Hystrignathus nunashae, Oca & Sarmiento-Ruiz & Cardenas-Callirgos & Oceguera-Figueroa, 2022

Oca, Uriel Garduño-Montes De, Sarmiento-Ruiz, Thalia, Cardenas-Callirgos, Jorge Manuel & Oceguera-Figueroa, Alejandro, 2022, A new species of Hystrignathus (Nematoda: Thelastomatoidea: Hystrignathidae) associated with the Bess Beetle Passalus Interruptus Linnaeus (Coleoptera: Passalidae) from The Peruvian Amazonia, Zootaxa 5159 (3), pp. 354-366 : 357-361

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Hystrignathus nunashae

n. sp.

Hystrignathus nunashae n. sp. Garduño-Montes de Oca 2022

Fig. 1 A–E View FIGURE 1 , Fig. 2 A–D View FIGURE 2

Measurements are listed in Table 1 View TABLE 1 .

Type material. Holotype: Female MUSM-HELM 4750 . Paratypes (recovered from two hosts): Female MUSMHELM 4751 (3 specimens), Female CNHE 8600 (4 specimens), same data as the holotype. Preserved in 80% ethanol. Hand collected host. Cols. U. Garduño-Montes de Oca, T. Sarmiento-Ruiz, A. Oceguera-Figueroa .

Type locality. Peru, Huánuco, Tingo María ( UNAS) 9°19’10.1”S, 75°59’32.8”W, 14-VI-2018 GoogleMaps .

Etymology: The new species is named after Nunash, the mythical princess of the jungle, who according to popular legend became the mountain known as the “sleeping beauty”, a natural monument of Tingo María, Peru.

Type host: Passalus interruptus Linnaeus 1758 ( Coleoptera : Passalidae ).

Site of infection: Hindgut.

Measurements. Table 2 View TABLE 2 .

Description (based on 8 female specimens). Fusiform nematodes ( Fig. 1A View FIGURE 1 ), rounded cephalic extremity formed by 2 annules, the posterior one notoriously dilated, wider than anterior annule ( Fig. 1B View FIGURE 1 ). Triangular oral opening surrounded by 4 pairs of rounded papillae, amphids lateral. Posterior annule with rounded margins ( Figs. 1B View FIGURE 1 , 2C View FIGURE 2 ). Cervical cuticle with about 70 transverse rows of retrorse spines aligned longitudinally from the posterior oral annule (before the posterior end of stoma) to near the base of procorpus ( Figs. 1D View FIGURE 1 , 2C View FIGURE 2 ), the length of the spines is shorter at the extremes of their distribution, presenting barely distinguishable spines at the level of the base of the procorpus. Cuticle finely annulated from posterior cervical annule to anal region ( Figs. 2B–D View FIGURE 2 ). Lateral alae present, beginning at procorpus level and ending at anal region, near the anus ( Figs. 1A, D View FIGURE 1 , 2B–C View FIGURE 2 ). Stoma narrow and cylindrical, surrounded by an oesophageal collar ( Fig. 1D View FIGURE 1 ). Oesophagus with clavate procorpus, its diameter increases towards its posterior end, evident isthmus and a sub-spherical bulb with valves ( Fig. 1A, D View FIGURE 1 ). Nerve ring located approximately at the middle region of the corpus ( Fig. 1A, D View FIGURE 1 ). Excretory pore post-bulbar ( Fig. 1A View FIGURE 1 ). Vulva in the posterior half of body, located about the beginning of last third of body, vagina anteriorly directed ( Fig. 1A View FIGURE 1 ). Didelphic-amphidelphic genital tract ( Fig. 1A View FIGURE 1 ). Eggs ovoid, its shell ornamented with longitudinal ridges ( Fig. 1E View FIGURE 1 ). Tail short, subulate ( Figs. 1A View FIGURE 1 , 2D View FIGURE 2 ).

