Onthophagus semifex Krikken & Huijbregts, 2008

"I'm glad we're starting to get noticed for our work done. Don't worry folks and children. There will always be dung for us till the day we get widely recognized!"- Adult dung beetle
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Permission is granted by Krikken & Huijbregts for the use of image

Introduction


You may have heard and seen many flamboyant and magnificent animals in the zoo, but are they the only one we can care about?
Many of the species on Earth have yet to be described or documented, thus they are still unknown and not recognized for their ecological influences on nature and Man. Luckily for Onthophagus semifex, several aspects of its biology are described in the year 2008, though it is still relatively incomplete and insufficient as compared to many other renowned animals. But to be able to gain an official name, this little dung beetle is fortunate enough to enter the encyclopedia of life before its extinction.
Many of us probably would not bother what this little creature can do in nature. They:
  1. clear up the dung left by other big animals, and sometimes carrions
  2. help in secondary seed dispersal
  3. mediate nutrient cycling in the ecosystem

To evolve and take up these tedious work, they should be given much credit and recognition for their life commitment to do these great services for nature, and indirectly for Man. At the very least, i decide to set up this page to let the species be known for its contributions, or the minimum, its existence.



This song is dedicated to all dung beetles in the world, for their lifetime contributions and efforts.
FUN FACT
Dung beetles are sacred to the ancient Egyptians. They are deemed as their god of Sun, Ra, and the dung it rolled represents the sun.

Etymology


Onthophagus semifex
The species name semifex is a combined derivation from its related species, O. semiaureus (Lansberge, 1883) and O. aurifex (Harold, 1877). Both aurifex and aureus in Latin have related to metallic gold.
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Onthophagus species are boxed up in red. This picture is taken in the Raffles Museum of Biodiversity Research, National University of Singapore, Singapore. Picture by M.Y Neo.

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The red arrows indicate the cupreous appearance on the Onthophagus species. This picture is taken in the Raffles Musuem of Biodiveristy Research, National University of Singapore, Singapore. Picture is by M.Y. Neo

Feeding habits, foraging characteristics and reproduction

Note:
As O. semifex is not individually studied till date, many of its ecology habits are not well documented. However, their characteristics can be possibly inferred from the other Onthophagus relatives. Information in this section is subjected to change over time.

Diet and food choiceAccording to Hanski (1989), Onthophagus species, which were once living in tropical grasslands and mainly coprophagous, have become generalists to select for both dung and carrion for food as they moved to tropical forests. The observation of this shift in food specialization could be attributed to the optimal foraging theory. The abundance in a food source could hence predict a particular diet specialization to occur in these tropical dung beetles. Hanski (1989) has also pointed that in tropical forests, there is an absence of large herds of herbivorous animals, except the existence of small to medium animals, such as treeshrews (Tupaia glis), macaques (Macaca fascicularis) and squirrels (Sundasciurus tenuis) (Lee et al., 2009). As such, most dung beetles in tropical forests would be attracted to both dung and carrion, due to the general low food availability. This scenario would be well applicable to dung beetle species in Singapore tropical forests.
Human feces may be the best choice of dung, as human is omnivorous and has a wide range of diet habit.
Foraging behaviourO. semifex, similar to other Onthophagus tropical dung beetles, may locate their food resource by smell. They fly in a zig-zag manner, usually one meter or less above ground and land close to the source of the odour. They are also known to be tunnellers, which they bury the dung in preformed burrows. They transport their food fast owing to resource competition by other dung beetles, necrophagous beetles and flies (Hanski, 1989; Philips et al., 2004).
Reproduction behaviourFor the development of gonads and eggs in dung beetles, they feed for a long period of time. This is due to the low food availability in tropical forests, particularly in Singapore, which is a price the offspring must pay (Hanski, 1989). In most dung beetles, one female will lay one single egg in one dung ball, which will be sealed up to prevent attacks from predators. The larvae will feed on the dung ball and develop into pupae, and lastly the young adult. The young adult then emerges from the dung ball (Emlen & Nijhout, 1999).

Distribution


Till date, O. semifex is found to be distributed in South-east Asia. They are mainly discovered in mainland Northern Sumatra, Sipura from the Sumatran West Coast Islands, the Malay Peninsula and South Vietnam, as indicated in the red thumbtacks on the map. In Singapore, O. semifex have been found and documented to exist in Bukit Timan Nature Reserve (BTNR) (Lee et al., 2009). This is highly possible, as arboreal animals such as the macaques are commonly found in BTNR. For this reason, the possibility of O. semifex occurring in the Central Catchment Nature Reserve (CCNR) will be high as well.
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Map is adapted from Tarasov et al. (2010), and re-illustrated on Google Map.

