Horniella Raffray

Figs 1–2

Hornia Raffray, 1901: 29 (junior homonym, nec. Riley 1878). Type species: Hornia hirtella Raffray, 1901: 29 (original monotypy).

Horniella Raffray, 1905: 434 (replacement name).

Horniella: Raffray 1904: 369 (key); 1908: 358 (key), 394 (description and distribution); 1911: 165 (catalog); Jeannel 1961: 456 (list); Newton & Chandler 1989: 60 (catalog); Hlaváč & Chandler 2005: 91 (key), 104 (catalog); Nomura et al. 2008: 285 (list of regional fauna, as Hamotopsis); 2010: 24 (list of regional fauna); Yin et al. 2010: 248 (description).

Diagnosis. Body medium to large in size. Head with frontal and vertexal foveae; antennal clubs usually loosely formed by apical three antennomeres, in some species clubs distinct; maxillary palpi with third palpomeres small, triangular, fourth palpomeres large and oval, with truncate base, mesal margins lacking sulcus, with tiny palpal cone. Pronotum with antebasal sulcus connecting median and lateral antebasal foveae; lacking paranotal carinae/ sulci. Elytral discal striae present. Abdomen with tergite IV longer than tergite V.

Description. Length 2.67–4.09 mm. Head usually with short, weak frontal rostrum, defined by prominent antennal tubercles, or rostrum obscure when antennal tubercles only slightly raised in some species, antennal tubercles separated by conspicuously short to short, shallow median sulcus; setose frontal and vertexal foveae welldeveloped (Fig. 1 A); Antennae 11-segmented, simple, lacking modification, clubs usually loosely formed by apical three antennomeres, in some species terminal antennomeres strongly elongate or enlarged, forming distinct clubs; indistinct lateral postantennal pits present; maxillary palpi (Figs 2 A–C) with antennomeres I small, II elongate, widest at middle, stout to slender, III small and triangular, IV enlarged, nearly truncate at bases, lacking sulcus on mesal margins, with tiny palpal cone oblique at apices; gula moderately to strongly swollen, with small gular foveae close in transverse pit (Fig. 1 C); venter with curved lateral spines in species of H. centralis and H. burckhardti groups, spines lacking (Fig. 1 B) in those of H. hirtella and H. gigas groups (definitions of each group see below).

Pronotum (Fig. 1 D) with antebasal sulcus; median and lateral antebasal foveae distinct, as wide as sulcus; lacking paranotal sulcus/carinae; with lateral procoxal foveae (Fig. 1 E).

Each elytron (Fig. 1 F) with two basal foveae, and one to two small subbasal elytral foveae; discal striae usually extending to apical 2/3 of elytral length or more.

Thorax (Fig. 2 D) with broad opening for median mesoventral foveae, lateral mesoventral foveae and small prepectal foveae present; lateral mesocoxal foveae present; with median metaventral fovea, posterior margin of metaventrite with small U-shaped notch.

Abdomen (Figs 2 E–G) with tergite IV (first visible tergite) moderately to distinctly longer than tergite V, with broad basal sulcus, lateral discal carinae on tergite IV variably present; median longitudinal carina variably present on tergites IV–VI; tergites V–VII lacking mediobasal fovea, small basolateral foveae present. Sternite IV (second ventrite) with broad, setose basal sulcus, lacking mediobasal foveae, basolateral foveae developed as large cuticular pockets, with two pairs of antebasal nodules, sternites III–V with basolateral foveae and one median and two lateral small antebasal nodules.

Legs usually with tarsomeres III longest, II about as long as to shorter than III, species of H. gigas group have apices of tarsomeres II extending to middle of tarsomeres III.

Males usually lacking obvious modifications, in many species males have profemora each possessing one ventral spine near base. Aedeagus with median lobe nearly symmetric to strongly asymmetric, endophallus composed of complicated sclerites in many species, or may be much simpler in others; parameres totally reduced in all but one species; dorsal diaphragm opening circular. Usually females can be separated from males by the scapes lacking expansion on lateral margins, the presence of two spines on the ventral margins of the profemora, and the less emarginate posterior margins of tergite VIII and sternite VIII.

Comparative notes. Horniella is most similar to to the genus Hamotopsis Raffray, 1900 (with two species known to occur in eastern Australia) by sharing a similar general appearance and the absence of a sulcus on the mesal margin of the fourth maxillary palpomeres. The two genera can be effectively separated by the more elongate fourth maxillary palpomeres, the pronotum lacking paranotal carinae, the presence of elytral discal striae in Horniella, and abdominal tergite IV is always longer than tergite V. According to Chandler (2001: 407–409), Hamotopsis has stouter fourth segments of the maxillary palpi, the pronotum lacks paranotal carinae, the elytra lack discal striae, and abdominal tergite IV is as long as tergite V.