Remarks. Hystrignathus nunashae n. sp. is the 22nd species assigned to Hystrignathus . Species of the genus are characterized by the presence of an anterior end formed by two annules, procorpus clavate, cervical cuticular ornamentation formed by opposite rows of spines, as well as by having a didelphic-amphidelphic genital tract. The morphological traits of the new species described here are consistent with the description of the genus Hystrignathus .

Within the genus Hystrignathus , three characters are valuable for species identification and description: (1) the starting point of cervical spines with respect to the posterior end of stoma (i.e. union of the stoma and corpus) or the end of the posterior cephalic ring, (2) the shape of the posterior cephalic ring, and (3) the presence of ornamented eggs. Hystrignathus nunashae n. sp. have cervical spines beginning just after the end of the posterior cephalic ring (before the posterior end of stoma), this posterior cephalic ring is dilated and longer than the anterior one, and it shows longitudinal ornamentations on the eggshell.

Only two species of Hystrignathus display cervical spines beginning posterior to the stoma: H. cobbi Travassos & Kloss 1957 , and H. dearmasi Morffe & García 2010 (Morffe & García 2010); the remaining 20 species, including H. nunashae n. sp. have cervical spines beginning just after the end of the first cephalic annule, these species include: H. egalis Waerebeke & Remillet 1982 , H. ferox Hunt 1982 , H. heliae Travassos & Kloss 1957 , H. inegalis Van Waerebeke & Remillet 1982 , H. inflatus Travassos & Kloss 1957 , H. insularis Van Waerebeke 1973 , H. meridensis Guerrero 1980, H. metropolitanus Cordeiro 1981 , H. papillophorus Cordeiro 1981 , H. paulistanus Cordeiro 1981 , H. pearsoni Travassos & Kloss 1958 , H. popiliophagus Guerrero 1980, H. rescens Travassos & Kloss 1958 , H. rigidus Leidy 1850 , H. rosario García, Ventosa & Morffe 2009 , H. rugosus Travassos & Kloss 1958 , H. spinosus Travassos & Kloss 1957 , H. splendidus Morffe & García 2010 and H. tarda Artigas 1928 .

In addition to the beginning of the cervical spines, H. cobbi and H. dearmasi have a short and not dilated posterior cephalic ring, which differs from the long and dilated cephalic ring found in H. nunashae n. sp. The shape of posterior cephalic ring in H. nunashae n. sp. is shared only with three congeneric species: H. splendidus , H. tarda and H. inflatus . These three species also share the beginning point of cervical spines with H. nunashae n. sp., but they differ in the characteristics of the eggshell: H. tarda and H. inflatus have a smooth eggshell contrasting with the ornamentation of the eggshell of H. nunashae n. sp. Ornamented eggshells, like H. nunashae n. sp. are also shared by H. dearmasi , H. egalis , H. ferox , H. inegalis , H. metropolitanus , H. papillophorus , H. rescens , H. rosario , H. rugosus and H. splendidus , however, with the exception of H. splendidus , these species can be distinguished by having a short and undilated cephalic ring.

Hystrignathus nunashae n. sp. morphologically resembles H. splendidus since both species share a posterior cephalic annule notoriously dilated and longer than the anterior one, as well as anterior cuticular spines beginning after the posterior cephalic annule, and ornamented eggs with a ridged shell (Morffe & García 2010). However, H. nunashae n. sp. differs from H. splendidus by the extension of the lateral alae along body, it finish at level of vulva in H. spendidus while it extends to the anal region in H. nunashae n. sp.; also, the new species can be differentiated by the tail length, which is proportionally longer in H. nunashae n. sp. than in H. splendidus (c = 3.558 –4.538 vs. 5.71–6.41 respectively). Other meristic characters that are contrastingly different between both species include the length of the eggs, longer in H. nunashae n. sp. (0.113 –0.119 vs. 0.098 –0.108) and the proportional position of the vulva (V% = 44.444 –52.610 vs. 53.93–54.00). Thus, H. nunashae n. sp. has a relatively longer body and a vulva located closer to anterior end, compared to H. splendidus (Morffe & García 2010) .


Tavera, Department of Geology and Geophysics

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