Pentatrichosiphum (Sternorrhyncha: Aphididae), a generic account with the description of a new species from Hainan, China

The aphid genus Pentatrichosiphum Basu, 1969 is reviewed. Pentatrichosiphum longirostrum n. sp. from Lauraceae in Hainan, China is described. Pentatrichosiphum luteum Basu, 1969 is recorded for the first time from China, the first record of this genus. Some hitherto unknown morphs of P. luteum are described. The genus is redefined and keys to the four known species worldwide are also provided. The taxonomic status of Pentatrichosiphum is discussed based on morphological characters. Type specimens are deposited in the Zoological Museum, Institute of Zoology, Chinese Academy of Sciences, Beijing, China (ZMCAS).


Introduction
Pentatrichosiphum was erected for Pentatrichosiphum luteum from India by Basu in 1969. Later, the genus was transferred to the genus Greenideoida van der Goot as a subgenus by Raychaudhuri and Chatterjee (1980). Most workers have accepted and followed this action (Ghosh and Agarwala 1993;Remaudière and Remaudière 1997;Wegierek and Peñ alver 2002). However, Noordam (1994) regarded Pentatrichosiphum as a valid genus. Raychaudhuri and Chatterjee (1980) and Ghosh and Agarwala (1993) provided keys to the subgenera and species within Greenideoida of India and Bhutan, including two known species of the Pentatrichosiphum, i.e. Pentatrichosiphum lambersi (Basu, 1964) and P. luteum Basu, 1969. Blackman andEastop (1994) included only these two species, and Noordam (1994) re-described the type species, P. luteum. A third species, P. turolensis (Wegierek and Peñ alver 2002), was discovered in lacustrine oil-shales from the Lower Aragonian (Lower Miocene, about 18-19 million years) of Rubielos de Mora Basin in Teruel, Spain by Wegierek and Peñ alver (2002). Here we treat two related species, Pentatrichosiphum longirostrum n. sp. and P. luteum, which is a new record for China.
Genus Pentatrichosiphum is represented by three extant species and one fossil species worldwide, of which three extant species all occur in Southeast Asia (Noordam 1994;Remaudière and Remaudière 1997;Wegierek and Peñ alver 2002). In this paper, the genus Pentatrichosiphum is redefined. The taxonomic status of the genus is discussed based on morphological characters.

Material and methods
Detailed descriptions and figures of the three previously described species are from Basu (1964Basu ( , 1969, Ghosh and Agarwala (1993), Noordam (1994), and Wegierek and Peñ alver (2002). All specimens studied are deposited in the Zoological Museum, Institute of Zoology, Chinese Academy of Sciences, Beijing, China (ZMCAS).
Aphid terminology follows Noordam (1994) and Qiao (2000). The unit of measurement is millimetres (mm). The taxonomic system of Remaudière and Remaudière (1997) is followed here.

Diagnosis
Body elliptical, posterior of abdomen tapered. Frons convex; frontal tubercles indistinct. Eyes with numerous facets and ocular tubercle. Between the eyes with three to five hairs, two of these in the median more sturdy, the tips pointed or ramose. Antennae four-or fivesegmented, about 0.3-0.56 body length; processus terminalis about 0.5-26 as long as base of the segment. Ultimate rostral segment long, wedge-shaped, distinctly longer than second hind tarsal segment. Mesosternal furca with two arms separated. First tarsal chaetotaxy: 5, 5, 5. Abdomen without marginal tubercles. Hairs dorsally on the abdomen with sharp points or ramose. Siphunculi long, barrel-shaped, with some spinulose imbrications on apex, without reticulation, straight or bent outwards. Cauda with a broadly rounded posterior margin, without a median processus. In alates, median vein of the fore wing twice branched, hind wing with one oblique vein.

Distribution
China, Bhutan, India, Indonesia, Spain. Basu (1969) erected the genus Pentatrichosiphum and considered it closely related to Greenideoida, differing from it in having vein M in the fore wing twice-branched, and hind wing with one oblique vein. Raychaudhuri and Chatterjee (1980) considered the characters of wing vein used by Basu (1969) for separating the genus Pentatrichosiphum from Greenideoida were insufficient, and Pentatrichosiphum was treated as a subgenus of Greenideoida. The blunt ultimate rostral segment and rostral segments IV and V indistinctly divided have previously been described by Raychaudhuri and Chatterjee (1980) and Ghosh and Agarwala (1993) as being important diagnostic characters for Greenideoida. Except for the above diagnostic characters, Noordam (1994) reviewed Pentatrichosiphum from Java and used the following main diagnostic characters to differentiate it from Greenideoida: ultimate rostral segment 1.75-1.96 times as long as second hind tarsal segment; antennae 0.42-0.516 as long as body; body hairs thick and long, e.g. antennal hairs 0.13-0.16 mm. While examining the specimens of Pentatrichosiphum from Hainan, China, we found the ultimate rostral segment of the new species was more slender and long, 2.46-2.736 as long as second hind tarsal segment and its rostral segments IV and V were distinctly divided. On the basis of the above, we tentatively suggest that Pentatrichosiphum should be treated as a valid genus, and follow Noordam's view (1994 (Basu, 1964) Pentatrichosiphum lambersi (Basu, 1964) Greenideoida lambersi Basu 1964, p 232. Greenideoida (Pentatrichosiphum) lambersi Basu: Raychaudhuri and Chatterjee 1980, p 351;Ghosh and Agarwala 1993, p 260;Remaudière and Remaudière 1997, p 176.