Taxonavigation

This section provides taxonomic information on O. semifex for individuals who will be interested to starting research on it.

Kingdom: Animalia

Diagnosis


Till date, there are currently eight dung beetle representatives belonging to the O. aurifex species group, under the genus Onthophagus of Latreille, 1802. O. aurifex was made the ‘type’ of this group. Furthermore the group has been divided into two complexes- the O. aurifex complex and the O. sarawacus complex in a recent article published by Tarasov et al. (2010). In this , the authors classified four representatives in the O. aurifex complex, which are characterized by their shiny metallic upper-side body.
The main lead of this page, O. semifex Krikken & Huijbregts, 2008 can be differentiated from other species by the morphology of the male genitalia, also known as aedeagus. The male reproductive organ is also the most important feature in species recognition (Krikken & Huijbregts, 2008). Figure 1 shows the aedeagus of some species in the same complex, which are morphologically distinct to some extent. According to both authors, the distal paramerite of O. semifex is neither multi-angulated nor projecting, and it is not separated from the basolateral plate, as shown in Figure 1(a) (i).

However, same species in different locations can slightly differ in the shape of their aedeagus, as seen between the Vietnamese populations of O. semifex and those in the Sundaland (Tarasov et al., 2010). Nevertheless, their differences are too minor to classify them in different taxa.
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Figure 1. Permission is granted by Krikken & Huijbregts for the use of this image

Description


Figure 2 and 3 below respectively present the morphological anatomy of O. semifex, and a simplified labeling of the different body parts found in this dung beetle. A glossary table- Table 1, has been created to also provide definitions and their individual corresponding description. More detailed descriptions on the morphology of O. semifex are furthered discussed in the article written by Krikken & Huijbregts (2008) .
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Figure 2: Permission is granted for the use of picture by Krikken & Huijbregts

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Figure 3: Permission is granted for the use of picture by Krikken & Huijbregts
1. Head (Figure 2a) The head is observed to have no non-marginal protrusions. At the clypeal margin, it is anteriorly reflexed, with the presence of a short rounded tooth at the apex position. The head is also cupreous and punctuated. The eyes are small and elliptic. The approximated maximum width of the head is 3.3mm.
2. Pronotum (Figure 2b) The pronotum is convexly structured and entirely cupreous. Punctures and setae can also be observed on the pronotum. The number of punctures per 0.25 sq mm is approximately 25-30, with very fine diameters of 0.01mm. However, the size and abundance of the punctures can vary t different parts of the pronotum. The approximate median length and maximum width is 4.0mm and 5.8mm respectively.
3. Eltyron (Figure 2c) Elytron, also known as the fore-wing, is dark brown and matt. Yellow-brown setae, together with punctures, are present in abundance. The setae are of lengths three to five punctural diameters. Also, striations are lightly impressed, but can be distinctively observed on the elytron. These striations also carry punctures, whereby each of them is separated by 0.03-0.05mm. The estimated sutural length of the elytra when viewed dorsally is 4.5mm, and the maximum width of elytra combined is 6.1mm.
4. Protibia (Figure 2d) The protibia is described as robust, brown and shiny in colour and appearance. It carries four denticles, which are pointed and thin in structures. The denticles resemble tooth-like projections seen on a saw weapon. The protibia also carries an elongated pointed spur.
5. Metatibia (Figure 2e) The metatibia is dark-brown in colour and shiny. Its sides are covered with spines. Similar to the protibia, the metatibia contains a spur, which is also robust, sharp and long.
6. Aedeagal (Figure 2f (i) and 2f (ii)) The aedeagal, as previously mentioned, is the diagnostic body part used to distinguish the different species. In O. semifex, the distal paramerite is neither multi-angulate nor projecting.
Table 1: Glossary
Morphological terms
Description
Aedeagaus
Male reproductive organ
Clypeal margin
Lower margin of the clypeus (which is the median region of the head above the mouth)
Elytron
Fore-wing commonly found in Coleoptera. It is longitudinally oriented, and meeting the opposite elytron along a midline
Metatibia
Longest segment of the hind leg, which is located at the metathorax
Pronotum
Dorsal portion of the prothroax
Protibia
Usually the longest segment of the fore leg in beetles, which is located at the prothorax
Puncture
Small needle-like impressions
Setae
A Latin word for “bristle”, or hair-like projections

Type Information


The holotype of O. semifex is stored in the Regional Museum: National Museum of Natural History (RMNH), located in the Netherlands. The holotype is found and collected at above 810 meters sea level in the forests of North Sumatra, from human excrements (Krikken & Huijbregts, 2008). Other type specimens of O. semifex can be also located in the Raffles Museum of Biodiversity Research (RMBR), National University of Singapore, Singapore. Interested individuals are able to locate these specimens at these locations for research references.