Discussion. Among species, certain morphological characters can vary greatly but seem gradational. These involve the forms of the antennal clubs, maxillary palpi, and tarsomeres II, presence/absence of the anterolateral genal projections and lateral spines of the head venter, and most distinctly, the aedeagal structures. As the foveal pattern and other characters commonly used for discriminations of genera in Somatipionina are consistent, all species are placed in Horniella here. The following four species-groups are designated and defined, and affinities among the species of each group are discussed in the ‘Differential diagnosis’ section under respective species. In the taxonomic section the species are arranged by country, with the included species of each country treated alphabetically.

The H. centralis group

Diagnostic features: Members share distinct apicolateral genal projections, venter of head with pair of curved lateral spines, and apical portion of aedeagal median lobe with right or left half strongly projecting apicad.

Included species: H. centralis sp. n., H. confragosa sp. n., H. dao sp. n., H. falcis Yin & Li, H. nakhi sp. n., H. schuelkei sp. n., H. sichuanica sp. n., H. tianmuensis sp. n., and H. schwendingeri sp. n.

The H. burckhardti group

Diagnostic features: Members share distinct apicolateral genal projections, and venter of head with pair of curved lateral spines that are similar to those of the H. centralis group. But the apical portion of aedeagal median lobe is not asymmetrically projecting at one side, median lobe is slightly asymmetric to strongly curved, usually with narrowed apex.

Included species: H. hongkongensis sp. n., H. himalayica sp. n., H. asymmetrica sp. n., H. burckhardti sp. n., H. intricata sp. n., H. kaengkrachan sp. n., H. loebli sp. n., and H. phuphaman sp. n.

The H. hirtella group

Diagnostic features: Members lack obvious apicolateral genal projections, and venter of head lacks lateral spine. Aedeagal structure is relatively simple, endophalli usually lack or possess only simple sclerites, and often possess a membranous structure containing many small denticles.

Included species: H. simplaria sp. n., H. hirtella Raffray, H. khaosabap sp. n., H. prolixo sp. n., H. philippina sp. n., H. awana sp. n., and H. cibodas sp. n.

The H. gigas group

Diagnostic features: Apicolateral genal projections and lateral spines on head venter are lacking, each of apical three antennomeres is distinctly elongate, maxillary palpomeres II are conspicuously elongate, tarsomeres II extend to, or near midlength of tarsomeres III, and aedeagal structure is relatively simple, endophallus with sclerites and/or small denticles on membranous structure.

Included species: H. gigas sp. n., H. pilosa sp. n., and H. smetanai sp. n.

Key to male adults

Males of the H. centralis and H. burckhardti species groups can be quickly distinguished from females by the presence of a more or less developed expansion on the lateral margins of the antennal scapes, however this expansion is lacking in the males of the H. hirtella and H. gigas species groups. Most Horniella males typically have a single spine at the ventral margin of the mesofemora, while the females have two similar spines. A more convenient and practical method to sex Horniella specimens before dissection is to examine the terminal of the abdominal segments, males have sternite IX visible as a circular plate between the emargination of tergite VIII and sternite VIII, while females have more flat posterior margins of those tergite and sternite, and lack a visible sternite IX.

Note: The holotype of the previously described H. falcis from Guizhou, Southwest China was erroneously considered to be male. This species is excluded from the following key, and its relationship to other congeners is discussed under the comparative section of that species.

1. Head with apicolateral genal projections more or less distinct, postgenae with pair of curved spines.................... 2

- Head lacking obvious apicolateral genal projections, postgenae lacking spines.................................... 17

2. Apical portion of aedeagal median lobe with right or left half asymmetrically and strongly projecting apically (Figs 4 K–M, 5J–L, 6J–L, 8J–L, 12J–L, 14J–L, 15J–L, 18J–L, 38J–L)..................................... ( H. centralis group)...3

- Apical portion of aedeagal median lobe not asymmetrically projecting at one side, slightly asymmetric (usually) to strongly curved (occasionally), narrowing from base toward apex (Figs 11 J–L, 17J–L, 20J–M, 21A–C, 22L–N, 25J–L, 26J–L, 28J–L, 29J–L, 31J–L, 32J–L, 33A–C, 35J–L, 36K–M, 39J–L, 41J–L, 42J–L, 44J–L, 45J–L, 47J–L).....( H. burckhardti group)... 10

3 Apical projection of aedeagal median lobe located at right half (Figs 4 K–M, 5J–L, 6J–L, 12J–L, 14J–L, 18J–L)........... 4

- Apical projection of aedeagal median lobe located at left half (Figs 8 J–L, 15J–L, 38J–L)............................. 8

