tergopleurites more reduced compared to anterior tergopleurites in male. Male abdominal segment IX+X with lateral sclerite on each side and central sclerite anterior to dorsal ano-genital opening; lateral tergopleurite large, roughly rectangular or triangular, but generally irregular. Postero-laterally, tergopleurites may be extended to produce small posterior points, particularly in males and often more prominent in posterior segments; postero-lateral corner of tergopleurite VIII may be bifurcated. Paratergal plates prominent. Sternal plates absent in both sexes. Male subgenital plate variable, may be divided submedianly; female subgenital plate absent. Subvulval plates absent. Abdominal chaetotaxy variable among species; anterior seta of tergopleurite II present; rows of tps present on at least tergopleurites II–III in male, and single tps (homology uncertain) may be present on female tergopleurites III–VII just median to psps; psps present on tergopleurites II–VII in both sexes, typically markedly larger than other setae, but may be similar to tps on tergopleurite II. Ventral side with 2–4 sts on each side of segments II–VI, and 2 sts on each side on segments VI. Macrosetae present on ventral side of abdominal segments VII–VIII in both sexes. Most sclerotized plates densely reticulated.

Male genitalia with long, slender basal apodeme (anterior end may reach abdominal segment II), which may have central arched thickening in distal third; postero-lateral corners of basal apodeme may have rugose distal extensions. Mesosome present, reduced are seemingly fused to basal apodeme. Dorsally, mesosome typically as small, transverse gonopore bearing 1–2 visible sensilla on each side (number may be 4 in all species, but difficult to see). Distal to gonopore is typically an elongated thickening on each side, converging towards distal margin of mesosome. Ventral structures of mesosome typically unclear, but may include a single central sclerite or paired lateral sclerites. Parameres not fused to basal apodeme, and may be articulating with postero-lateral corners of apodeme; pst1–2 not visible in any examined species.

Female vulval margin strongly convex medianly, but notched or concave at midline, with numerous (> 15, often much more than 20) long, slender vms and 2–5 short, thorn-like vss on each side; vos microsetae variable in number and position, typically not approaching vulval margin, but may form roughly convergent rows.

Host and geographical distribution

All known species parasitize mid-to-high-altitude hosts in East Asia ( Table 3 ), occurring on hosts in the genera Lophophorus Temminck, 1813 , Tetraophasis Elliot, 1871 , and Crossoptilon Hodgson, 1838 .

Included species

Dictyocotes crossoptiloni ( Liu, 1990: 120) [in Goniocotes ] comb. nov.

Dictyocotes furcatus sp. nov.

Dictyocotes haplogonus (Nitzsch in Giebel, 1866: 390) [in Goniocotes ].

Dictyocotes rolandi ( Gustafsson, Tian & Zou, 2021: 310) [in Goniocotes ] comb. nov.

Dictyocotes tetraophasis ( Liu, 1990: 119) [in Goniocotes ] comb. nov.

Remarks

Four of the five known species of Dictyocotes appear to fall into two distinct groups, with species from Crossoptilon spp. having rounded postero-lateral corners of tergopleurite VIII in both sexes, no tps just median to the psps on female tergopleurites II–VII, and rugose postero-lateral extensions to the basal apodeme, and species from Lophophorus spp. having extended and bifurcated (at least in male) postero-lateral corners of tergopleurite VIII, tps present on female tergopleurites II–VII, and no rugose postero-lateral extensions to the basal apodeme. However, in the single known species from Tetraophasis spp. the postero-lateral corner of tergopleurite VIII is as in the Crossoptilon -infesting group, whereas the female abdominal chaetotaxy and basal apodeme are as in the Lophophorus -infesting group.

As more species of Dictyocotes become known, it may be possible to divide the species into 2–3 species groups, but due to the intermediary morphology of D. tetraophasis we do not here consider these characters to have even informal taxonomic value.

Figures

Figs 18–20. Dictyocotes furcatus sp. nov. 18–19. Holotype, ♂ (BMNH, slide 29, box E0026136). 18. Head, dorsal and ventral views. 19. Genitalia, dorsal view. 20. Female genitalia, ventral view.

Figs 3–5. Goniocotes caoi sp. nov. 3–4. Holotype, ♂ (BMNH, slide 57, box E0026203). 3. Head, dorsal and ventral views. 4. Genitalia, dorsal view. 5. Female genitalia, ventral view. Abbreviations: as1–3 = anterior setae 1–3; avs1 = anterior ventral seta 1; dsms = dorsal submarginal seta; mts1–5 = marginal temporal setae 1–5; os = ocular seta; pns = postnodal seta; pos = preocular seta; pst = parameral seta; s1–6 = sensilla of dorsal head 1–6; vms = vulval marginal seta; vos = vulval oblique seta; vsms 1–2 = ventral submarginal setae 1–2; vss = vulval submarginal seta.

Fig. 1. Goniocotes caoi sp. nov., holotype, ♂ (BMNH, slide 57, box E0026203). Habitus, dorsal and ventral views. Abbreviations: ipts = intermediate pteronotal seta; lpts = lateral pteronotal seta; mets = metathoracic seta; mss = mesothoracic seta; ppss = pronotal post-spiracular seta; ps = paratergal seta; psps = principal post-spiracular seta; ss = sutural seta; sts = sternal seta.

Fig. 16. Dictyocotes furcatus sp. nov., holotype, ♂ (BMNH, slide 29, box E0026136). Habitus, dorsal and ventral views.