Acknowledgements


A very big thanks to the following authors and individuals for their utmost contributions to this species page- Onthophagus semifex [in random order]: Jan Krikken (Institude of Natural Science, Kaluga State Pedagogical University, Russia); Johannes Huijbregts (Natioal Museum of Natural History Naturalis, the Netherlands); Sergey Tarasov (Department of Entomology, Natural History Museum of Denmark/University of Copenhagen, Zoological Museum); T. Keith Philips (Department of Biology, Western Kentucky University, Kentucky; Department of Zoology and Entomology, University of Pretoria, South Africa); Lua Hui Kheng (Curator of bird, insect, mammal and mollusc collection, RMBR, National University of Singapore, Singapore).

References


Emlen, D.J. & Nijhout, F.H. (1999). Hormal control of male horn length dimorphism in the dung beetle Onthophagus taurus (Coleoptera: Scarabaeidae). Journal of Insect Physiology. pp. 45: 45-53.
Hanski, I. (1989). Dung Beetles. Tropical Rain Forest Ecosystems. pp. 28: 489-511.
Krikken, J. & Huijbregts, J. (2008). Distinguishing the Sundaland species in the Onthophagus (Parascatonomus) aurifex group (Coleoptera: Scarabaeidae: Scarabaeinae). Tijdschrift voor Entomologie. pp. 151: 173-185.
Lee, J.S.H., Cheung, Y.K. & Qie, L. (2009). Possible extinctions of dung beetles (Coleoptera: Scarabaeidae) in Bukit Timah Nature Reserve, Singapore. The Raffles Bulletin of Zoology. pp. 57(2): 537-542.
Tarasov, S., Krikken, J. & Huijbregts, J. (2010). The Indochinese members of the Onthophagus (Parascatonomus) aurifex species group (Coleoptera: Scarabaeidae), with the description of a new species. Zootaxa. pp. 2490: 63-68.

Discussion Section


Your discussions, opinions and reviews for this site will be greatly appreciated. If you have any new information on Onthophagus semifex that you wish to be added in, do leave your reference material and your contact in the discussion box below. Your request will be attended as soon as possible.

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Introduction | Etymology | Feeding habits, foraging characteristics and reproduction | Distribution | Taxonavigation | Diagnosis | Description | Type Information | Acknowledgements | References | Discussion Section 1. Head (Figure 2a)The head is observed to have no non-marginal protrusions. At the clypeal margin, it is anteriorly reflexed, with the presence of a short rounded tooth at the apex position. The head is also cupreous and punctuated. The eyes are small and elliptic. The approximated maximum width of the head is 3.3mm.2. Pronotum (Figure 2b)The pronotum is convexly structured and entirely cupreous. Punctures and setae can also be observed on the pronotum. The number of punctures per 0.25 sq mm is approximately 25-30, with very fine diameters of 0.01mm. However, the size and abundance of the punctures can differ at different parts of the pronotum. The approximated median length and maximum width is 4.0mm and 5.8mm respectively.3. Elytron (Figure 2c)Elytron, also known as the fore-wing, is dark brown and matt. Yellow-brown setae, together with punctures, are present in abundance. The setae are of lengths three to five punctural diameters. Also, striations are lightly impressed, but can be distinctively observed on the elytron. These striations also carry punctures, whereby each of them is separated by 0.03-0.05mm. The estimated sutural length of the elytra when viewed dorsally is 4.5mm, and the maximum width of elytra combined is 6.1mm.4. Protibia (Figure 2d)The protibia is described as robust, brown and shiny in colour and appearance. It carries four denticles, which are pointed and thin in structures. The denticles resemble tooth-like projections seen on a saw weapon. The protibia also carries an elongated pointed spur.5. Metatibia (Figure 2e)The metatibia is dark-brown in colour and shiny. Its sides are covered with spines. Similar to the protibia, the metatibia contains a spur, which is also robust, sharp and long.6. Aedeagal (Figure 2f (i) and 2f (ii))The aedeagal, as previously mentioned, is the diagnostic body part used to distinguish the different species. In O. semifex, the distal paramerite is neither multi-angulate nor projecting