Growth of alien Barbatula oreas Biogeography 19. 47–54. Sep. 20, 2017 Biogeographical diffusion of Aporia hippia (Lepidoptera: Pieridae) obtained from morphological comparison Kazumi Kanoh* The Research Institute of Evolutionary Biology 2-4-8 Kamiyoga, Setagaya-ku, Tokyo 158-0098, Japan Abstract. To gain insight into the distribution diffusion of the butterfly Aporia hippia (Bremer, 1861), geographical variations in the wing markings and in the morphology of the male genitalia of this species was compared. On the basis of the morphological comparison, it was speculated that A. hippia first spread to the east and west, extending from central China to Japan. Moreover, the population in China seems to have ex- panded northeastward (Khabarovsk region, Russia) and northward (Transbaikal region, Russia). In both distri- bution diffusions to Russia, wing markings were considered to have become simplified or to have faded out in parallel. Key words: Aporia hippia, Distributin diffusion Introduction the markings ultimately disappearing altogether or becoming so faint that the wings are almost white. In Japan, Aporia hippia (Bremer, 1861) is dis- Kanoh et al. (2017) also thought that A. hippia prob- tributed in the subalpine zone of the central moun- ably speciated because of distribution diffusion from tainous region. Outside Japan, it is distributed in A. lhamo (Oberthür, 1893), inhabiting the Hengduan the China continent, the northern part of the Korean Mountains of China, via A. procris (Leech, 1890) Peninsula, northern Mongolia, and the Russian Far and A. bieti (Oberthür, 1894). It was assumed that East. Della Bruna et al. (2013) classified this species it then passed over the East China Sea over the land into six subspecies. bridge during the glacial period and expanded its Kanoh et al. (2017) considered the geographical distribution to Japan. variations in the wing markings in various species of In the present study, the distribution of each sub- Aporia and speculated that evidence of distribution species of A. hippia, the characteristics of the wing diffusion (radiation), involving expansion of the geo- markings, and the morphology of the male genitalia graphical distribution while undergoing speciation, were further examined to estimate the distribution still exists in a continuous geographical cline. The diffusion. cline occurred as the distribution diffusion continued beyond species: the dark upper side of the forewings Materials and Methods and markings on the deep-yellow underside of the hindwings became simplified or faded out, with A distribution diagram was prepared on the basis ——————————————————————— of specimens’ labels, using specimens owned by the *Corresponding author: [email protected] Research Institute of Evolutionary Biology (RIEB) − 47 − Biogeographical diffusion of Aporia hippia (Lepidoptera: Pieridae) obtained from morphological comparison Kazumi Kanoh and the author and the works of Tshikolovets et al. in the wing markings and colors were the width of (2002, 2009). To observe the male genitalia, the tail the black lines on the wing veins, the width of the part of the specimen was excised, soaked, and treat- discocellular black spots on the upper side of the ed in an aqueous solution of 10% potassium hydrox- forewings, and the yellow color on the underside of ide at ambient temperature for two days, washed in the hindwings. Comparing these characteristics, A. water, and observed under a binocular stereoscopic hippia thibetana (Fig. 1-1 and 1-2), distributed in the microscope. The uncus was observed from the apex, western part of China, had clear black lines on the and an image in the transverse plane was drawn by veins of the upper side of the wings and thick black focusing the microscope on the area considered to lines on the veins of the underside of the hindwings. reflect the most distinctive part of the middle area. In addition, the underside of the hindwings was deep Speciation due to distribution diffusion was predict- yellow compared with those of the subspecies found ed according to the distribution patterns, and wing in other areas. markings and the continuous morphology in the A. h. thibetana shared some common characteris- male genitalia were observed and compared. tics with A. h. ssp. of Taishan, Shandong province in China, and A. h. japonica of the central mountainous Results region of Japan: thick black lines on the veins of the underside of the hindwings and wide, discocellular The geographical variations in the wing markings black spots on the upper side of the forewings. The of A. hippia are shown in Figs. 1 and 2, and a dia- characteristics of wing markings and the individual gram of the male genitalia is shown in Fig. 3. Also, sizes of these two subspecies were similar in both wing markings of each subspecies are given in Table sexes, except A. h. ssp. of Taishan, where they were 1 and the male genitalia in Table 2. somewhat