4 Apicolateral genal projections with nearly rounded apical margins (Figs 5 C, 18C).................................. 5

- Apical margins of apicolateral genal projections evenly concave, so both apicomesal and apicolateral angulations are distinct (Fig. 4 C), or projections asymmetrically concave apically, only lateral angulation distinct (Figs 12 C, 14C)............... 6

5 Length of aedeagal endophallus relatively short, projection of median lobe with pointed apex (Figs 5 J–L). (China: Guangxi, Guizhou)................................................................................. H. confragosa

- Length of aedeagal endophallus relatively quite long, projection of median lobe with nearly truncate apex (Figs 18 J–L). (China: Zhejiang).......................................................................... H. tianmuensis

6 Apical margin of apicolateral genal projections with both mesal and lateral angulation (Fig. 4 C); aedeagal endophallus composed of single elongate sclerite (Figs 4 K–M). (China: Shaanxi)....................................... H. centralis

- Apical margin of apicolateral genal projections with only lateral angulation distinct (Figs 12 C, 14C); aedeagal endophallus composed of more than one sclerite (Figs 12 K, 14K, 15K)..................................................... 7

7 Apical spur of mesotibiae relatively shorter (Fig. 12 F); aedeagus relatively more elongate in dorso-ventral view (Figs 12 J, L), endophallus composed of two elongate sclerites (Fig. 12 K). (China: Yunnan)................................ H. nakhi

- Apical spur of mesotibiae relatively longer (Fig. 14 F); aedeagus relatively stouter in dorso-ventral view (Figs 14 J, L), endophallus composed of one elongate and two much shorter sclerites (Fig. 14 K). (China: Yunnan)........... H. schuelkei

8 Antennae with scapes strongly projecting basolaterally (Fig. 15 B); apical margin of apicolateral genal projections nearly truncate (Fig. 15 C); apical projection of aedeagal median lobe with pointed apex in dorso-ventral view (Figs 15 J, L)..................................................................................................... H. sichuanica

- Antennae with scapes slightly projecting basolaterally (Figs 8 B, 38B); apical margin of apicolateral genal projections strongly to weakly concave (Figs 8 C, 38C); apical projection of aedeagal median lobe with nearly rounded apex in dorso-ventral view (Figs 8 J, L; 38J, L).................................................................................... 9

9 Apical margin of apicolateral genal projections strongly concave (Figs 8 C); mesotrochanters with relative short ventral spine (Fig. 8 G); apical projection of aedeagal median lobe with roundly expanded apex in lateral view (Fig. 8 K). (China: Sichuan)................................................................................................ H. dao

- Apical margin of apicolateral genal projections slightly concave (Figs 38 C); mesotrochanters with markedly long ventral spine (Fig. 38 G); apical projection of aedeagal median lobe with lengthy, truncate apex (Fig. 38 K). (Thailand: Chiang Mai).............................................................................................. H. schwendingeri

10 Profemora each with two ventral spines (Fig. 32 E), mesotrochanters lacking ventral spine or projection (Fig. 32 G). (Thailand: Chiang Mai).................................................................................... H. loebli

- Profemora each with one ventral spine (Figs 11 E, 20E, 25E, 26E, 28E, 29E, 35E), mesotrochanters with weakly to well-developed ventral spine or projection (Figs 11 G, 20G, 25G, 26G, 28G, 29G, 35G)....................................... 11

11 Mesotrochanters each with one long, broad, apically truncate ventral projection (Fig. 25 G); aedeagal median lobe strongly curved rightwards and with strongly narrowed apex in dorso-ventral view (Figs 25 J, L). (Thailand: Prachin Buri).................................................................................................. H. asymmetrica

- Mesotrochanters with ventral projection or spine conspicuously short to moderately short (Figs 11 G, 20G, 26G, 28G, 29G, 35G); apex of aedeagal median lobe more or less truncate in dorso-lateral view (Figs 11 J, L; 20J, L; 26J, L; 28J, L; 29J, L; 35J, L)................................................................................................. 12

12 Mesal margins of compound eyes strongly and roundly emarginate (Fig. 20 C). (Nepal: Bāgmatī añcal; India: Uttarakhand)............................................................................................. H. himalayica

- Mesal margins of compound eyes rounded, not emarginate (Figs 11 C, 26C, 28C, 29C, 35C)......................... 13

13 Mesotrochanters each with one thick, sharp ventral spine (Fig. 35 G); apical portion of aedeagal median lobe distinctively asymmetric in dorso-ventral view (Figs 35 J–L). (Thailand: Khon Kaen)............................... H. phuphaman

- Ventral spine of mesotrochanters not sharp (Figs 11 G, 26G, 28G, 29G); apical portion of aedeagal median lobe nearly symmetric to slightly asymmetric in dorso-ventral view (Figs 11 J, L; 26J, L; 28J, L; 29J, L)................................ 14

