Hydropsyche homunculus Schmid 1965

Xie, Yue, Xu, Ji-Hua, Wang, Bei-Xin & Sun, Chang-Hai, 2017, Descriptions of pupae of two Hydropsyche species from China (Insecta, Trichoptera, Hydropsychidae), Zootaxa 4341 (4), pp. 539-553: 541-551

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https://doi.org/10.11646/zootaxa.4341.4.6

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scientific name

Hydropsyche homunculus Schmid 1965
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Hydropsyche homunculus Schmid 1965 

( Figs. 2–10View FIGURE 2View FIGURES 3 – 7View FIGURE 8View FIGURES 9 – 10)

Pupa (Male): Body length 7‒8 mm. Body (in alcohol) brown. Head brown; eyes black; antennae and palpi brown. Thorax brown oVerall, pronotum with setal warts white, mesoscutellum white, metathorax light brown; wingpads dark brown; legs with inner sides yellowish brown and outer surfaces dark brown. Abdomen yellowish brown ( Figs. 2A –2CView FIGURE 2).

Antennae filiform, slightly shorter than body ( Figs. 2A, 2BView FIGURE 2), each with scape thick and rounded and pedicel long and slender, flagellar segments each longer than wide. Labrum ( Fig.3View FIGURES 3 – 7) somewhat membranous, pentagonal in anterior View, coVered with tiny spines. Mandibles ( Figs. 4L, 4RView FIGURES 3 – 7) subtriangular in dorsal View, each with base thickened, then narrowed to serrate apex, inner margin concaVe; left mandible ( Fig. 4LView FIGURES 3 – 7) with about 10 basodorsal setae and seVeral setae on basolateral margin and with third and fourth tooth smaller among fiVe apical teeth; right mandible ( Fig. 4RView FIGURES 3 – 7) with same distribution of setae, apex with 4 teeth of about same size. Maxillary palpi ( Fig. 5L, 5RView FIGURES 3 – 7) each 5-segmented: segment I subtriangular; segment II about 3 times as long as segment I, progressiVely thickened from base to apex; segment III elliptical; segment IV slender, about same length as segment III; segment V about 1.5 times as long as total length of segments I –IV. Labium ( Fig. 6View FIGURES 3 – 7) subelliptical, with basal margin forming rounded lobe; labial palpi each 3-segmented, segments I and II subrectangular, equal in length; segment III about 4 times as long as segment II.

Sheaths of forewings and hind wings reaching at least posterior margins of abdominal segment IV or to middle of segment V in some indiViduals ( Figs. 2A, 2BView FIGURE 2). Forelegs ( Fig. 7AView FIGURES 3 – 7) shortest, midlegs longest ( Fig. 7BView FIGURES 3 – 7); foretibiae each with 2 apical spurs of approximately same length ( Fig. 7AView FIGURES 3 – 7); midtibiae each with inner preapical and apical spurs about 2 times as long as outer preapical one ( Fig. 7BView FIGURES 3 – 7); hind tibiae each bearing 2 preapical spurs on distal 1/3 and 2 apical spurs with outer spurs slightly shorter than inner ones ( Fig. 7CView FIGURES 3 – 7).

Abdomen somewhat spindle-shaped ( Figs. 2A –2CView FIGURE 2). In dorsal View terga I ‒III each bearing transVerse row of moderately long setae, such setae on segments IV and V much longer, terga VI ‒VIII with sparse long setae, tergum IX with long dorsolateral setae ( Figs. 2AView FIGURE 2, 8View FIGURE 8). Apical processes strongly bristled ( Figs. 10A –10CView FIGURES 9 – 10). In Ventral View sterna I ‒VII each bearing transVerse row of short setae, segments IX and X strongly setose.

Anterior pair of dorsal hook plates on abdominal terga II –VIII, with hooks usually only on posterior edges ( Fig. 8View FIGURE 8, IIa –VIIIa): IIa transVerse-suboVal; IIIa transVerse-suboVal, with strong and fine teeth alternately arranged; IVa transVerse-oVal; Va with Very stout teeth irregularly spaced; VIa, VIIa, and VIIIa subequal in size, each with length nearly two times width and with teeth much stronger than supporting hook plate, these teeth irregularly spaced on VIa and VIIa. Posterior pairs of dorsal hook plates on terga III and IV ( Fig. 8View FIGURE 8, IIIp, IVp): IIIp transVerseoVal, with width about 4 times length and hooks on all edges of each hook plate; IVp transVerse-elliptical. Hook numbers on each hook plate as follows: IIa 11–15; IIIa 17–19; IIIp 51–57; IVa 12–13; IVp 9–10; Va 7–8; VIa 6–9; VIIa 6; VIIIa 4–5.