Notes
All information on this species is from Basu (1964) and Raychaudhuri and Chatterjee (1980).

Description
Apterous viviparous female. Body yellow in life. For general measurements see Table I. Mounted specimens: body oblong oval ( Figure 14). Head: ocular tubercles, distal one-third of antennal processus terminalis and rostral segment V pale brown, other parts colourless. Head fused with prothorax. Dorsum of head with transverse wrinkles in anterior part, antennal segments III and IV with transverse imbrications. Median portion of front slightly convex, antennal tubercles slightly developed ( Figure 1). Dorsal hairs thick and long, mostly ramose on distinct tubercles; ventral hairs fine, long and pointed. Head with two pairs of frontal hairs, one or two pairs of dorsal hairs between antennae, and three or four pairs of dorsal hairs between eyes. Eyes multi-faceted, with about 18-20 facets, with ocular tubercles. Antennae four-segmented or occasionally five-segmented (Figures 2, 3), proportion of segments I-IV: 16-18, 13-16, 100, 31-32+47-53, respectively. Antennal hairs stout and long, ramose or pointed at apex, segments I-IV each with 2 or 3, 5 or 6, 11-15, 2+0 hairs, respectively; apex of processus terminalis with three to five hairs. Rostrum reaching abdominal segment II; ultimate rostral segment slender and long wedge-shaped ( Figure 5), with three pairs of primary hairs and three to five pairs of secondary hairs.
Thorax: dorsum of thorax colourless. Dorsal hairs of thorax thick and long, pointed or ramose on distinct tubercles. Pronotum with 16-20 hairs, among which two pairs of spinal and two pairs of marginal hairs distinct thick and long; mesonotum with 36-38 hairs, among which one pair of spinal, one pair of pleural, and one pair of marginal hairs distinct thick and long; metanotum with 28-30 hairs, among which one pair of spinal, two pairs of pleural, and one pair of marginal hairs distinct thick and long. Mesosternal furca weakly sclerotized, with arms separated (Figure 4), length of single arm 0.09-0.13 mm, 2.57-3.256 widest diameter of antennal segment III. Legs colourless, except claws brown. Femora with weakly transverse imbrications. First tarsal chaetotaxy: 5, 5, 5. Abdomen: colourless. Dorsal hairs of abdomen thick and long, pointed or ramose, most dorsal hairs on distinct tubercles, ventral hairs fine and pointed, dorsal hairs 1.50-6.30 times as long as ventral hairs. Abdominal tergites I-V with 24-26, 38-42, 44-50, 34-38, 34-36 hairs, respectively; tergite I with one pair of spinal, and two pairs of marginal hairs thick and long; tergites II-V each with one pair of spinal, one pair of pleural, and one to three pairs of marginal hairs thick and long; tergite VI with two pairs of spinal and four pairs of pleural hairs; tergite VII with two pairs of spinal hairs; tergite VIII with one pair of spinal  Fourth-instar viviparous nymph. For general measurements see Table II. As in apterous vivipara but differing as follows. Appendages slightly shorter. Length of hairs on antennal segment III 4.316 widest diameter of the segment. Hind femur 1.296 antennal segment III; hind tibia 0.316 body length. Length of hairs on hind tibia 1.686 mid-diameter of the segment. Siphunculi 0.396 body length. Eyes with five facets. Genital plate with 15 hairs.
Fourth-instar alatoid nymph (Figure 15). For general measurements see Table II. As in apterous vivipara but differing as follows. Antennal hairs in segments I-IV each with 3 or 4, 3 or 4, 9-11, 2+0 hairs, respectively, apex of processus terminalis with two to four hairs. Secondary rhinaria transversely elliptical, on segment III with 17-19 over its whole length ( Figure 10); primary rhinaria round and weakly ciliated. Pronotum with 14 hairs, among which one pair of spinal and two pairs of marginal hairs distinct thick and long; mesonotum with 46 hairs, among which two pairs of spinal, three pairs of pleural, and four pairs of marginal hairs distinct thick and long; metanotum with 18 hairs, among which one pair of spinal, one pair of pleural, and three pairs of marginal hairs thick and long. Abdominal tergites I-V each with one pair of spinal, one pair of pleural, and three pairs of marginal weakly sclerotized patches. Abdominal tergites I-III and V each with one pair of spinal, one pair of pleural, and two or three pairs of marginal hairs distinct thick and long, respectively; tergite IV with two pairs of spinal, two pairs of pleural, and three pairs of marginal hairs distinct thick and long; tergite VI with two pairs of spinal and three pairs of pleural hairs, tergite VII with two pairs of spinal hairs, and tergite VIII with one pair of spinal hairs. Siphunculi with densely spinulose in apical 3/16; with 63-84 long and short hairs. Genital plate with 9-21 hairs.
Embryo (in apterous viviparous female). Body long, oval and entirely pale (Figure 11). Head fused with prothorax. Median front slightly convex, antennal tubercles indistinct. Eyes with three facets. Antennae four-segmented, 0.296 body length, segments III and IV with transverse imbrications (Figures 12, 13); length in proportion of segments I-IV: 38: 46: 100: 69+108, respectively; processus terminalis 1.576 base of segment IV; segments I-IV each with 0, 1, 2, 0+0 stout and long hairs, respectively; apex of processus terminalis with three hairs; length of hairs on segment III 2.566 widest diameter of the segment. Rostrum reaching abdominal segment V; ultimate rostral segment slender and long wedge-shaped, 4.866 basal width, 2.436 second hind tarsal segment. Dorsal hairs thick and long, pointed or ramifying. Head with one pair of frontal hairs, one pair of dorsal hairs between antennae, and three pairs of dorsal hairs between eyes. Pronotum with one pair of spinal hairs and one pair of fine and short marginal hairs; mesonotum with one pair of spinal hairs, one pair of fine pleural hairs, and two pairs of short and pointed marginal hairs; metanotum with one pair of spinal and two pairs of marginal hairs. Abdominal tergite I with one pair of spinal and one pair of marginal hairs; tergites II-V each with one pair of spinal, one pair of pleural, and one pair of marginal hairs; tergite VI with one pair of spinal and one pair of pleural hairs; tergites VII and VIII each with one pair of spinal hairs. First tarsal chaetotaxy: 2, 2, 2. Siphunculi present.

