Reddyanus Vachon, 1972

Reddyanus Vachon, 1972 View in CoL

( Figure 4 View Figure 4 , Table 1)

COMMENTS. The genus Reddyanus Vachon, 1972 is distributed from East Asia (Tibet Autonomous Region, China), South Asia, Southeast Asia and Oceania, with most of which found in India (9 spp. records), Sri Lanka (6 spp. records), Malaysia (5 spp. records), Indonesia (4 spp. records) and Vietnam (4 spp. records). One species, R. deharvengi (Lourenço & Duhem, 2010) , is included in the IUCN Red List ( Tang, 2022b: 17). This genus was initially described as a subgenus of Isometrus Ehrenberg, 1828 , differentiated by the positions of trichobothria and pedipalp finger dentitions ( Vachon, 1972, 1982). Kovařík et al. (2016: 54, 56) elevated it to the genus level based on their disparities in tarsal setation and hemispermatophore structure. This taxonomic decision was subsequently supported by a molecular analysis in Štundlová et al. (2022). Additional characters often useful in many subordinate taxa of the two genera include the relative ratio of pedipalp chela (typically more robust in Reddyanus but slender with proportionally longer fingers in Isometrus , at least in males) and the shape of subaculear tubercle of telson (typically rhomboid in Reddyanus but always triangular in Isometrus ).

Apart from the 33 species listed in Kovařík & Šťáhlavský (2019: 3) and Kovařík et al. (2020: 3), three additional species are hereby added to the genus Reddyanus : R. aareyensis (Mirza & Sanap, 2010) , R. hainanensis (Lourenço et al., 2005) and R. lao (Lourenço & Leguin, 2012) . Reddyanus aareyensis , originally classified under the genus Lychas C. L. Koch, 1845 , was subsequently transferred to its current genus by the first author of its original description after a re-examination upon its leg tibia (lacking tibial spur) and trichobothrial pattern of pedipalp manus (Mirza, 2020: 323–324). On the contrary, the latter two species were excluded from this genus in Kovařík & Šťáhlavský (2019: 3). As summarized in Tang (2022b), R. hainanensis was once synonymized with R. petrzelkai (Kovařík, 2003) by Kovařík & Ojanguren (2013: 191), a decision subsequently retracted in Kovařík & Šťáhlavský (2019: 3). Current scrutiny of its original description and online photographs (MNHN-RS-RS1175) confirmed its unambiguous placement within Reddyanus , although a redescription of this species is warranted. Additionally, the morphometrics of R. hainanensis are distinctive in terms of its L/W ratio of metasomal segment V ( Table 2). Reddyanus lao underwent the same taxonomic changes as that of R. hainanensis (Kovařík & Šťáhlavský, 2019: 3) . While its morphometrics are quite similar to those of R. petrzelkai ( Table 2), the original authors did not provide any comparisons, albeit their disjunct geographical distribution.

Reddyanus petrzelkai was originally described from Tri An dam, Vietnam, with an additional paratype male from Chanthaburi, Thailand (Kovařík, 2003: 11). This paratype was then ignored in Kovařík & Ojanguren (2013) and other subsequent papers; its geographic location suggests it might be conspecific with, if not representing a new species, either R. neradi (Kovařík, 2013) from Namtok Phlio, or R. schwotti Kovařík & Šťáhlavský, 2019 from Sa Kaeo Province. Records of R. petrzelkai from Sen Monorom ( Cambodia) and Tao Island ( Thailand) (Kovařík & Ojanguren, 2013: 192) were subsequently revealed to be two new species in their original description, R. rolciki Kovařík & Šťáhlavský, 2019 and R. schwotti Kovařík & Šťáhlavský, 2019 . Reddyanus deharvengi is another species found in close proximity to these four species but distinguishes itself by having 10 carinae on metasoma II (vs. 8; Kovařík & Šťáhlavský, 2019: 43). Discarding this doubtful distinction (no verifiable illustration; Lourenço & Duhem, 2010: 635) renders R. schwotti highly resemblant of R. deharvengi , particularly when comparing the male paratypes of R. schwotti from Tao Island ( Thailand) and Bokor ( Cambodia) with the holotype male of R. deharvengi . However, it is beyond my scope to confirm if R. deharvengi was erroneously described and whether the two species (or part of the populations) may be conspecific. Reddyanus petrzelkai was eventually recognized as an endemic species in Vietnam (Kovařík & Šťáhlavský, 2019: 23). Nevertheless, its previous records from Champassak ( Laos) and Koh Kong ( Cambodia) (Kovařík & Ojanguren, 2013: 192) await reappraisal. Despite R. petrzelkai being once considered relatively widespread (Kovařík & Ojanguren, 2013: 191), with the subsequent discovery of new species from its previously recorded localities, it appears that R. lao , discovered far from the type locality of R. petrzelkai , may also be heterospecific with this species ( Fig. 4 View Figure 4 ). Hence, R. lao is also hereby included in this genus as a valid species.