Gills ( Fig. 9View FIGURES 9 – 10). Pairs of Ventrolateral gills on abdominal segments III –VII: those on segments III, IV, V, and VII each with one small single gill; those on segment VI with two gills. Ventral gills situated near anterior margin of segments III –VII, each with 2 stalks; numbers of gill stalks of Ventrolateral and Ventral gills shown in Table 3.

Segment IX ( Figs. 10A –10CView FIGURES 9 – 10) subelliptical. Anal appendages long and sclerotized, in dorsal and Ventral Views each with lateral margin straight and inner margin concaVe; apex concaVe; apicomesal triangular point much larger than apicolateral one. In Ventral View, male inferior appendages each tapering from base to rounded apex and slightly curVed inwards.

Material examined. CHINA, Zhe-jiang ProVince , Lin’an County, Gao-hong Town , Mt. Da-shan, 30.39°N, 119.62°E, altGoogleMaps  . 507 m, 20 Sept. 2015, collected by Yue Xie & Ji-hua Xu, 3 male pupae. Distribution. China (Zhe-jiang). 

Hydropsyche simulata Mosely 1942 

(Figs. 11–19)

Pupa (Male): Body length 8‒9 mm. Body (in alcohol) yellowish brown. Head yellowish brown dorsally, and brown anteriorly and laterally, setal warts yellow with black hairs; eyes gray; antennae and palpi yellowish brown. Thorax yellowish brown, but mesoscutellum pale brown; wingpads dark brown and legs yellowish brown. Abdomen yellowish brown ( Figs. 11A –11CView FIGURE 11).

Antennae filiform, slightly longer than body ( Figs. 11A, 11BView FIGURE 11), each with scape thick and rounded and pedicel slender, flagellar segments longer than wide. Labrum ( Fig. 12View FIGURES 12 – 16) in anterior View trilobate, densely setose; middle lobe subrectangular, with anterior margin slightly concaVe, each lateral lobe small, semicircular. Mandibles ( Fig. 13L, 13RView FIGURES 12 – 16) conical, each with base thick, then suddenly narrowed to serrate apex, inner margin concaVe, each mandible with two groups of seVeral setae in each group (basodorsal and basolateral groups); left mandible ( Fig. 13LView FIGURES 12 – 16) apically with 4 teeth of about same size; right mandible ( Fig. 13RView FIGURES 12 – 16) apically with 5 teeth, of which third tooth smallest. Maxillary palpi ( Fig. 14L, 14RView FIGURES 12 – 16) each 5-segmented: segment I subrectangular; segment II slender, about 2.5 times as long as segment I; segment III elongate-elliptical, half as long as segment II and slightly longer than segment I; segment IV slender, with base narrow and subapex slightly thicker; segment V longest, slightly longer than total length of segments I ‒IV. Labium ( Fig. 15View FIGURES 12 – 16) subelliptical, with basal margin forming rounded lobe; labial palpi each 3-segmented, segments I and II subelliptical, equal in length; segment III longest, about 3 times as long as segment II.

Sheaths of forewings and hind wings reaching end of abdominal segment III or to beginning of segment VI ( Figs. 11A, 11BView FIGURE 11). Forelegs ( Fig. 16AView FIGURES 12 – 16) shortest, hind legs longest ( Fig. 16CView FIGURES 12 – 16); forelegs each bearing 2 apical spurs, with outer apical spur slightly longer than inner one ( Fig. 16AView FIGURES 12 – 16); midlegs each with inner preapical and apical spurs about 2 times as long as outer ones ( Fig. 16BView FIGURES 12 – 16); hind legs each bearing 2 preapical spurs almost equal in length, and 2 apical spurs with outer apical spur slightly longer than inner one ( Fig. 16CView FIGURES 12 – 16).

Abdomen somewhat spindle-shaped ( Figs. 11A –11CView FIGURE 11). In dorsal View terga I ‒III each bearing transVerse row of moderately long setae, but such setae in segment IV and V much longer; terga VI ‒VIII with sparse long setae; tergum IX with long setae dorsolaterally ( Figs. 11AView FIGURE 11, 17View FIGURE 17). Apical processes each strongly bristled. In Ventral View sterna I ‒VII each bearing transVerse row of short setae, segments IX and X strongly setose.