Biology
This species infests the young leaves of the host plant.

Comments
This new species can be easily separated from other congeneric species by apterous viviparous female with antennae four-segmented; ultimate rostral segment 6.75-8.67 times as long as basal width and 2.46-2.73 times as long as second hind tarsal segment; longest hairs on antennal segment III about 4.00-4.60 times as long as widest diameter of the segment.

Description
The morphological characters of the apterous viviparous female and alate viviparous female are the same as in the descriptions by Ghosh and Agarwala (1993) and Noordam (1994).
First-instar nymph. Body yellow in life.
Mounted specimens: body long oval, 3.216 width. Eyes and apical part of antennal segment IV pale brown, others pale.
Head: dorsal hairs thick and long, pointed and each with a tuberculate base. Head with one pair of frontal hairs, one pair of dorsal hairs between antennae, and two pairs of dorsal hairs between eyes. Length of cephalic hairs 0.093 mm, 36 widest diameter of antennal segment III. Eyes with three facets. Antennae four-segmented, 0.46 body length ( Figure 26). Length in proportion of segments I-IV: 36, 36, 100, 63+91, respectively; processus terminalis 1.436 base of the segment IV. Antennal hairs stout, long and pointed, segments I-IV each with 3, 2, 3, 2+0 hairs, respectively, apex of processus terminalis with three hairs; length of hairs on segment III 2.676 widest diameter of the segment. Rostrum reaching abdominal segment IV; ultimate rostral segment stout and short, wedge-shaped, 4.296 basal width, 1.676 second hind tarsal segment.
Thorax: dorsum of thorax pale. Dorsal hairs of thorax thick and long, pointed or ramose, each with a tuberculate base. Pronotum with four pairs of spinal and four pairs of marginal hairs; mesonotum and metanotum each with one pair of spinal, one pair of pleural, and one pair of marginal hairs. Legs pale, except claws brown. Tibiae with weakly transverse imbrications. Hind femur 1.186 antennal segment III; hind tibia 0.216 body length. Length of hairs on hind tibiae 1.336 mid-diameter of the segment. First tarsal chaetotaxy: 2, 2, 2.
Abdomen: pale. Dorsal hairs of abdomen thick and long, pointed or ramose, most dorsal hairs with tuberculate base. Abdominal tergites I-VI each with one pair of spinal, one pair of pleural, and one pair of marginal hairs; tergite VII with one pair of cone-shaped marginal tubercles, each with one long hair at apex, and one pair of spinal hairs ( Figure 28); tergite VIII with one pair of spinal tubercles, each with one long hair at apex. Length of marginal hairs on abdominal tergite I about 46 widest diameter of antennal segment III. Siphunculi short, cone-shaped ( Figure 27); 26 basal width, 66 distal width, 0.136 body length. Cauda semi-round, 0.56 basal width, with two hairs. Anal plate transversely elliptical, with four hairs.