Conversely, the validity of R. tibetanus is questionable, a species described upon a single adult male, 38 years following its collection by Kurt Lindberg. The authors distinguished their new species from the geographically proximate R. assamensis based on a mere three enigmatic characteristics: (1) pigmentation (paler and weakly maculate in R. tibetanus ); (2) metasomal carinae and terminal tubercles (“posterior spinoid granules”) of dorsal carinae (weaker in R. tibetanus ); (3) granulations of carapace and tergites (weaker in R. tibetanus ). Coloration of specimens is known to be prone to alteration if poorly preserved, with patterns often fading over time. While chronological effect may induce color reduction, the extent to which the color diminishes also hinges on the specific chemical reaction between the specimen and its surroundings (e.g., the composition of preserving fluid and the ambient light of the environment where the specimen jar is stored). The specimen itself also holds several variables: for instance, the time interval between its most recent ecdysis and fixation in fluids, where freshly moulted individuals are paler. The differences on metasomal segments are indiscernible from their illustrations (cf. Lourenço & Zhu, 2008: figs. 1, 14), and those in granulations should ideally be substantiated by UV photographs which were regrettably absent in the original description. In light of this, I could only extrapolate the credibility of those authors pertaining to their statements on qualitative characters from their other publications. The senior author of R. tibetanus had previously described a new Hottentotta species, H. caboverdensis Lourenço & Ythier, 2006 , based on four purported characters, with one of which being “…(iii) more strongly marked granulations on carapace and tergites than in H. hottentotta and H. nigrocarinatus…” (Lourenço & Ythier, 2006: 72). It is evident, after superimposition, that their figures 2–3 which served to illustrate the interspecific difference of carapacial granulation were reciprocal and based on the same template; i.e., the illustrations for the two species’ carapace were not delineated independently yet modified from one another. This approach, albeit censurable, does not necessarily argue against the authenticity of such difference. However, further inference from the photographs of the holotype of H. caboverdensis (MNHN-RS-RS8610) and their juxtaposed species (Kovařík, 2007: fig. 9) deemed the implied assertion that “ H. caboverdensis possesses a more granulated carapace than H. hottentotta ” as unjustifiable. Similarly, the two authors of R. tibetanus had also collaborated on a description of a new Olivierus species based on the same character ( Sun et al., 2010: 36, figs. 2–4), which has been refuted in a recent revision (Tang et al., 2024a: 8–9). On that account, I cannot confidently reckon the similar claim proposed for their new Reddyanus cogent. In addition to those untenable qualitative characters, a substantial overlap exists in the meristics of the two species ( Table 2; or table 1 in Lourenço & Zhu, 2008: 270). The sole potential quantitative difference seems to lie in the chela L/W ratio of the males, where R. tibetanus appears to possess a narrower chela. Nevertheless, these data were not derived from a sufficient sample size, rendering it susceptible to variation biases and potential anthropogenic errors introduced during the manual measurement. At first glance, it seems that R. tibetanus possesses proportionally shorter and more robust fingers (cf. Lourenço & Zhu, 2008: figs. 3, 16). However, recent observations on iNaturalist revealed an intraspecific variation of R. assamensis pertaining to this aspect, based on specimens from India and Bangladesh (cf. obs. IDs = 190419156, 187339396), with the Indian specimen apparently matching R. tibetanus . Finally, as an important diagnostic character for this genus, the telson morphology (including the shape of subaculear tubercle, curvature of aculeus, and ratio of vesicle) also displayed no observable distinction between the males of two species (cf. Lourenço & Zhu, 2008: figs. 7, 20). Given the non-opposing and non-discrete nature of the three diagnostic characters proposed for R. tibetanus , an inevitable conclusion is that it embodies a junior subjective synonym of R. assamensis . The holotype of R. tibetanus was unable to be examined in this study as it is lost.