Anterior pairs of dorsal hook plates present on abdominal terga II to VIII, with hooks usually only on posterior edges ( Fig. 17View FIGURE 17, IIa –VIIIa): IIa transVerse-suboVal; IIIa transVerse-suboVal, with strong and fine teeth alternately arranged; IVa transVerse-oVal; Va, VIa, VIIa, and VIIIa almost equal in size, longer than wide, each with teeth arranged in two groups. Posterior pairs of dorsal hook plates on terga III and IV ( Fig. 17View FIGURE 17, IIIp, IVp): IIIp transVerseoVal, with hooks on all edges; IVp transVerse-elliptical. Hook numbers on each hook plate as follows: IIa 14–15; IIIa 18–19; IIIp 43–52; IVa 11; IVp 14; Va 8–12; VIa 9–11; VIIa 6–8; VIIIa 7–9.

Gills ( Fig. 18A, 18BView FIGURES 18 – 19). Pairs of Ventrolateral gills on massiVe teat-shaped bases on abdominal segments II –VII: Those on segments III, IV, and VII each with 1 small gill; segment V with 2 gills; segment VI with 3 gills. Ventral gills near anterior margins of abdominal segments II –VII, single or 2-stalked; numbers of gill stalks of Ventrolateral and Ventral gills are shown in Table 4.

Segment IX ( Figs. 19A –19CView FIGURES 18 – 19) in dorsal View somewhat trapezoidal. Anal appendages long and strongly sclerotized, in dorsal and Ventral Views each with lateral margin and inner margin constrict at midlength; apex concaVe; apicomesal triangular point much larger than apicolateral one. In Ventral View, male inferior appendages each tapering from base to rounded apex and slightly curVed inwards.

Material examined. CHINA, Zhe-jiang ProVince , Lin’an County, Gao-hong Town : Heng-du, 30.36°N, 119.56°E, alt. 329 m, 21 Sept. 2015, collected by Yue Xie & Ji-hua Xu, 1 male pupaGoogleMaps  ; Mt. Da-shan , 30.39°N, 119.62°E, alt. 507 m, 20 Sept. 2015, collected by Yue Xie, Ji-hua Xu, Xiang-juan Wu, Lei Zhang & Zhen Liu, 2 male pupae.GoogleMaps 

Distribution. China (An-hui, Fu-jian, Guang-dong, Guang-xi, Jiang-xi, Zhe-jiang).

Discussion

Pupae of Hydropsyche  species are similar morphologically, and can be diagnosed mainly by the shapes of labrum, mandibles, legs, anterior and posterior dorsal plates of hooks on abdominal segments II ‒VIII, and anal appendages (Bueno-Soria 1984; Denning 1943; LepneVa 1964; Philipson 1953; Rutherford 1985). LepneVa (1964) also noticed that length of antennae, length of wing sheaths, and the shape of lateral and Ventral gills Varied among species. Of these diagnostic characters, mandibles, lateral and Ventral segmental gills among described pupae show great conformity in shape, while teeth of each plate of hooks on segment II ‒VIII Varied among indiViduals within the same species; therefore, we don’t consider these characters suitable for diagnosing hydropsychid pupae exclusiVely.

Based on the shape of the phallus, Oláh & Johanson (2008) ascribed H. homunculus  and H. simulata  to their H. newae  Species Group. The group now contains more than 100 species recognized mostly by adult males, of which pupae of only three species, i.e., H. morosa  , H. newae  , and H. bronta  were preViously described. We add descriptions of pupae of two more Hydropsyche  species for the group, and tentatiVely diagnose them as follows.

The pupa of H. homunculus  can be separated from other known pupae within the group in that: (1) the antennae are shorter than the body; (2) the labrum is pentagonal, somewhat membranous, with tiny spines, rather than heaVily bristled as in other pupae; (3) the anterior plates of hooks on segment IIa are oVal, wider than long, and each VIa is about 2 times as long as wide.

The pupa of H. simulata  can be diagnosed from other pupae in that: (1) antennae are about as long as the body; (2) the labrum is strongly bristled, trilobite with the middle lobe large, posterior margin straight, and lateral lobes small; and (3) hook plates IIa are each elongate-oVal and those of VIa are slightly longer than wide.

In conclusion, we found that pupal stages of the H. newae  Species Group can be separated from each other by the diagnostic characters mentioned aboVe; howeVer, because so few pupal stages haVe been described, we cannot determine distinctiVe characters to define the species group in pupal stages. EVidently much further study is required to understand the relationships to other species groups within the genus, in adults, pupae, and larVae.

TABLE 3. The numbers of abdominal gills of pupal Hydropsyche homunculus.

SEGMENT VENTROlaTERal VENTRal
II 0 2
III 1 2
IV 1 2
V 1 2
VI 2 2
VII 1 2

TABLE 4. The numbers of abdominal gills of pupal Hydropsyche simulata.

SEGMENT VENTROlaTERal VENTRal
II 0 1
III 1 2
IV 1 2
V 2 1
VI 3 2
VII 1 1