compact (Fig. 1-3 and 1-4). The characteristics of geographical variations Comparing the male genitalia of both subspecies, Table 1. Characteristics of wing markings of Aporia hippia in different locality. Discocellular black Yellow color on the Black lines on the spots on the upper underside of wing veins Subspecies name locality side of forewings hindwings Thick Thin Thick Thin Deep Light Aporia hippia thibetana Tewo, Gansu, China ○ ○ ○ A. h. thibetana Shihuichang, Helan, Ningxia, (taupingi) China ○ ○ ○ A. h. ssp. Taishan, Shandong, China ○ ○ ○ A. h. japonica Yastugatake, Nagano, Japan ○ ○ ○ A. h. crataegioides Wataishan, Shaxi Sheng, China ○ ○ ○ A. h. occidentalis Terelj, Mongolia ○ ○ ○ A. h. hippia Chonmashan, North Pyongan, North Korea ○ ○ ○ Solnechny dist., Khabarovsk, A. h. hippia Russia ○ ○ ○ ※ Allows shows differentiation routes. − 48 − Biogeographical diffusion of Aporia hippia (Lepidoptera: Pieridae) obtained from morphological comparison Kazumi Kanoh Table 2. Characteristics of male genitalia of Aporia hippia in different locality. Ridge in the continuous Overhang on the side Curvature of the front Back of tegumen part of saccus and ring of tegumen part of tegumen Subspecies name locality Saddle Flat Devel- Undevel- type type Unclear Clear oped oped Strong Weak Tewo, Gansu, Aporia hippia thibetana China ○ ○ ○ ○ Shihuichang, A. h. thibetana (taupingi) Helan, Ningxia, China ○ ○ ○ ○ Taishan, Shan- A. h. ssp. dong, China ○ ○ ○ ○ Yastugatake, A. h. japonica Nagano, Japan ○ ○ ○ ○ Wataishan, A. h. crataegioides Shaxi Sheng, China ○ ○ ○ ○ Terelj, A. h. occidentalis Mongolia ○ ○ ○ ○ Chonmashan, A. h. hippia North Pyongan, North Korea ○ ○ ○ ○ Solnechny dist., A. h. hippia Khabarovsk, Russia ○ ○ ○ ○ ※ Allows shows differentiation routes. the back side of the tegumen was flat type (Fig. 3-C1 (Fig. 3-E and 3-F). In addition, A. h. hippia had an and D1), the others were saddle type, and there was undeveloped overhang on the side of the tegumen a clear ridge in the continuous part of the saccus and (Fig.3-G3 and 3-H3), and the curvature of the front the ring (Fig. 3-C2 and D2). These common features part of the tegumen was weak (Fig.3-G4 and 3-H4). were not found in other subspecies (Table 2). Therefore, the ring observed from the side was linear In contrast, A. h. hippia, distributed in the north- (Fig.3-G5 and 3-H5). Thus, A. h. crataegioides and ern part of the Korean Peninsula, northeastern China, A. h. occidentalis were similar, but there was a clear the Amur region, and the Primorsky and Khabarovsk difference with A. h. hippia. regions of Russia, had a bright lemon-yellow color on the underside of the hindwings, thin black lines Discussion on the wing veins, and thin discocellular spots on the upper side of the forewings (Fig. 2-1 and 2-2). A. h. Kanoh et al. (2017) estimated that A. hippia spe- crataegioides, found around Beijing, China, and A. ciated from A. bieti in the area around Tewo, Gansu h. occidentalis, inhabiting the Mongolian and Trans- province, China, where the two distributions are the baikal regions of Russia, had a bright lemon-yellow closest. A. h. thibetana in Tewo (Fig. 1-1) showed color on the underside of the hindwings, thin black that the black lines on the wing veins were the thick- lines on the wing veins, and thin discocellular spots est on both sides of the wings in A. h. thibetana and on the upper side of the forewings (Fig. 2-3 and that the underside of the hindwings was particularly 2-4). Comparing the male genitalia, the length of yellow. These features were similar to those of A. the tegumen differed, but other features were similar bieti and are considered the oldest features of A. − 49 − Biogeographical diffusion of Aporia hippia (Lepidoptera: Pieridae) obtained from morphological comparison Kazumi Kanoh Fig. 1. Geographic variation in Aporia hippia, part 1 a: Male upper side. b: Male underside. c: Female upper side. d: Female underside. S: Discocellular black spot. Y: Yellow color on the underside of hindwing. L: black line on the wing vein. 1: Aporia hippia thibetana, Tewo, Gansu, China (a-d). FWL = 28.3 mm (a), 25.0 mm (c). 2: A. h. thibetana (taupingi), Shihuichang, Helan, Ningxia, China (a-d). FWL = 31.0 mm (a), 32.0 mm (c). 3: A. h. ssp. Taishan, Shandong, China (a-d). FWL = 31.8 mm (a), 37.0 mm (c). 4: A. h. japonica, Yastugatake, Nagano, Japan (a-d). FWL = 33.7 mm (a), 37.7 mm (c). − 50 − Biogeographical diffusion of Aporia hippia (Lepidoptera: Pieridae) obtained from morphological comparison Kazumi Kanoh Fig. 2. Geographic variation in Aporia hippia, part 2 a: Male upper side. b: Male underside. c: Female upper side. d: Female underside 1: Aporia hippia hippia. Solnechny dist., Khabarovsk, Russia (a-d). FWL = 33.5mm (a), 32.8 mm (c). 2: A. h. hippia. Chonmashan, North Pyongan, North Korea (a-d). FWL = 33.7 mm (a), 33.8 mm (c). 3: A. h. crataegioides. Wataishan, Shaxi Sheng, China (a-d). FWL = 34.0 mm (a), 39.7 mm (c).