Concerning all three species, R. assamensis , R. tibetanus and R. hainanensis , the authors asserted that there were seven subrows of denticles on their pedipalp movable fingers (Lourenço & Zhu, 2008: 266, 270; Lourenço et al., 2005: 58), a character also employed to distinguish R. lao from R. hainanensis (Lourenço & Leguin, 2012: 74) , where R. lao was described as having only six subrows (similarly, they claimed that R. vittatus ( Pocock, 1900) had seven subrows). This contradicts prior knowledge of this genus, in which all species were considered with six subrows. The finger dentition of other Reddyanus species clearly accords with the following pattern (cf. Kovařík & Šťáhlavský, 2019: fig. 29; Lowe & Fet, 2024: fig. 175): six subrows of denticles on the cutting edge of movable fingers (apical row excluded) with the first five subrows flanked proximally by an internal accessory denticle (IAD) and an external accessory denticle (EAD). The assertion of seven subrows can likely be attributed to an EAD flanking the 6 th subrow (the most proximal subrow) midway, inducing the illusion of a 7 th subrow separated from the 6 th subrow by this EAD. The subrows of denticles are commonly identified by the disjunctions between adjacent subrows, eventually rendering them appear either imbricated or nonimbricated depending on how much the posterior subrow extends to the anterior subrow. The subrows anterior to the most proximal subrow are often slightly oblique proximally. Similar instances of confusion in the genus Olivierus Farzanpay, 1987 have also been clarified in Tang et al. (2024a: 11–12, 14). In reality, the continuity of the linearity of the 6 th subrow is evident for both R. assamensis and R. tibetanus , even when based on their hand-drawn illustrations (Lourenço & Zhu, 2008: 266, fig. 13; 268, fig. 26). Although there is a small gap slightly larger than most interdental spacings within the most proximal subrow near the EAD, it did not cause the dislocation that leads to the imbricated configuration in typical subrows, where the posterior subrow lies internal to the anterior one. In fact , if this small gap was the basis for the authors’ claim of seven subrows, then another gap located more proximally in R. tibetanus (Lourenço & Zhu, 2008: fig. 26), with five denticles between the two gaps, should qualify this species as having eight subrows. Therefore, the presence of seven subrows of denticles does not serve as a defensible basis for distinguishing these taxa from others. However, the illustration for R. hainanensis did show a disjunction at this denticle, resulting in an inwardly slanted profile (Lourenço et al., 2005: 61, fig. 14). Nevertheless, hand-drawn illustrations can be subject to manipulation and may not be entirely reliable. Another plausible explanation is that the finger was accurately illustrated, and the disjunction was caused by the natural wear of the denticles.

More recently, in his revision of R. heimi ( Vachon, 1976) , Lourenço (2023) described a new species based on a 3 rd instar juvenile male from the type series of R. heimi deposited at Muséum national d’Histoire naturelle, Paris, France. He rejected the taxonomic decision by Kovařík et al. (2016) and retained Reddyanus as a subgenus of Isometrus , again without proposing any valid justifications (Lourenço, 2023: 32), but instead arbitrarily defining “artificial” and “valid” genera on his own accord. It is arguable that fragmenting one genus into several entities could compromise its taxonomic stability (Mahony et al., 2024). However, as much as any decision to pursue such atomization should be underpinned by a comprehensive, integrative framework supported by robust evidence, criticisms levied against such a course of action must be grounded in objective evaluations to ensure their defensibility. The original description of R. kanak conveniently included only a handful of artificial illustrations for the new species (Lourenço, 2023: figs. 8–14), rendering the accuracy of interspecific differentiations doubtful. In the five differential characters he proposed, characters 1 and 5 are indisputably invalid given the immaturity of the holotype. Character 4 is unobservable and can be heavily influenced by the condition of the preserved specimen (note that in Tang et al., 2023: fig. 91, even for the same sex of the same species, the prosoma profile may differ due to distortion). Validity of character 3 remains in question until a thorough investigation is conducted upon the intraspecific variation of trichobothrial positions of both species. The only apparently valid feature lies in character 2. However, the first two features are rather dubious, especially the development of carination which cannot be verified unless photographs of the authentic specimen are provided. Lourenço (2023: 34) stated that “… un aiguillon un peu plus long et moins recourbé (a slightly longer and less curved aculeus)…”, a character which may actually represent the common sexual dimorphism in this genus where the aculeus is typically shorter and more curved in males (op. cit.: figs. 15–16). The author did not indicate how he identified the sex of the immature specimen, given that the pectinal tooth count, an age-independent meristic often exhibiting sexual dimorphism, is not practical for such differentiation in Reddyanus , while all other sexually dimorphic characters (e.g., ratiometrics of metasoma and pedipalps) are only expressed in late instars and adults. Presumably, the relative size of the pectines was leveraged, although it is uncertain if its sexual difference is prominent or reliable at 3 rd instar. The mere strong discordance against the diagnostic characters of this genus involves the absence of a subaculear tubercle in his new species (op. cit.: fig. 14). Based on my current knowledge, this structure is omnipresent and age-independent across all previous species of Reddyanus . Given that no other materials are known for this species and there is not a single photo for the holotype, one cannot reject the likelihood of teratology or anomality (as also mentioned by the author: “… Vachon (1976) écarta l’exemplaire en question comme étant atypique …” [ Vachon (1976) discarded the specimen in question as atypical]). Similar telsonic anomaly has been observed in a male Lychas aff. buchari by Newton (2007). The malformed telson was featured by a narrowed vesicle and a thickened aculeus with a bifurcated tip, whose subaculear tubercle was diminished. The holotype R. kanak was also illustrated with a proportionally thickened aculeus at the basal section. Upon reviewing online photographs of normal immature Reddyanus species, it appears that the girth of aculeus is not, if at all, ontogenetically variable. In light of these considerations, I refrain from including R. kanak Lourenço, 2023 within this genus, while assuming its status as a nomen dubium.

Consequently, 35 species are recognized here for this genus. In comparison with the list of 33 species in Kovařík & Šťáhlavský (2019) and Kovařík et al. (2020): R. aareyensis , R. hainanensis and R. lao are added; R. tibetanus is removed and synonymized with R. assamensis ; R. kanak is considered a nomen dubium and not included in the count.