14 Mesotrochanters each with one short, apically narrowed ventral spine (Figs 11 G, 26G); apex of aedeagal median lobe horizontally truncate in dorso-ventral view (Figs 11 J, L; 26J, L)...................................................... 15

- Mesotrochanters each with one extremely short, apically truncate ventral spine (Figs 28 G, 29G); apex of aedeagal median lobe obliquely truncate in dorso-ventral view (Fig. 28 J, L; 29J, L).................................................. 16

15 Basolateral expansion of scapes barely noticeable (Fig. 11 B); apical half of aedeagal median lobe slightly bent rightwards (Figs 11 J, L), endophallus composed of long, curved sclerite and much shorter one at base of long sclerite (Fig. 11 J). (China: Hong Kong)............................................................................. H. hongkongensis

- Basolateral expansion of scapes strongly indicated (Fig. 26 B); aedeagal median lobe not bent (Figs 26 J, L), endophallus composed of long, curved sclerite and two much shorter ones at middle and base of long sclerite (Fig. 26 J). (Thailand: Chiang Mai)......................................................................................... H. burckhardti

16 Basolateral expansion of scapes indistinct (Fig. 29 B); aedeagal endophallus has longest sclerite with rightward-curved apex (Fig. 29 J). (Thailand: Phetchaburi)........................................................... H. kaengkrachan

- Basolateral expansion of scapes strongly indicated (Fig. 28 B); aedeagal endophallus has longest sclerite with leftward-curved apex (Fig. 28 J). (Thailand: Mae Hong Son, Chiang Mai)............................................... H. intricata

17 Head distinctly longer than wide; apical three antennomeres each markedly elongate (Figs 40 B, 43A–B); second tarsomeres extending to middle of third tarsomeres.................................................... ( H. gigas group)...18

- Head usually only slightly longer than wide; apical three antennomeres more robust (Figs 16 A, 19B, 30A, 34B, 37B, 40A, 46); second tarsomeres simple, not extended.................................................. ( H. hirtella group)...20

18 Length of body over 4 mm; aedeagus with pair of membranous but clearly visible parameres (Figs 42 K, L). (Malaysia: Sabah).............................................................................................. H. gigas

- Length of body less than 3.7 mm; aedeagus lacking parameres (Figs 44 L, 45K)................................... 19

19 Ventral margins of mesofemora (Fig. 44 G) and metatibiae (Fig. 44 I) with dense long hairs. (Malaysia: Sabah)...... H. pilosa

- Ventral margins of mesofemora and metatibiae normally setose, lacking dense long hairs (Fig. 45 G). (Malaysia: Sabah)................................................................................................ H. smetanai

20 Mesal margin of protibiae with one spine at apical third (Fig. 17 F). (China: Guangxi)....................... H. simplaria

- Protibiae with mesal margin lacking spine (Figs 22 C, 31F, 36F, 39F, 41F, 47F).................................... 21

21 Apical three antennomeres each nearly oval, forming distinct club (Figs 30 A, 34B)................................ 22

- Apical three antennomeres each not oval, usually loosely clubbed (Figs 37 B, 40A, 46) [club distinct in H. hirtella (Fig. 19 B)]................................................................................................... 23

22 Apical portion of metatibiae with large mesal cavity (Figs 34 B, 36I); aedeagus relatively much more elongate in dorso-ventral view (Figs 36 K, M). (Thailand: Chiang Mai)......................................................... H. prolixo - Apical portion of metatibiae lacking cavity (Figs 30 A, 31I); aedeagus relatively more stout in dorso-ventral view (Figs K, M). (Thailand: Chanthaburi)...................................................................... H. khaosabap

23 Antennae relatively more distinctly clubbed (Fig. 19 B); ventral margin of profemora with one small and one much bigger spine (Fig. 22 B); aedeagus relatively elongate, endophallus composed of many small denticles (Fig. 22 L). (Sri Lanka: Northern, North Central, Central, Uva).................................................................. H. hirtella

- Antennae loosely clubbed (Figs 37 B, 40A, 46); profemora each with two tiny ventral spines (Figs 39 E, 41E, 47E); aedeagus elongate, endophallus lacking small denticles (Figs 39 J, 47J), if denticles present, than form of aedeagus stout (Fig. 41 J).. 24

24 Aedeagus very stout, endophallus composed of many small denticles (Fig. 41 J). (West Malaysia: Pahang)........ H. awana

- Aedeagus elongate, endophallus lacking denticles (Figs 39 J, 47J)............................................... 25

25 Aedeagal median lobe evenly narrowing from middle toward apex in dorso-ventral view, with rounded apex (Figs 39 J, L). (The Philippines: Laguna)..................................................................... H. philippina

- Aedeagal median lobe broad throughout in dorso-ventral view, right side of apex with truncate expansion (Figs 47 J, L). (Indonesia: West Java).............................................................................. H. cibodas